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de Siqueira GMV, Silva-Rocha R, Guazzaroni ME. Turning the Screw: Engineering Extreme pH Resistance in Escherichia coli through Combinatorial Synthetic Operons. ACS Synth Biol 2020; 9:1254-1262. [PMID: 32438805 DOI: 10.1021/acssynbio.0c00089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Adoption of microorganisms as platforms for sustainable biobased production requires host cells to be able to withstand harsh conditions, usually very distant from those in which these organisms are naturally adapted to thrive. However, novel survival mechanisms unearthed by the study of microbiomes from extreme habitats may be exploited to enhance microbial robustness under the strict conditions needed for different industrial appplications. In this work, synthetic biology approaches were used to engineer enhanced acidic resistance in Escherichia coli through the characterization of a collection of unique operons composed of combinatorial assemblies of three novel genes from an extreme environment and three synthetic ribosome binding sites. The results here presented illustrate the efficacy of combining different metagenomic genes for resistance in synthetic operons, as expression of these gene clusters increased hundred-fold the survival percentage of cells exposed to an acidic shock in minimal media at pH 1.9 under aerobic conditions.
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Affiliation(s)
- Guilherme M. V. de Siqueira
- Departamento de Bioquı́mica, Faculdade de Medicina de Ribeirão Preto (FMRP-USP), Ribeirão Preto, SP 14049-900, Brasil
| | - Rafael Silva-Rocha
- Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto (FMRP-USP), Ribeirão Preto, SP 14049-900, Brasil
| | - María-Eugenia Guazzaroni
- Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto (FFCLRP-USP), Ribeirão Preto, SP 14040-901, Brasil
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Brameyer S, Hoyer E, Bibinger S, Burdack K, Lassak J, Jung K. Molecular design of a signaling system influences noise in protein abundance under acid stress in different γ-Proteobacteria. J Bacteriol 2020; 202:JB.00121-20. [PMID: 32482722 PMCID: PMC8404709 DOI: 10.1128/jb.00121-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/22/2020] [Indexed: 12/16/2022] Open
Abstract
Bacteria have evolved different signaling systems to sense and adapt to acid stress. One of these systems, the CadABC-system, responds to a combination of low pH and lysine availability. In Escherichia coli, the two signals are sensed by the pH sensor and transcription activator CadC and the co-sensor LysP, a lysine-specific transporter. Activated CadC promotes the transcription of the cadBA operon, which codes for the lysine decarboxylase CadA and the lysine/cadaverine antiporter CadB. The copy number of CadC is controlled translationally. Using a bioinformatics approach, we identified the presence of CadC with ribosomal stalling motifs together with LysP in species of the Enterobacteriaceae family. In contrast, we identified CadC without stalling motifs in species of the Vibrionaceae family, but the LysP co-sensor was not identified. Therefore, we compared the output of the Cad system in single cells of the distantly related organisms E. coli and V. campbellii using fluorescently-tagged CadB as the reporter. We observed a heterogeneous output in E. coli, and all the V. campbellii cells produced CadB. The copy number of the pH sensor CadC in E. coli was extremely low (≤4 molecules per cell), but it was 10-fold higher in V. campbellii An increase in the CadC copy number in E. coli correlated with a decrease in heterogeneous behavior. This study demonstrated how small changes in the design of a signaling system allow a homogeneous output and, thus, adaptation of Vibrio species that rely on the CadABC-system as the only acid resistance system.Importance Acid resistance is an important property of bacteria, such as Escherichia coli, to survive acidic environments like the human gastrointestinal tract. E. coli possess both passive and inducible acid resistance systems to counteract acidic environments. Thus, E. coli evolved sophisticated signaling systems to sense and appropriately respond to environmental acidic stress by regulating the activity of its three inducible acid resistance systems. One of these systems is the Cad system that is only induced under moderate acidic stress in a lysine-rich environment by the pH-responsive transcriptional regulator CadC. The significance of our research is in identifying the molecular design of the Cad systems in different Proteobacteria and their target expression noise at single cell level during acid stress conditions.
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Affiliation(s)
- Sophie Brameyer
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Elisabeth Hoyer
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Sebastian Bibinger
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Korinna Burdack
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Jürgen Lassak
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Kirsten Jung
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
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Abstract
Staphylococcus aureus colonizes or causes infection in a multitude of niches within a mammalian host. Many of these niches are acidic, yet specific pH resistance mechanisms that facilitate survival have not been thoroughly investigated. This review discusses recent studies documenting known acid resistance mechanisms in S. aureus and other staphylococcal species. However, studies that clearly define the regulation of the acid resistance regulon and potential interactions with weak organic acids in specific niches of the host including the skin and gut are yet to be defined.
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Affiliation(s)
- Chunyi Zhou
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Paul D Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States.
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Chen XK, Li XY, Ha YF, Lin JQ, Liu XM, Pang X, Lin JQ, Chen LX. Ferric Uptake Regulator Provides a New Strategy for Acidophile Adaptation to Acidic Ecosystems. Appl Environ Microbiol 2020; 86:e00268-20. [PMID: 32245756 PMCID: PMC7237784 DOI: 10.1128/aem.00268-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/16/2020] [Indexed: 12/25/2022] Open
Abstract
Acidophiles play a dominant role in driving elemental cycling in natural acid mine drainage (AMD) habitats and exhibit important application value in bioleaching and bioremediation. Acidity is an inevitable environmental stress and a key factor that affects the survival of acidophiles in their acidified natural habitats; however, the regulatory strategies applied by acidophilic bacteria to withstand low pH are unclear. We identified the significance of the ferric uptake regulator (Fur) in acidophiles adapting to acidic environments and discovered that Fur is ubiquitous as well as highly conserved in acidophilic bacteria. Mutagenesis of the fur gene of Acidithiobacillus caldus, a prototypical acidophilic sulfur-oxidizing bacterium found in AMD, revealed that Fur is required for the acid resistance of this acidophilic bacterium. Phenotypic characterization, transcriptome sequencing (RNA-seq), mutagenesis, and biochemical assays indicated that the Acidithiobacillus caldus ferric uptake regulator (AcFur) is involved in extreme acid resistance by regulating the expression of several key genes of certain cellular activities, such as iron transport, biofilm formation, sulfur metabolism, chemotaxis, and flagellar biosynthesis. Finally, a Fur-dependent acid resistance regulatory strategy in A. caldus was proposed to illustrate the ecological behavior of acidophilic bacteria under low pH. This study provides new insights into the adaptation strategies of acidophiles to AMD ecosystems and will promote the design and development of engineered biological systems for the environmental adaptation of acidophiles.IMPORTANCE This study advances our understanding of the acid tolerance mechanism of A. caldus, identifies the key fur gene responsible for acid resistance, and elucidates the correlation between fur and acid resistance, thus contributing to an understanding of the ecological behavior of acidophilic bacteria. These findings provide new insights into the acid resistance process in Acidithiobacillus species, thereby promoting the study of the environmental adaptation of acidophilic bacteria and the design of engineered biological systems.
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Affiliation(s)
- Xian-Ke Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Xiao-Yan Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Yi-Fan Ha
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Jian-Qiang Lin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Xiang-Mei Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Xin Pang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Jian-Qun Lin
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Lin-Xu Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
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Lackraj T, Birstonas S, Kacori M, Barnett Foster D. Dps Protects Enterohemorrhagic Escherichia coli against Acid-Induced Antimicrobial Peptide Killing. J Bacteriol 2020; 202:e00114-20. [PMID: 32229529 DOI: 10.1128/JB.00114-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/23/2020] [Indexed: 11/20/2022] Open
Abstract
Dps, a DNA-binding protein from starved cells in Escherichia coli, is part of the bacterial defense system that protects DNA against various cellular stresses. Our lab previously demonstrated that a novel antimicrobial peptide, WRWYCR, enhances acid-induced killing of enterohemorrhagic Escherichia coli (EHEC) and ameliorates infection in a Citrobacter rodentium mouse model of EHEC infection. WRWYCR has previously been shown to compromise DNA damage repair and to increase chelatable iron within the cell. These findings, combined with the effects of peptide and acid stress on DNA damage, suggest a key defense role for Dps in peptide-induced killing of EHEC. The goal of this study is to evaluate the role of Dps in peptide-induced killing of EHEC through survival assays and flow cytometric analyses of DNA damage and hydroxyl radical formation. Our results demonstrate that disruption of the dps gene in stationary-phase EHEC O157:H7 cells, but not in exponential-phase cells, enhances acid-, peptide-, and peptide-acid-induced killing relative to that of wild-type (WT) EHEC. Using flow cytometric analysis, we have also demonstrated increased levels of hydroxyl radicals in peptide-treated wild-type EHEC relative to those in the untreated control. Disruption of the dps gene further increases this. These findings indicate that peptide treatment of EHEC enhances the formation of hydroxyl radicals, likely through the Fenton reaction, thereby contributing to the killing action of the peptide, and that dps protects against peptide killing of EHEC. This study provides important insights into peptide WRWYCR-mediated killing of EHEC, which could be exploited in the development of more effective antimicrobials.IMPORTANCE The research presented in this paper explores the role of the DNA-binding protein Dps as a key defense mechanism of enterohemorrhagic Escherichia coli (EHEC) strains in protecting against killing by the novel antimicrobial peptide WRWYCR. Our results demonstrate that Dps protects against peptide-induced killing of EHEC through direct protection against acid stress and hydroxyl radical formation, both of which are mechanisms targeted by the antimicrobial peptide. This study provides important insights into peptide WRWYCR-mediated killing of EHEC, which could be exploited in the development of more effective antimicrobials through specific targeting of Dps in order to allow a more potent response to the antimicrobial WRWYCR.
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Xu L, Zhang D, Ronson TK, Nitschke JR. Improved Acid Resistance of a Metal-Organic Cage Enables Cargo Release and Exchange between Hosts. Angew Chem Int Ed Engl 2020; 59:7435-7438. [PMID: 32073709 PMCID: PMC7217015 DOI: 10.1002/anie.202001059] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Indexed: 01/06/2023]
Abstract
The use of di(2-pyridyl)ketone in subcomponent self-assembly is introduced. When combined with a flexible triamine and zinc bis(trifluoromethanesulfonyl)imide, this ketone formed a new Zn4 L4 tetrahedron 1 bearing twelve uncoordinated pyridyl units around its metal-ion vertices. The acid stability of 1 was found to be greater than that of the analogous tetrahedron 2 built from 2-formylpyridine. Intriguingly, the peripheral presence of additional pyridine rings in 1 resulted in distinct guest binding behavior from that of 2, affecting guest scope as well as binding affinities. The different stabilities and guest affinities of capsules 1 and 2 enabled the design of systems whereby different cargoes could be moved between cages using acid and base as chemical stimuli.
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Affiliation(s)
- Lin Xu
- Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
- Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular EngineeringEast China Normal University3663 N. Zhongshan RoadShanghai200062P. R. China
| | - Dawei Zhang
- Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Tanya K. Ronson
- Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
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Wu H, Xue E, Zhi N, Song Q, Tian K, Caiyin Q, Yuan L, Qiao J. d-Methionine and d-Phenylalanine Improve Lactococcus lactis F44 Acid Resistance and Nisin Yield by Governing Cell Wall Remodeling. Appl Environ Microbiol 2020; 86:e02981-19. [PMID: 32111594 DOI: 10.1128/AEM.02981-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 02/22/2020] [Indexed: 12/30/2022] Open
Abstract
Lactococcus lactis encounters various environmental challenges, especially acid stress, during its growth. The cell wall can maintain the integrity and shape of the cell under environmental stress, and d-amino acids play an important role in cell wall synthesis. Here, by analyzing the effects of 19 different d-amino acids on the physiology of L. lactis F44, we found that exogenously supplied d-methionine and d-phenylalanine increased the nisin yield by 93.22% and 101.29%, respectively, as well as significantly increasing the acid resistance of L. lactis F44. The composition of the cell wall in L. lactis F44 with exogenously supplied d-Met or d-Phe was further investigated via a vancomycin fluorescence experiment and a liquid chromatography-mass spectrometry assay, which demonstrated that d-Met could be incorporated into the fifth position of peptidoglycan (PG) muropeptides and d-Phe could be added to the fourth and fifth positions. Moreover, overexpression of the PG synthesis gene murF further enhanced the levels of d-Met and d-Phe involved in PG and increased the survival rate under acid stress and the nisin yield of the strain. This study reveals that the exogenous supply of d-Met or d-Phe can change the composition of the cell wall and influence acid tolerance as well as nisin yield in L. lactis IMPORTANCE As d-amino acids play an important role in cell wall synthesis, we analyzed the effects of 19 different d-amino acids on L. lactis F44, demonstrating that d-Met and d-Phe can participate in peptidoglycan (PG) synthesis and improve the acid resistance and nisin yield of this strain. murF overexpression further increased the levels of d-Met and d-Phe incorporated into PG and contributed to the acid resistance of the strain. These findings suggest that d-Met and d-Phe can be incorporated into PG to improve the acid resistance and nisin yield of L. lactis, and this study provides new ideas for the enhancement of nisin production.
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Vergara E, Neira G, González C, Cortez D, Dopson M, Holmes DS. Evolution of Predicted Acid Resistance Mechanisms in the Extremely Acidophilic Leptospirillum Genus. Genes (Basel) 2020; 11:E389. [PMID: 32260256 DOI: 10.3390/genes11040389] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/02/2020] [Accepted: 03/04/2020] [Indexed: 02/01/2023] Open
Abstract
Organisms that thrive in extremely acidic environments (≤pH 3.5) are of widespread importance in industrial applications, environmental issues, and evolutionary studies. Leptospirillum spp. constitute the only extremely acidophilic microbes in the phylogenetically deep-rooted bacterial phylum Nitrospirae. Leptospirilli are Gram-negative, obligatory chemolithoautotrophic, aerobic, ferrous iron oxidizers. This paper predicts genes that Leptospirilli use to survive at low pH and infers their evolutionary trajectory. Phylogenetic and other bioinformatic approaches suggest that these genes can be classified into (i) "first line of defense", involved in the prevention of the entry of protons into the cell, and (ii) neutralization or expulsion of protons that enter the cell. The first line of defense includes potassium transporters, predicted to form an inside positive membrane potential, spermidines, hopanoids, and Slps (starvation-inducible outer membrane proteins). The "second line of defense" includes proton pumps and enzymes that consume protons. Maximum parsimony, clustering methods, and gene alignments are used to infer the evolutionary trajectory that potentially enabled the ancestral Leptospirillum to transition from a postulated circum-neutral pH environment to an extremely acidic one. The hypothesized trajectory includes gene gains/loss events driven extensively by horizontal gene transfer, gene duplications, gene mutations, and genomic rearrangements.
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Yang M, Peng L, Chen A, Zeng Q, Shao J, Luo S, Gu J. Enhanced adsorption of Cd(II) using a composite of poly(acrylamide-co-sodium acrylate) incorporated LDH@MoS 24. Environ Technol 2020; 41:357-365. [PMID: 29985102 DOI: 10.1080/09593330.2018.1498922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 07/05/2018] [Indexed: 06/08/2023]
Abstract
The Mg/Al layered double hydroxide (Mg/Al-LDH) intercalated with the [Formula: see text] (MoS4-LDH) impregnated into poly(acrylamide-co-sodium acrylate) (PP) was synthesized as layered double hydroxides-PP (LDHS-PP), whose characterization, adsorption properties and mechanisms were investigated. The maximum adsorption capacity (qm) for Cd(II) was ∼2789.58 mg/g by 1% LDHS-PP, while it was ∼1893.09 mg/g by PP, which indicated that the MoS4-LDH greatly improved the Cd(II) uptake for PP in aqueous solution. In strongly acidic conditions (∼pH 3.0), there was still a good removal efficiency of about 45.65% by the 1% LDHS-PP, while that of PP was almost zero. At pH 5.0 the removal efficiency increased to 85.17% by the 1% LDHS-PP. The sorption kinetics for the 1% LDHS-PP was described well by a pseudo-second-order kinetic model. X-ray photoelectron spectrometry (XPS) and elemental distribution maps further confirmed the presence of MoS4-LDH in the PP and most of the Cd(II) chemisorption based on the Cd-S bonding. Due to its high removal efficiency and acid resistance, LDHS-PP is a promising in-situ fixation agent for the remediation of agricultural soil polluted with Cd(II) at low pH.
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Affiliation(s)
- Mei Yang
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
| | - Liang Peng
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
| | - Anwei Chen
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
| | - Qingru Zeng
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
| | - Jihai Shao
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
| | - Si Luo
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
| | - Jidong Gu
- Department of Environmental Science & Engineering, Hunan Agricultural University, Changsha, People's Republic of China
- Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, People's Republic of China
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Jiang X, Duan Y, Zhou B, Guo Q, Wang H, Hang X, Zeng L, Jia J, Bi H. The Cyclopropane Fatty Acid Synthase Mediates Antibiotic Resistance and Gastric Colonization of Helicobacter pylori. J Bacteriol 2019; 201:e00374-19. [PMID: 31358615 DOI: 10.1128/JB.00374-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 07/24/2019] [Indexed: 01/08/2023] Open
Abstract
Cyclopropane fatty acids (CFAs) are synthetized by the addition of a methylene group from S-adenosyl-l-methionine across the carbon-carbon double bonds of unsaturated fatty acid chains of membrane phospholipids. This fatty acid cyclopropanation, catalyzed by the CFA synthase (CfaS) enzyme, occurs in many bacteria, including the human pathogen Helicobacter pylori Although the cyclopropane modification was reported to play a key role in the adaptation in response to environmental stress, its role in H. pylori remains unknown. In this study, we showed that H. pylori HP0416 encodes a functional CfaS. The enzyme was demonstrated to be required for acid resistance, antibiotic resistance, intracellular survival and mouse gastric colonization, and cell membrane integrity. Moreover, the tool compound dioctylamine, which acts as a substrate mimic, directly inhibits the CfaS function of H. pylori, resulting into sensitivity to acid stress, increased antibiotic susceptibility, and attenuated abilities to avoid macrophage killing and to colonize mouse stomachs. These results validate CfaS as a promising antibiotic target and provide new potentials for this recognized target in future anti-H. pylori drug discovery efforts.IMPORTANCE The increasing prevalence of multidrug-resistant Helicobacter pylori strains has created an urgent need for alternative therapeutic regimens that complement the current antibiotic treatment strategies for H. pylori eradication; however, this is greatly hampered due to a lack of "druggable" targets. Although the CFAs are present in H. pylori cytoplasmic membranes at high levels, their physiological role has not been established. In this report, deletion of the CFA synthase CfaS was shown to attenuate acid and drug resistance, immune escape, and gastric colonization of H. pylori These findings were validated by inhibition of the CfaS activity with the tool compound dioctylamine. These studies identify this enzyme as an attractive target for further drug discovery efforts against H. pylori.
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Zhou Z, Liu Y, Zanaroli G, Wang Z, Xu P, Tang H. Enhancing Bioremediation Potential of Pseudomonas putida by Developing Its Acid Stress Tolerance With Glutamate Decarboxylase Dependent System and Global Regulator of Extreme Radiation Resistance. Front Microbiol 2019; 10:2033. [PMID: 31551970 PMCID: PMC6738132 DOI: 10.3389/fmicb.2019.02033] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/19/2019] [Indexed: 12/18/2022] Open
Abstract
The extensive use of acids in a variety of manufacturing industries results in the increase of discharged acidic waste stream into the environment. Such co-pollution of acids and other organic pollutants limits the biodegradation capability of neutrophilic degraders. With high-throughput genetic techniques, we aim to improve the acid tolerance of a pollutant-degrading bacterium, Pseudomonas putida S16 by genetically engineering it with the glutamate decarboxylase (GAD)-dependent system and the global regulator (IrrE) of extreme radiation resistance. The engineered strains holding either GAD system or irrE regulator could grow under pH 4.5, compared to the wild type. They could also degrade over 90% of a selected pollutant (benzoate or nicotine) under pH 5.0 in 48 h, while no biodegradation was detected with the wild type under the same conditions. We conclude that acid stress tolerance by the possession of the GAD system or IrrE regulator in pollutant-degrading bacteria would be a promising approach to enhance their viability and biodegrading activities in bioremediation of acidic wastes.
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Affiliation(s)
- Zikang Zhou
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai, China
| | - Yuping Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai, China
| | - Giulio Zanaroli
- Department of Civil, Chemical, Environmental and Materials Engineering - DICAM, University of Bologna, Bologna, Italy
| | | | - Ping Xu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai, China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.,Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai, China
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Yang H, Yu Y, Fu C, Chen F. Bacterial Acid Resistance Toward Organic Weak Acid Revealed by RNA-Seq Transcriptomic Analysis in Acetobacter pasteurianus. Front Microbiol 2019; 10:1616. [PMID: 31447789 PMCID: PMC6691051 DOI: 10.3389/fmicb.2019.01616] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 06/28/2019] [Indexed: 11/29/2022] Open
Abstract
Under extreme acidic environments, bacteria exploit several acid resistance (AR) mechanisms for enhancing their survival, which is concerned with several aspects, such as issues in human health and fermentation for acidic products. Currently, knowledge of bacterial AR mainly comes from the strong acid (such as hydrochloric acid) stresses, whereas AR mechanisms against organic weak acids (such as acetic acid), which are indeed encountered by bacteria, are less understood. Acetic acid bacteria (AAB), with the ability to produce acetic acid up to 20 g/100 mL, possess outstanding acetic acid tolerance, which is conferred by their unique AR mechanisms, including pyrroloquinoline quinine-dependent alcohol dehydrogenase, acetic acid assimilation and molecular chaperons. The distinguished AR of AAB toward acetic acid may provide a paradigm for research in bacterial AR against weak organic acids. In order to understand AAB’s AR mechanism more holistically, omics approaches have been employed in the corresponding field. However, the currently reported transcriptomic study was processed under a low-acidity (1 g/100 mL) environment, which could not reflect the general conditions that AAB are usually faced with. This study performed RNA-Seq transcriptomic analysis investigating AR mechanisms in Acetobacter pasteurianus CGMCC 1.41, a widely used vinegar-brewing AAB strain, at different stages of fermentation, namely, under different acetic acid concentrations (from 0.6 to 6.03 g/100 mL). The results demonstrated the even and clustered genomic distribution of up- and down-regulated genes, respectively. Difference in AR between AAB and other microorganisms was supported by the down-regulation of urea degradation and trehalose synthesis-related genes in response to acetic acid. Detailed analysis reflected the role of ethanol respiration as the main energy source and the limited effect of acetic acid assimilation on AR during fermentation as well as the competition between ethanol respiratory chain and NADH, succinate dehydrogenase-based common respiratory chain. Molecular chaperons contribute to AR, too, but their regulatory mechanisms require further investigation. Moreover, pathways of glucose catabolism and fatty acid biosynthesis are also related to AR. Finally, 2-methylcitrate cycle was proposed as an AR mechanism in AAB for the first time. This study provides new insight into AR mechanisms of AAB, and it also indicates the existence of numerous undiscovered AR mechanisms.
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Affiliation(s)
- Haoran Yang
- Hubei International Scientific and Technological Cooperation Base of Traditional Fermented Foods, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yongjian Yu
- Jiangsu Hengshun Vinegar Industry Co., Ltd., Zhenjiang, China
| | - Caixia Fu
- Hubei Tulaohan Flavouring and Food Co., Ltd., Yichang, China
| | - Fusheng Chen
- Hubei International Scientific and Technological Cooperation Base of Traditional Fermented Foods, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
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Xu J, Li T, Gao Y, Deng J, Gu J. MgrB affects the acid stress response of Escherichia coli by modulating the expression of iraM. FEMS Microbiol Lett 2019; 366:fnz123. [PMID: 31158277 DOI: 10.1093/femsle/fnz123] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 06/01/2019] [Indexed: 10/18/2023] Open
Abstract
Although MgrB is established to be a feedback inhibitor of the PhoP/Q system in Escherichia coli, the biological functions of MgrB remain largely unknown. To explore new functions of MgrB, a comparative transcriptome analysis was performed (E. coli K-12 W3110 ΔmgrB vs E. coli K-12 W3110). The results showed that many genes involved in acid stress are upregulated, suggesting that MgrB is related to acid sensitivity in E. coli. The survival rates under acid stress of the ΔmgrB mutant and wild-type showed that deletion of mgrB resulted in acid resistance. According to previous research, we deleted phoP, phoQ and iraM in the ΔmgrB mutant, and found that further deletion of phoP/phoQ only partially restored acid sensitivity. Additionally, we found that deletion of mgrB resulted in increased accumulation of RpoS during the exponential growth phase, which could be blocked by further deletion of iraM. Mutation of iraM or rpoS completely suppressed the effect of mgrB mutation on acid resistance. Taken together, the data suggest that MgrB affects the acid resistance of E. coli by modulating the expression of iraM, but not completely through PhoP/Q. This indicates that MgrB may have other protein interactors aside from PhoQ, which merits further investigation.
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Affiliation(s)
- Jintian Xu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Ting Li
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Yunrong Gao
- The Joint Center of Translational Precision Medicine, Guangzhou Institute of Pediatrics, Guangzhou Women and Children Medical Center, Guangzhou 510623, China
| | - Jiaoyu Deng
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
- Guangdong Province Key Laboratory of TB Systems Biology and Translational Medicine, Foshan Institude of Industrial Technology, Chinese Academic of Sciences, Foshan 528000, China
| | - Jing Gu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
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Pepper SJ, Britz ML. An Acid Up-Regulated Surface Protein of Lactobacillus paracasei Strain GCRL 46 is Phylogenetically Related to the Secreted Glucan- (GpbB) and Immunoglobulin-Binding (SibA) Protein of Pathogenic Streptococci. Int J Mol Sci 2019; 20:E1610. [PMID: 30935131 DOI: 10.3390/ijms20071610] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/22/2019] [Accepted: 03/28/2019] [Indexed: 02/07/2023] Open
Abstract
Bacterial cell wall hydrolases, including amidases and peptidases, play a critical role in peptidoglycan turnover during growth, impacting daughter cell separation, and cell death, through autolysis. When exploring the regulation of protein expression across the growth cycle of an acid-resistant strain of Lactobacillus paracasei, GCRL 46, we observed temporal up-regulation of proteins in the 40⁻45 kDa molecular weight range for whole-cell extracts when culturing in fermenters at a controlled pH of 4.0 versus optimum growth pH of 6.3. Up-regulation of proteins in this size range was not detected in SDS-PAGE gels of the cytosolic fraction, but was routinely detected following growth at low pH in whole cells and cell debris obtained after bead beating and centrifugation, indicating a cell surface location. N-terminal sequencing and in silico analyses showed sequence similarity with proteins in the L. casei group (L. casei, L. paracasei and L. rhamnosus) which were variously annotated as uncharacterized proteins, surface antigens, possible TrsG proteins, CHAP (cysteine, histidine-dependent amidohydrolases/peptidases)-domain proteins or putative peptidoglycan d,l-endopeptidase due to the presence of a CwlO domain. This protein is a homologue of the p40 (Msp2) secreted protein of L. rhamnosus LGG, which is linked to probiotic functionality in this species, and is phylogenetically related to structurally-similar proteins found in Enterococcus, Streptococcus and Bifidobacterium species, including the glucan-binding (GbpB), surface antigen (SagA) proteins detected in pathogenic group A streptococci species as secreted, immunoglobulin-binding (SibA) proteins (also named PcsB). Three-dimensional (3D) modelling predicted structural similarities in the CHAP proteins from the L. casei group and streptococcal species, indicating retention of overall architecture despite sequence divergence, and an implied retention of function during evolution. A phylogenetically-related hydrolase also contained the CwlO domain with a NLPC_P60 domain, and showed similar overall but distinct architecture to the CHAP proteins. We concluded that the surface-located, CHAP protein in L. casei is up-regulated during long-term exposure to acidic conditions during growth but not during acid shock.
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Van Nguyen C, Lambert P, Hung Tran Q. Effect of Vietnamese Fly Ash on Selected Physical Properties, Durability and Probability of Corrosion of Steel in Concrete. Materials (Basel) 2019; 12:ma12040593. [PMID: 30781510 PMCID: PMC6416552 DOI: 10.3390/ma12040593] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/07/2019] [Accepted: 02/13/2019] [Indexed: 11/29/2022]
Abstract
Vietnamese fly ash was used as a partial replacement for ordinary Portland cement in the proportions of 10%, 20% and 40%, while the water to cementitious ratios were kept constant at 0.42, 0.5 and 0.55, respectively, for three groups. The compressive strengths of all mixes were determined up to 90 days. The acid resistance of fly ash concrete was examined by the mass loss and compressive strength loss of 100 × 100 × 100 mm3 cubes immersed in a 10% H2SO4 solution. The probability of steel corrosion in the fly ash concrete was assessed by measuring the half-cell potentials of steel bars within beams dimensions of 100 × 100 × 500 mm3, and the flexural strengths of these beams after 300 days of immersion in a 5% NaCl solution were determined. The results demonstrate that the compressive strength of fly ash concrete is reduced at an early age but increases as the concrete continues to hydrate. The fly ash increases the sulfuric acid resistance of concrete. Fly ash additions have only a limited effect on reducing the risk of probability of corrosion of steel in the concrete. The load capacities of 10% and 20% fly ash reinforced concrete beams are higher than that of the control beams after 300 days immersed in a 5% NaCl solution.
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Affiliation(s)
- Chinh Van Nguyen
- University of Science and Technology, The University of Danang, 54 Nguyen Luong Bang, Danang, Vietnam.
| | - Paul Lambert
- Materials and Corrosion Technology, Mott MacDonald, Altrincham WA14 1ES, UK.
| | - Quang Hung Tran
- University of Science and Technology, The University of Danang, 54 Nguyen Luong Bang, Danang, Vietnam.
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66
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Feng Y, Zhong L, Bilal M, Tan Z, Hou Y, Jia S, Cui J. Enzymes@ZIF-8 Nanocomposites with Protection Nanocoating: Stability and Acid-Resistant Evaluation. Polymers (Basel) 2018; 11:E27. [PMID: 30960011 PMCID: PMC6401926 DOI: 10.3390/polym11010027] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/14/2018] [Accepted: 12/20/2018] [Indexed: 01/18/2023] Open
Abstract
Zeolitic imidazole framework-8 (ZIF-8) with tunable pore sizes and high surface areas have recently emerged as a promising support for immobilizing enzymes. However, the instability in the aqueous acidic environment and difficulty of recovery has limited their practical applications in some cases. In this study, catalase/ZIF-8 composites with a protective nanocoating were prepared by the controlled self-assembly of silanes or coordination complexes (tannic acid (TA) and Fe3+). The properties of the catalase (CAT)/ZIF-8 composites with a protective nanocoating were also determined. The recovered activity of CAT/ZIF-8 and CAT/ZIF-8 with protective nanocoating was 70% and 65%, respectively. Compared with the conventional CAT/ZIF-8 composites, CAT/ZIF-8 with protective nanocoating exhibited excellent acid resistance. For example, after treatment for 60 min in phosphate buffer solution (pH 3.0), CAT/ZIF-8 composites only maintained 20% of their initial activity (about 12 U/mg). However, CAT/ZIF-8 with a protective nanocoating could still retain about 50% of its initial activity (about 10 U/mg). Meanwhile, the thermostability and storage stability of the CAT/ZIF-8 composites was enhanced significantly due to the presence of nanocoating compared with conventional CAT/ZIF-8. More importantly, the CAT/ZIF-8 with a protective nanocoating retained 40% of its initial activity after 7 cycles, whereas CAT/ZIF-8 only retained 8% of the initial activity. The approach in this study could be an efficient strategy to prepare enzyme/ZIF-8 composites with both high acid resistance and excellent recyclability.
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Affiliation(s)
- Yuxiao Feng
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, No 29, 13th, Avenue, Tianjin Economic and Technological Development Area (TEDA), Tianjin 300457, China.
| | - Le Zhong
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, No 29, 13th, Avenue, Tianjin Economic and Technological Development Area (TEDA), Tianjin 300457, China.
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China.
| | - Zhilei Tan
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, No 29, 13th, Avenue, Tianjin Economic and Technological Development Area (TEDA), Tianjin 300457, China.
| | - Ying Hou
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, No 29, 13th, Avenue, Tianjin Economic and Technological Development Area (TEDA), Tianjin 300457, China.
| | - Shiru Jia
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, No 29, 13th, Avenue, Tianjin Economic and Technological Development Area (TEDA), Tianjin 300457, China.
| | - Jiandong Cui
- State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, No 29, 13th, Avenue, Tianjin Economic and Technological Development Area (TEDA), Tianjin 300457, China.
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67
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Yu XC, Hu Y, Ding J, Li H, Jin C. Structural basis and mechanism of the unfolding-induced activation of HdeA, a bacterial acid response chaperone. J Biol Chem 2018; 294:3192-3206. [PMID: 30573682 DOI: 10.1074/jbc.ra118.006398] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/17/2018] [Indexed: 11/06/2022] Open
Abstract
The role of protein structural disorder in biological functions has gained increasing attention in the past decade. The bacterial acid-resistant chaperone HdeA belongs to a group of "conditionally disordered" proteins, because it is inactive in its well-structured state and becomes activated via an order-to-disorder transition under acid stress. However, the mechanism for unfolding-induced activation remains unclear because of a lack of experimental information on the unfolded state conformation and the chaperone-client interactions. Herein, we used advanced solution NMR methods to characterize the activated-state conformation of HdeA under acidic conditions and identify its client-binding sites. We observed that the structure of activated HdeA becomes largely disordered and exposes two hydrophobic patches essential for client interactions. Furthermore, using the pH-dependent chemical exchange saturation transfer (CEST) NMR method, we identified three acid-sensitive regions that act as structural locks in regulating the exposure of the two client-binding sites during the activation process, revealing a multistep activation mechanism of HdeA's chaperone function at the atomic level. Our results highlight the role of intrinsic protein disorder in chaperone function and the self-inhibitory role of ordered structures under nonstress conditions, offering new insights for improving our understanding of protein structure-function paradigms.
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Affiliation(s)
- Xing-Chi Yu
- From the College of Chemistry and Molecular Engineering.,Beijing Nuclear Magnetic Resonance Center
| | - Yunfei Hu
- From the College of Chemistry and Molecular Engineering, .,Beijing Nuclear Magnetic Resonance Center
| | - Jienv Ding
- Beijing Nuclear Magnetic Resonance Center.,College of Life Sciences
| | - Hongwei Li
- From the College of Chemistry and Molecular Engineering.,Beijing Nuclear Magnetic Resonance Center
| | - Changwen Jin
- From the College of Chemistry and Molecular Engineering, .,Beijing Nuclear Magnetic Resonance Center.,College of Life Sciences.,Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
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68
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Ceballos-Jiménez AY, Rodríguez-Vilchis LE, Contreras-Bulnes R, Alatorre JÁA, Velazquez-Enriquez U, García-Fabila MM. Acid resistance of dental enamel treated with remineralizing agents, Er:YAG laser and combined treatments. Dent Med Probl 2018; 55:255-259. [PMID: 30328302 DOI: 10.17219/dmp/93960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND It has been reported that lasers can increase resistance to enamel acids, and when it is associated with fluoride, both are reported to work in synergy, achieving a reduction of the solubility of enamel. Currently, other remineralizing agents have been shown to effectively inhibit enamel demineralization. OBJECTIVES The aim of the study was to evaluate acid resistance in the occlusal surface of permanent teeth, treated with remineralizing agents, erbium-doped yttrium aluminum garnet (Er:YAG) laser and combined treatments. MATERIAL AND METHODS Eighty samples of enamel were randomly assigned to 8 groups (n = 10): a control group, and groups treated with sodium fluoride (NaF), casein phosphopeptide-amorphous calcium phosphate with NaF (CPP-ACPF), hydroxyapatite-NaF-xylitol (HA-NaF-X), Er:YAG laser (L), L+NaF, L+CPP-ACPF, and L+HA-NaF-X. The samples were placed in an acid solution and the released calcium (Ca) was quantified by atomic absorption spectrometry. RESULTS In the groups treated with NaF and L+NaF, a lower loss of Ca was observed - 15.27 ±5.17 mg/L and 15.20 ±3.85 mg/L, respectively - compared to the control group, which had the highest Ca loss: 21.93 ±13.24 mg/L. CONCLUSIONS Although the combination of Er:YAG laser plus NaF and the single application of NaF showed values suggesting superior resistance to demineralization of dental enamel compared to all the other groups in the study, no statistically significant differences were found to support this assertion.
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Affiliation(s)
- Alma Y Ceballos-Jiménez
- Advanced Studies and Research Center, Faculty of Dentistry, Autonomous University of the State of Mexico, Toluca, Mexico
| | - Laura E Rodríguez-Vilchis
- Advanced Studies and Research Center, Faculty of Dentistry, Autonomous University of the State of Mexico, Toluca, Mexico
| | - Rosalía Contreras-Bulnes
- Advanced Studies and Research Center, Faculty of Dentistry, Autonomous University of the State of Mexico, Toluca, Mexico
| | - Jesús Á Arenas Alatorre
- Department of Condensed Matter, Institute of Physics, National Autonomous University of Mexico, Mexico City, Mexico
| | - Ulises Velazquez-Enriquez
- Advanced Studies and Research Center, Faculty of Dentistry, Autonomous University of the State of Mexico, Toluca, Mexico
| | - Maria M García-Fabila
- Instrumental Analysis Laboratory, Institute of Chemistry, Autonomous University of the State of Mexico, Toluca, Mexico
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69
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Zhang B, Ran L, Wu M, Li Z, Jiang J, Wang Z, Cheng S, Fu J, Liu X. Shigellaflexneri Regulator SlyA Controls Bacterial Acid Resistance by Directly Activating the Glutamate Decarboxylation System. Front Microbiol 2018; 9:2071. [PMID: 30233544 PMCID: PMC6128205 DOI: 10.3389/fmicb.2018.02071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/14/2018] [Indexed: 01/02/2023] Open
Abstract
Shigella flexneri is an important foodborne bacterial pathogen with infectious dose as low as 10–100 cells. SlyA, a transcriptional regulator of the MarR family, has been shown to regulate virulence in a closely related bacterial pathogen, Salmonella Typhimurium. However, the regulatory role of SlyA in S. flexneri is less understood. Here we applied unbiased proteomic profiling to define the SlyA regulon in S. flexneri. We found that the genetic ablation of slyA led to the alteration of 18 bacterial proteins among over 1400 identifications. Intriguingly, most down-regulated proteins (whose expression is SlyA-dependent) were associated with bacterial acid resistance such as the glutamate decarboxylation system. We further demonstrated that SlyA directly regulates the expression of GadA, a glutamate decarboxylase, by binding to the promotor region of its coding gene. Importantly, overexpression of GadA was able to rescue the survival defect of the ΔslyA mutant under acid stress. Therefore, our study highlights a major role of SlyA in controlling S. flexneri acid resistance and provides a molecular mechanism underlying such regulation as well.
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Affiliation(s)
- Buyu Zhang
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Longhao Ran
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Mei Wu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Zezhou Li
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Jiezhang Jiang
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Zhen Wang
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Sen Cheng
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Jiaqi Fu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Xiaoyun Liu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
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70
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Liu MM, Boinett CJ, Chan ACK, Parkhill J, Murphy MEP, Gaynor EC. Investigating the Campylobacter jejuni Transcriptional Response to Host Intestinal Extracts Reveals the Involvement of a Widely Conserved Iron Uptake System. mBio 2018; 9:e01347-18. [PMID: 30087169 PMCID: PMC6083913 DOI: 10.1128/mbio.01347-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 06/27/2018] [Indexed: 12/20/2022] Open
Abstract
Campylobacter jejuni is a pathogenic bacterium that causes gastroenteritis in humans yet is a widespread commensal in wild and domestic animals, particularly poultry. Using RNA sequencing, we assessed C. jejuni transcriptional responses to medium supplemented with human fecal versus chicken cecal extracts and in extract-supplemented medium versus medium alone. C. jejuni exposed to extracts had altered expression of 40 genes related to iron uptake, metabolism, chemotaxis, energy production, and osmotic stress response. In human fecal versus chicken cecal extracts, C. jejuni displayed higher expression of genes involved in respiration (fdhTU) and in known or putative iron uptake systems (cfbpA, ceuB, chuC, and CJJ81176_1649-1655 [here designated 1649-1655]). The 1649-1655 genes and downstream overlapping gene 1656 were investigated further. Uncharacterized homologues of this system were identified in 33 diverse bacterial species representing 6 different phyla, 21 of which are associated with human disease. The 1649 and 1650 (p19) genes encode an iron transporter and a periplasmic iron binding protein, respectively; however, the role of the downstream 1651-1656 genes was unknown. A Δ1651-1656 deletion strain had an iron-sensitive phenotype, consistent with a previously characterized Δp19 mutant, and showed reduced growth in acidic medium, increased sensitivity to streptomycin, and higher resistance to H2O2 stress. In iron-restricted medium, the 1651-1656 and p19 genes were required for optimal growth when using human fecal extracts as an iron source. Collectively, this implicates a function for the 1649-1656 gene cluster in C. jejuni iron scavenging and stress survival in the human intestinal environment.IMPORTANCE Direct comparative studies of C. jejuni infection of a zoonotic commensal host and a disease-susceptible host are crucial to understanding the causes of infection outcome in humans. These studies are hampered by the lack of a disease-susceptible animal model reliably displaying a similar pathology to human campylobacteriosis. In this work, we compared the phenotypic and transcriptional responses of C. jejuni to intestinal compositions of humans (disease-susceptible host) and chickens (zoonotic host) by using human fecal and chicken cecal extracts. The mammalian gut is a complex and dynamic system containing thousands of metabolites that contribute to host health and modulate pathogen activity. We identified C. jejuni genes more highly expressed during exposure to human fecal extracts in comparison to chicken cecal extracts and differentially expressed in extracts compared with medium alone, and targeted one specific iron uptake system for further molecular, genetic, and phenotypic study.
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Affiliation(s)
- Martha M Liu
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Christine J Boinett
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Anson C K Chan
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Julian Parkhill
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Michael E P Murphy
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Erin C Gaynor
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
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Liu H, Liu W, Tan Z, Zeng Z, Yang H, Luo S, Wang L, Xi T, Xing Y. Promoting Immune Efficacy of the Oral Helicobacter pylori Vaccine by HP55/PBCA Nanoparticles against the Gastrointestinal Environment. Mol Pharm 2018; 15:3177-3186. [PMID: 30011213 DOI: 10.1021/acs.molpharmaceut.8b00251] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The immunogenicity of oral subunit vaccines is poor partly as a result of the harsh milieu of the gastrointestinal (GI) tract. For some pathogens that restrictedly inhabit the GI tract, a vaccine that works in situ may provide more potent protection than vaccines that operate parenterally. Yet, no appropriate delivery system is available for oral subunit vaccines. In this study, we designed HP55/poly( n-butylcyanoacrylate) (PBCA) nanoparticles (NPs) to carry Helicobacter pylori ( H. pylori) subunit vaccine CCF for oral administration in a prophylactic mice model. These NPs, which are synthesized using an interfacial polymerization method, protected the CCF antigen not only from the acidic pH in simulated gastric fluid (SGF, pH 1.2) but also from the proteolysis in simulated intestinal fluid (SIF, pH 7.4). Oral vaccination of mice with HP55/PBCA-CCF NPs promoted the production of serum antigen-specific antibodies, mucosal secretory IgA, and proinflammatory cytokines. Moreover, a Th1/Th17 response and augmented lymphocytes were found in the gastric tissue of HP55/PBCA-CCF NP-immunized mice, which might eventually limit H. pylori colonization. Collectively, these results indicate that HP55/PBCA NPs are promising carriers against the severe situation of the GI tract and thereby may be further utilized for other orally administrated vaccines or drugs.
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Affiliation(s)
- Hai Liu
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Wei Liu
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Zhoulin Tan
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Zhiqin Zeng
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Huimin Yang
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Shuanghui Luo
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Linlin Wang
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Tao Xi
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
| | - Yingying Xing
- School of Life Science and Technology and Jiangsu Key Laboratory of Carcinogenesis and Intervention , China Pharmaceutical University , No.24 Tongjia xiang , Nanjing 210009 , PR China
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72
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Li MF, Sun L. Edwardsiella tarda Sip2: A Serum-Induced Protein That Is Essential to Serum Survival, Acid Resistance, Intracellular Replication, and Host Infection. Front Microbiol 2018; 9:1084. [PMID: 29887847 PMCID: PMC5980991 DOI: 10.3389/fmicb.2018.01084] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Edwardsiella tarda is a broad-host pathogen that can infect mammals, reptiles, and fish. E. tarda exhibits a remarkable ability to survive in host serum and replicate in host phagocytes, but the underlining mechanism is unclear. In this study, in order to identify E. tarda proteins involved in serum resistance, iTRAQ proteomic analysis was performed to examine the whole-cell protein profiles of TX01, a pathogenic E. tarda isolate, in response to serum treatment. Of the differentially expressed proteins identified, one (named Sip2) possesses a conserved hydrogenase domain and is homologous to the putative hydrogenase accessory protein HypB. When Sip2 was expressed in Escherichia coli, it significantly enhanced the survival of the host cells in serum. Compared to TX01, the sip2 knockout, TX01Δsip2, was dramatically reduced in the ability of hydrogenase activity, serum resistance, intracellular replication, dissemination in fish tissues, and causing mortality in infected fish. The lost virulence capacities of TX01Δsip2 were restored by complementation with the sip2 gene. Furthermore, TX01Δsip2 was significantly reduced in the capacity to grow under low pHs and iron-depleted conditions, and was unable to maintain its internal pH in acidic environment. Taken together, these results indicate that Sip2 is a novel serum-induced protein that is essential to serum resistance, cellular and tissue infection, and coping with acidic stress via its ability to modulate intracellular pH.
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Affiliation(s)
- Mo-fei Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Li Sun
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
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Ilgü H, Jeckelmann JM, Colas C, Ucurum Z, Schlessinger A, Fotiadis D. Effects of Mutations and Ligands on the Thermostability of the l-Arginine/Agmatine Antiporter AdiC and Deduced Insights into Ligand-Binding of Human l-Type Amino Acid Transporters. Int J Mol Sci 2018; 19:ijms19030918. [PMID: 29558430 PMCID: PMC5877779 DOI: 10.3390/ijms19030918] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 01/09/2023] Open
Abstract
The l-arginine/agmatine transporter AdiC is a prokaryotic member of the SLC7 family, which enables pathogenic enterobacteria to survive the extremely acidic gastric environment. Wild-type AdiC from Escherichia coli, as well as its previously reported point mutants N22A and S26A, were overexpressed homologously and purified to homogeneity. A size-exclusion chromatography-based thermostability assay was used to determine the melting temperatures (Tms) of the purified AdiC variants in the absence and presence of the selected ligands l-arginine (Arg), agmatine, l-arginine methyl ester, and l-arginine amide. The resulting Tms indicated stabilization of AdiC variants upon ligand binding, in which Tms and ligand binding affinities correlated positively. Considering results from this and previous studies, we revisited the role of AdiC residue S26 in Arg binding and proposed interactions of the α-carboxylate group of Arg exclusively with amide groups of the AdiC backbone. In the context of substrate binding in the human SLC7 family member l-type amino acid transporter-1 (LAT1; SLC7A5), an analogous role of S66 in LAT1 to S26 in AdiC is discussed based on homology modeling and amino acid sequence analysis. Finally, we propose a binding mechanism for l-amino acid substrates to LATs from the SLC7 family.
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Affiliation(s)
- Hüseyin Ilgü
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, CH-3012 Bern, Switzerland.
| | - Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, CH-3012 Bern, Switzerland.
| | - Claire Colas
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Zöhre Ucurum
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, CH-3012 Bern, Switzerland.
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, CH-3012 Bern, Switzerland.
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Vecchione A, Celandroni F, Mazzantini D, Senesi S, Lupetti A, Ghelardi E. Compositional Quality and Potential Gastrointestinal Behavior of Probiotic Products Commercialized in Italy. Front Med (Lausanne) 2018; 5:59. [PMID: 29564327 PMCID: PMC5845905 DOI: 10.3389/fmed.2018.00059] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/19/2018] [Indexed: 01/21/2023] Open
Abstract
Recent guidelines indicate that oral probiotics, living microorganisms able to confer a health benefit on the host, should be safe for human consumption, when administered in a sufficient amount, and resist acid and bile to exert their beneficial effects (e.g., metabolic, immunomodulatory, anti-inflammatory, competitive). This study evaluated quantitative and qualitative aspects and the viability in simulated gastric and intestinal juices of commercial probiotic formulations available in Italy. Plate counting and MALDI-TOF mass spectrometry were used to enumerate and identify the contained organisms. In vitro studies with two artificial gastric juices and pancreatin-bile salt solution were performed to gain information on the gastric tolerance and bile resistance of the probiotic formulations. Most preparations satisfied the requirements for probiotics and no contaminants were found. Acid resistance and viability in bile were extremely variable depending on the composition of the formulations in terms of contained species and strains. In conclusion, this study indicates good microbiological quality but striking differences in the behavior in the presence of acids and bile for probiotic formulations marketed in Italy.
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Affiliation(s)
- Alessandra Vecchione
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Francesco Celandroni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Diletta Mazzantini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Sonia Senesi
- Department of Biology, University of Pisa, Pisa, Italy
| | - Antonella Lupetti
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Emilia Ghelardi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy,Research Center Nutraceuticals and Food for Health-Nutrafood, University of Pisa, Pisa, Italy,*Correspondence: Emilia Ghelardi,
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李 转, 许 晓, 陈 璇, 吴 昕, 赵 望. [Role of SMU.2055 gene in regulating acid resistance of Streptococcus mutans UA159]. Nan Fang Yi Ke Da Xue Xue Bao 2018; 38:198-204. [PMID: 29502060 PMCID: PMC6743886 DOI: 10.3969/j.issn.1673-4254.2018.02.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Indexed: 06/08/2023]
Abstract
OBJECTIVE To evaluate the effect of SMU.2055 gene on acid resistance of Streptococcus mutans. METHODS A SMU.2055-dificient mutant strain of S. mutans was constructed using homologous recombination technique. The growth of the wild-type and mutant strains was monitored in both normal and acidic conditions. The lethal pH level, glycolysis, proton permeability, cell permeability and biofilm formation of the two strains were compared. RESULTS PCR and sequence analyses verified the successful construction of the SMU.2055-dificient mutant strain. The growth and biofilm formation capacity of the mutant strain were obviously lowered in both normal and acidic conditions. The mutant strain also showed increased lethal pH level, proton permeability, and cell permeability with impaired H+-ATPase activity in acidic conditions, but its minimum glycolytic pH remained unaffected. CONCLUSION The SMU.2055-deficient S. mutans mutant exhibits a lowered acid resistance, which affects the growth, lethal pH, proton permeability, H+-ATPase activity, cell permeability and biofilm formation but not the minimum glycolytic pH of the mutant strain.
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Affiliation(s)
- 转玲 李
- 南方医科大学南方医院口腔科,广东 广州 510515Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - 晓虎 许
- 深圳市龙华新区中心医院口腔科,广东 深圳 518110Department of Stomatology, Longhua New District Central Hospital, Shenzhen 518110, China
| | - 璇 陈
- 南方医科大学口腔医院,广东 广州 510280Stomatological Hospital, Southern Medical University, Guangzhou 510280, China
| | - 昕彧 吴
- 南方医科大学口腔医院,广东 广州 510280Stomatological Hospital, Southern Medical University, Guangzhou 510280, China
| | - 望泓 赵
- 南方医科大学南方医院口腔科,广东 广州 510515Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
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李 转, 许 晓, 陈 璇, 吴 昕, 赵 望. [Role of SMU.2055 gene in regulating acid resistance of Streptococcus mutans UA159]. Nan Fang Yi Ke Da Xue Xue Bao 2018; 38:198-204. [PMID: 29502060 PMCID: PMC6743886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Indexed: 10/15/2023]
Abstract
OBJECTIVE To evaluate the effect of SMU.2055 gene on acid resistance of Streptococcus mutans. METHODS A SMU.2055-dificient mutant strain of S. mutans was constructed using homologous recombination technique. The growth of the wild-type and mutant strains was monitored in both normal and acidic conditions. The lethal pH level, glycolysis, proton permeability, cell permeability and biofilm formation of the two strains were compared. RESULTS PCR and sequence analyses verified the successful construction of the SMU.2055-dificient mutant strain. The growth and biofilm formation capacity of the mutant strain were obviously lowered in both normal and acidic conditions. The mutant strain also showed increased lethal pH level, proton permeability, and cell permeability with impaired H+-ATPase activity in acidic conditions, but its minimum glycolytic pH remained unaffected. CONCLUSION The SMU.2055-deficient S. mutans mutant exhibits a lowered acid resistance, which affects the growth, lethal pH, proton permeability, H+-ATPase activity, cell permeability and biofilm formation but not the minimum glycolytic pH of the mutant strain.
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Affiliation(s)
- 转玲 李
- 南方医科大学南方医院口腔科,广东 广州 510515Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - 晓虎 许
- 深圳市龙华新区中心医院口腔科,广东 深圳 518110Department of Stomatology, Longhua New District Central Hospital, Shenzhen 518110, China
| | - 璇 陈
- 南方医科大学口腔医院,广东 广州 510280Stomatological Hospital, Southern Medical University, Guangzhou 510280, China
| | - 昕彧 吴
- 南方医科大学口腔医院,广东 广州 510280Stomatological Hospital, Southern Medical University, Guangzhou 510280, China
| | - 望泓 赵
- 南方医科大学南方医院口腔科,广东 广州 510515Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
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Goswami M, Narayana Rao AVSS. Transcriptome Profiling Reveals Interplay of Multifaceted Stress Response in Escherichia coli on Exposure to Glutathione and Ciprofloxacin. mSystems 2018; 3:e00001-18. [PMID: 29468195 DOI: 10.1128/mSystems.00001-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 01/22/2018] [Indexed: 12/16/2022] Open
Abstract
The emergence and spread of multidrug-resistant bacterial strains have serious medical and clinical consequences. In addition, the rate of discovery of new therapeutic antibiotics has been inadequate in last few decades. Fluoroquinolone antibiotics such as ciprofloxacin represent a precious therapeutic resource in the fight against bacterial pathogens. However, these antibiotics have been gradually losing their appeal due to the emergence and buildup of resistance to them. In this report, we shed light on the genome-level expression changes in bacteria with respect to glutathione (GSH) exposure which act as a trigger for fluoroquinolone antibiotic resistance. The knowledge about different bacterial stress response pathways under conditions of exposure to the conditions described above and potential points of cross talk between them could help us in understanding and formulating the conditions under which buildup and spread of antibiotic resistance could be minimized. Our findings are also relevant because GSH-induced genome-level expression changes have not been reported previously for E. coli. We have previously reported that supplementation of exogenous glutathione (GSH) promotes ciprofloxacin resistance in Escherichia coli by neutralizing antibiotic-induced oxidative stress and by enhancing the efflux of antibiotic. In the present study, we used a whole-genome microarray as a tool to analyze the system-level transcriptomic changes of E. coli on exposure to GSH and/or ciprofloxacin. The microarray data revealed that GSH supplementation affects redox function, transport, acid shock, and virulence genes of E. coli. The data further highlighted the interplay of multiple underlying stress response pathways (including those associated with the genes mentioned above and DNA damage repair genes) at the core of GSH, offsetting the effect of ciprofloxacin in E. coli. The results of a large-scale validation of the transcriptomic data using reverse transcription-quantitative PCR (RT-qPCR) analysis for 40 different genes were mostly in agreement with the microarray results. The altered growth profiles of 12 different E. coli strains carrying deletions in the specific genes mentioned above with GSH and/or ciprofloxacin supplementation implicate these genes in the GSH-mediated phenotype not only at the molecular level but also at the functional level. We further associated GSH supplementation with increased acid shock survival of E. coli on the basis of our transcriptomic data. Taking the data together, it can be concluded that GSH supplementation influences the expression of genes of multiple stress response pathways apart from its effect(s) at the physiological level to counter the action of ciprofloxacin in E. coli. IMPORTANCE The emergence and spread of multidrug-resistant bacterial strains have serious medical and clinical consequences. In addition, the rate of discovery of new therapeutic antibiotics has been inadequate in last few decades. Fluoroquinolone antibiotics such as ciprofloxacin represent a precious therapeutic resource in the fight against bacterial pathogens. However, these antibiotics have been gradually losing their appeal due to the emergence and buildup of resistance to them. In this report, we shed light on the genome-level expression changes in bacteria with respect to glutathione (GSH) exposure which act as a trigger for fluoroquinolone antibiotic resistance. The knowledge about different bacterial stress response pathways under conditions of exposure to the conditions described above and potential points of cross talk between them could help us in understanding and formulating the conditions under which buildup and spread of antibiotic resistance could be minimized. Our findings are also relevant because GSH-induced genome-level expression changes have not been reported previously for E. coli.
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78
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Freddi L, Damiano MA, Chaloin L, Pennacchietti E, Al Dahouk S, Köhler S, De Biase D, Occhialini A. The Glutaminase-Dependent System Confers Extreme Acid Resistance to New Species and Atypical Strains of Brucella. Front Microbiol 2017; 8:2236. [PMID: 29187839 PMCID: PMC5695133 DOI: 10.3389/fmicb.2017.02236] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/31/2017] [Indexed: 11/28/2022] Open
Abstract
Neutralophilic bacteria have developed specific mechanisms to cope with the acid stress encountered in environments such as soil, fermented foods, and host compartments. In Escherichia coli, the glutamate decarboxylase (Gad)-dependent system is extremely efficient: it requires the concerted action of glutamate decarboxylase (GadA/GadB) and of the glutamate (Glu)/γ-aminobutyrate antiporter, GadC. Notably, this system is operative also in new strains/species of Brucella, among which Brucella microti, but not in the “classical” species, with the exception of marine mammals strains. Recently, the glutaminase-dependent system (named AR2_Q), relying on the deamination of glutamine (Gln) into Glu and on GadC activity, was described in E. coli. In Brucella genomes, a putative glutaminase (glsA)-coding gene is located downstream of the gadBC genes. We found that in B. microti these genes are expressed as a polycistronic transcript. Moreover, using a panel of Brucella genus-representative strains, we show that the AR2_Q system protects from extreme acid stress (pH ≤2.5), in the sole presence of Gln, only the Brucella species/strains predicted to have functional glsA and gadC. Indeed, mutagenesis approaches confirmed the involvement of glsA and gadC of B. microti in AR2_Q and that the acid-sensitive phenotype of B. abortus can be ascribed to a Ser248Leu substitution in GlsA, leading to loss of glutaminase activity. Furthermore, we found that the gene BMI_II339, of unknown function and downstream of the gadBC–glsA operon, positively affects Gad- and GlsA-dependent AR. Thus, we identified novel determinants that allow newly discovered and marine mammals Brucella strains to be better adapted to face hostile acidic environments. As for significance, this work may contribute to the understanding of the host preferences of Brucella species and opens the way to alternative diagnostic targets in epidemiological surveillance of brucellosis.
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Affiliation(s)
- Luca Freddi
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Montpellier, Montpellier, France
| | - Maria A Damiano
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Montpellier, Montpellier, France
| | - Laurent Chaloin
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Montpellier, Montpellier, France
| | - Eugenia Pennacchietti
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Laboratory Affiliated to the Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Latina, Italy
| | | | - Stephan Köhler
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Montpellier, Montpellier, France
| | - Daniela De Biase
- Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Laboratory Affiliated to the Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Latina, Italy
| | - Alessandra Occhialini
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Université de Montpellier, Montpellier, France
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79
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Abstract
Group B streptococcus (GBS) is a leading cause of neonatal mortality and morbidity in the United States and Europe. It is part of the vaginal microbiota in up to 30% of pregnant women and can be passed on to the newborn through perinatal transmission. GBS has the ability to survive in multiple different host niches. The pathophysiology of this bacterium reveals an outstanding ability to withstand varying pH fluctuations of the surrounding environments inside the human host. GBS host pathogen interations include colonization of the acidic vaginal mucosa, invasion of the neutral human blood or amniotic fluid, breaching of the blood brain barrier as well as survival within the acidic phagolysosomal compartment of macrophages. However, investigations on GBS responses to acid stress are limited. Technologies, such as whole genome sequencing, genome-wide transcription and proteome mapping facilitate large scale identification of genes and proteins. Mechanisms enabling GBS to cope with acid stress have mainly been studied through these techniques and are summarized in the current review
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Affiliation(s)
- Sarah Shabayek
- Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany.,Department of Microbiology and Immunology, Faculty of Pharmacy, Suez Canal UniversityIsmailia, Egypt
| | - Barbara Spellerberg
- Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany
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80
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Abstract
Helicobacter pylori is responsible for the most commonly found infection in the world's population. It is the major risk factor for gastric cancer development. Numerous studies published over the last year provide new insights into the strategies employed by H. pylori to adapt to the extreme acidic conditions of the gastric environment, to establish persistent infection and to deregulate host functions, leading to gastric pathogenesis and cancer. In this review, we report recent data on the mechanisms involved in chemotaxis, on the essential role of nickel in acid resistance and gastric colonization, on the importance of adhesins and Hop proteins and on the role of CagPAI-components and CagA. Among the host functions, a special focus has been made on the escape from immune response, the ability of bacteria to induce genetic instability and modulate telomeres, the mechanism of autophagy and the deregulation of micro RNAs.
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Affiliation(s)
- Vania Camilo
- Pasteur Institute, Department of Microbiology, Helicobacter Pathogenesis Unit, Paris Cedex 15, France.,INSERM U1173, Faculty of Health Sciences Simone Veil, Université Versailles-Saint-Quentin, Saint Quentin en Yvelines, France
| | - Toshiro Sugiyama
- Graduate School of Medicine and Pharmaceutical Sciences, Department of Gastroenterology, University of Toyama, Sugitani, Toyama, Japan
| | - Eliette Touati
- Pasteur Institute, Department of Microbiology, Helicobacter Pathogenesis Unit, Paris Cedex 15, France
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81
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Sen H, Aggarwal N, Ishionwu C, Hussain N, Parmar C, Jamshad M, Bavro VN, Lund PA. Structural and Functional Analysis of the Escherichia coli Acid-Sensing Histidine Kinase EvgS. J Bacteriol 2017; 199:e00310-17. [PMID: 28674068 DOI: 10.1128/JB.00310-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 06/19/2017] [Indexed: 01/31/2023] Open
Abstract
The EvgS/EvgA two-component system of Escherichia coli is activated in response to low pH and alkali metals and regulates many genes, including those for the glutamate-dependent acid resistance system and a number of efflux pumps. EvgS, the sensor kinase, is one of five unconventional histidine kinases (HKs) in E. coli and has a large periplasmic domain and a cytoplasmic PAS domain in addition to phospho-acceptor, HK and dimerization, internal receiver, and phosphotransfer domains. Mutations that constitutively activate the protein at pH 7 map to the PAS domain. Here, we built a homology model of the periplasmic region of EvgS, based on the structure of the equivalent region of the BvgS homologue, to guide mutagenesis of potential key residues in this region. We show that histidine 226 is required for induction and that it is structurally colocated with a proline residue (P522) at the top of the predicted transmembrane helix that is expected to play a key role in passing information to the cytoplasmic domains. We also show that the constitutive mutations in the PAS domain can be further activated by low external pH. Expression of the cytoplasmic part of the protein alone also gives constitutive activation, which is lost if the constitutive PAS mutations are present. These findings are consistent with a model in which EvgS senses both external and internal pH and is activated by a shift from a tight inactive to a weak active dimer, and we present an analysis of the purified cytoplasmic portion of EvgS that supports this. IMPORTANCE One of the ways bacteria sense their environment is through two-component systems, which have one membrane-bound protein to do the sensing and another inside the cell to turn genes on or off in response to what the membrane-bound protein has detected. The membrane-bound protein must thus be able to detect the stress and signal this detection event to the protein inside the cell. To understand this process, we studied a protein that helps E. coli to survive exposure to low pH, which it must do before taking up residence in the gastrointestinal tract. We describe a predicted structure for the main sensing part of the protein and identify some key residues within it that are involved in the sensing and signaling processes. We propose a mechanism for how the protein may become activated and present some evidence to support our proposal.
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82
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Kay KL, Breidt F, Fratamico PM, Baranzoni GM, Kim GH, Grunden AM, Oh DH. Escherichia coli O157:H7 Acid Sensitivity Correlates with Flocculation Phenotype during Nutrient Limitation. Front Microbiol 2017; 8:1404. [PMID: 28798736 PMCID: PMC5526969 DOI: 10.3389/fmicb.2017.01404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 07/11/2017] [Indexed: 01/16/2023] Open
Abstract
Shiga toxin producing Escherichia coli (STEC) strains vary in acid resistance; however, little is known about the underlying mechanisms that result in strain specific differences. Among 25 STEC O157:H7 strains tested, 7 strains flocculated when grown statically for 18 h in minimal salts medium at 37°C, while 18 strains did not. Interestingly, the flocculation phenotype (cells came out of suspension) was found to correlate with degree of acid sensitivity in an assay with 400 mM acetic acid solution at pH 3.3 targeting acidified foods. Strains exhibiting flocculation were more acid sensitive and were designated FAS, for flocculation acid sensitive, while the acid resistant strain designated PAR for planktonic acid resistant. Flocculation was not observed for any strains during growth in complex medium (Luria Bertani broth). STEC strains B201 and B241 were chosen as representative FAS (2.4 log reduction) and PAR (0.15 log reduction) strains, respectively, due to differences in acid resistance and flocculation phenotype. Results from electron microscopy showed evidence of fimbriae production in B201, whereas fimbriae were not observed in B241.Curli fimbriae production was identified through plating on Congo red differential medium, and all FAS strains showed curli fimbriae production. Surprisingly, 5 PAR strains also had evidence of curli production. Transcriptomic and targeted gene expression data for B201 and B241indicated that csg and hde (curli and acid induced chaperone genes, respectively) expression positively correlated with the phenotypic differences observed for these strains. These data suggest that FAS strains grown in minimal medium express curli, resulting in a flocculation phenotype. This may be regulated by GcvB, which positively regulates curli fimbriae production and represses acid chaperone proteins. RpoS and other regulatory mechanisms may impact curli fimbriae production, as well. These findings may help elucidate mechanisms underlying differences among STEC strains in relating acid resistance and biofilm formation.
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Affiliation(s)
- Kathryn L. Kay
- Department of Plant and Microbial Biology, North Carolina State UniversityRaleigh, NC, United States
- Food Science Research Unit, United States Department of Agriculture-Agriculture Research ServiceRaleigh, NC, United States
| | - Frederick Breidt
- Department of Plant and Microbial Biology, North Carolina State UniversityRaleigh, NC, United States
- Food Science Research Unit, United States Department of Agriculture-Agriculture Research ServiceRaleigh, NC, United States
| | - Pina M. Fratamico
- United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research CenterWyndmoor, PA, United States
| | - Gian M. Baranzoni
- United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research CenterWyndmoor, PA, United States
| | - Gwang-Hee Kim
- United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research CenterWyndmoor, PA, United States
- Department of Food Science and Biotechnology, College of Bioscience and Biotechnology, Kangwon National UniversityChuncheon, South Korea
| | - Amy M. Grunden
- Department of Plant and Microbial Biology, North Carolina State UniversityRaleigh, NC, United States
| | - Deog-Hwan Oh
- Department of Food Science and Biotechnology, College of Bioscience and Biotechnology, Kangwon National UniversityChuncheon, South Korea
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Wu Y, Chakravarty S, Li M, Wai TT, Hoffman SL, Sim BKL. Development of a Live Attenuated Bivalent Oral Vaccine Against Shigella sonnei Shigellosis and Typhoid Fever. J Infect Dis 2017; 215:259-268. [PMID: 27803169 DOI: 10.1093/infdis/jiw528] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/24/2016] [Indexed: 11/14/2022] Open
Abstract
Shigella sonnei and Salmonella Typhi cause significant morbidity and mortality. We exploited the safety record of the oral, attenuated S. Typhi vaccine (Ty21a) by using it as a vector to develop a bivalent oral vaccine to protect against S. sonnei shigellosis and typhoid fever. We recombineered the S. sonnei form I O-antigen gene cluster into the Ty21a chromosome to create Ty21a-Ss, which stably expresses S. sonnei form I O antigen. To enhance survivability in the acid environment of the stomach, we created an acid-resistant strain, Ty21a-AR-Ss, by inserting Shigella glutaminase-glutamate decarboxylase systems coexpressed with S. sonnei form I O-antigen gene. Mice immunized intranasally with Ty21a-AR-Ss produced antibodies against S. sonnei and S. Typhi, and survived lethal intranasal S. sonnei challenge. This paves the way for proposed good manufacturing practices manufacture and clinical trials intended to test the clinical effectiveness of Ty21a-AR-Ss in protecting against S. sonnei shigellosis and typhoid fever, as compared with the current Ty21a vaccine.
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84
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Xiong G, Wu B, Wu T. Effects of Pr₆O 11 Addition on the Acid Resistance of Ceramic Proppant. Materials (Basel) 2017; 10:ma10040427. [PMID: 28772788 PMCID: PMC5506917 DOI: 10.3390/ma10040427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 11/16/2022]
Abstract
This paper investigated the effect of Pr₆O11 addition on the acid resistance of ceramic proppant. Acid resistance of proppants can be improved by introducing Pr₆O11 into the Al₂O₃-CaO-MgO-SiO₂ (ACMS) system. To illustrate and explain the mechanism of acid resistance, the samples were characterized by different techniques, using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The phase structure of the specimens was characterized by XRD and SEM-detected microstructures of the specimens. It was observed that with the increase of rare-earth oxide content, the acid solubility of the specimens decreased, and then increased when it reached the minimum value 0.45 wt %. The results of the research show that the improvement of acid resistance with rare-earth oxides was achieved by refining the grain size, strengthening the grain boundary, and turning Ca₂Al₂SiO₇, in which acid resistance is poor, into CaAl12O19, which possesses better acid resistance, and then enhance the acid resistance of the proppants. Furthermore, Pr₆O11 can form a solid solution with Ca₂Al₂SiO₇ and CaAl12O19. The acid resistance of CaAl12O19 improves with the increase of solid solubility. In contrast, the acid resistance of Ca₂Al₂SiO₇ will decrease after Ca₂Al₂SiO₇ forms a solid solution with Pr₆O11.
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Affiliation(s)
- Guodong Xiong
- College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, Guangxi, China.
| | - Bolin Wu
- College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, Guangxi, China.
| | - Tingting Wu
- College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, Guangxi, China.
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85
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Tramonti A, De Santis F, Pennacchietti E, De Biase D. The yhiM gene codes for an inner membrane protein involved in GABA export in Escherichia coli. AIMS Microbiol 2017; 3:71-87. [PMID: 31294150 PMCID: PMC6604978 DOI: 10.3934/microbiol.2017.1.71] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Accepted: 02/08/2017] [Indexed: 01/11/2023] Open
Abstract
In order to survive the exposure to acid pH, Escherichia coli activates molecular circuits leading from acid tolerance to extreme acid resistance (AR). The activation of the different circuits involves several global and specific regulators affecting the expression of membrane, periplasmic and cytosolic proteins acting at different levels to dampen the harmful consequences of the uncontrolled entry of protons intracellularly. Many genes coding for the structural components of the AR circuits (protecting from pH ≤ 2.5) and their specific transcriptional regulators cluster in a genomic region named AFI (acid fitness island) and respond in the same way to global regulators (such as RpoS and H-NS) as well as to anaerobiosis, alkaline, cold and respiratory stresses, in addition to the acid stress. Notably some genes coding for structural components of AR, though similarly regulated, are non-AFI localised. Amongst these the gadBC operon, coding for the major structural components of the glutamate-based AR system, and the ybaS gene, coding for a glutaminase required for the glutamine-based AR system. The yhiM gene, a non-AFI gene, appears to belong to this group. We mapped the transcription start of the 1.1 kb monocistronic yhiM transcript: it is an adenine residue located 22 nt upstream a GTG start codon. By real-time PCR we show that GadE and GadX equally affect the expression of yhiM under oxidative growth conditions. While YhiM is partially involved in the RpoS-dependent AR, we failed to detect a significant involvement in the glutamate- or glutamine-dependent AR at pH ≤ 2.5. However, when grown in EG at pH 5.0, the yhiM mutant displays impaired GABA export, whereas when YhiM is overexpressed, an increases of GABA export in EG medium in the pH range 2.5-5.5 is observed. Our data suggest that YhiM is a GABA transporter with a physiological role more relevant at mildly acidic pH, but not a key component of AR at pH < 2.5.
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Affiliation(s)
- Angela Tramonti
- Institute of Molecular Biology and Pathology, CNR, Department of Biochemical Sciences "A. Rossi Fanelli", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Fiorenzo De Santis
- Department of medico-surgical Sciences and Biotechnologies, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Corso della Repubblica 79, 04100 Latina, Italy
| | - Eugenia Pennacchietti
- Department of medico-surgical Sciences and Biotechnologies, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Corso della Repubblica 79, 04100 Latina, Italy
| | - Daniela De Biase
- Department of medico-surgical Sciences and Biotechnologies, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Corso della Repubblica 79, 04100 Latina, Italy
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86
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Wu Q, Tun HM, Law YS, Khafipour E, Shah NP. Common Distribution of gad Operon in Lactobacillus brevis and its GadA Contributes to Efficient GABA Synthesis toward Cytosolic Near-Neutral pH. Front Microbiol 2017; 8:206. [PMID: 28261168 PMCID: PMC5306213 DOI: 10.3389/fmicb.2017.00206] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 01/30/2017] [Indexed: 12/23/2022] Open
Abstract
Many strains of lactic acid bacteria (LAB) and bifidobacteria have exhibited strain-specific capacity to produce γ-aminobutyric acid (GABA) via their glutamic acid decarboxylase (GAD) system, which is one of amino acid-dependent acid resistance (AR) systems in bacteria. However, the linkage between bacterial AR and GABA production capacity has not been well established. Meanwhile, limited evidence has been provided to the global diversity of GABA-producing LAB and bifidobacteria, and their mechanisms of efficient GABA synthesis. In this study, genomic survey identified common distribution of gad operon-encoded GAD system in Lactobacillus brevis for its GABA production among varying species of LAB and bifidobacteria. Importantly, among four commonly distributed amino acid-dependent AR systems in Lb. brevis, its GAD system was a major contributor to maintain cytosolic pH homeostasis by consuming protons via GABA synthesis. This highlights that Lb. brevis applies GAD system as the main strategy against extracellular and intracellular acidification demonstrating its high capacity of GABA production. In addition, the abundant GadA retained its activity toward near-neutral pH (pH 5.5–6.5) of cytosolic acidity thus contributing to efficient GABA synthesis in Lb. brevis. This is the first global report illustrating species-specific characteristic and mechanism of efficient GABA synthesis in Lb. brevis.
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Affiliation(s)
- Qinglong Wu
- School of Biological Sciences, The University of Hong Kong Hong Kong, Hong Kong
| | - Hein Min Tun
- Department of Animal Science, University of Manitoba Winnipeg, MB, Canada
| | - Yee-Song Law
- School of Biological Sciences, The University of Hong Kong Hong Kong, Hong Kong
| | - Ehsan Khafipour
- Department of Animal Science, University of ManitobaWinnipeg, MB, Canada; Department of Medical Microbiology, University of ManitobaWinnipeg, MB, Canada
| | - Nagendra P Shah
- School of Biological Sciences, The University of Hong KongHong Kong, Hong Kong; Victoria UniversityMelbourne, VIC, Australia
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87
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Botella H, Vaubourgeix J, Lee MH, Song N, Xu W, Makinoshima H, Glickman MS, Ehrt S. Mycobacterium tuberculosis protease MarP activates a peptidoglycan hydrolase during acid stress. EMBO J 2017; 36:536-548. [PMID: 28057704 DOI: 10.15252/embj.201695028] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 11/28/2016] [Accepted: 12/02/2016] [Indexed: 11/09/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) can persist in the human host in a latent state for decades, in part because it has the ability to withstand numerous stresses imposed by host immunity. Prior studies have established the essentiality of the periplasmic protease MarP for Mtb to survive in acidified phagosomes and establish and maintain infection in mice. However, the proteolytic substrates of MarP that mediate these phenotypes were unknown. Here, we used biochemical methods coupled with supravital chemical probes that facilitate imaging of nascent peptidoglycan to demonstrate that during acid stress MarP cleaves the peptidoglycan hydrolase RipA, a process required for RipA's activation. Failure of RipA processing in MarP-deficient cells leads to cell elongation and chain formation, a hallmark of progeny cell separation arrest. Our results suggest that sustaining peptidoglycan hydrolysis, a process required for cell elongation, separation of progeny cells, and cell wall homeostasis in growing cells, may also be essential for Mtb's survival in acidic conditions.
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Affiliation(s)
- Helene Botella
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Julien Vaubourgeix
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Myung Hee Lee
- Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Naomi Song
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Weizhen Xu
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
| | - Hideki Makinoshima
- Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Michael S Glickman
- Division of Infectious Diseases, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
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88
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González C, Lazcano M, Valdés J, Holmes DS. Bioinformatic Analyses of Unique (Orphan) Core Genes of the Genus Acidithiobacillus: Functional Inferences and Use As Molecular Probes for Genomic and Metagenomic/Transcriptomic Interrogation. Front Microbiol 2016; 7:2035. [PMID: 28082953 PMCID: PMC5186765 DOI: 10.3389/fmicb.2016.02035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 12/02/2016] [Indexed: 01/06/2023] Open
Abstract
Using phylogenomic and gene compositional analyses, five highly conserved gene families have been detected in the core genome of the phylogenetically coherent genus Acidithiobacillus of the class Acidithiobacillia. These core gene families are absent in the closest extant genus Thermithiobacillus tepidarius that subtends the Acidithiobacillus genus and roots the deepest in this class. The predicted proteins encoded by these core gene families are not detected by a BLAST search in the NCBI non-redundant database of more than 90 million proteins using a relaxed cut-off of 1.0e−5. None of the five families has a clear functional prediction. However, bioinformatic scrutiny, using pI prediction, motif/domain searches, cellular location predictions, genomic context analyses, and chromosome topology studies together with previously published transcriptomic and proteomic data, suggests that some may have functions associated with membrane remodeling during cell division perhaps in response to pH stress. Despite the high level of amino acid sequence conservation within each family, there is sufficient nucleotide variation of the respective genes to permit the use of the DNA sequences to distinguish different species of Acidithiobacillus, making them useful additions to the armamentarium of tools for phylogenetic analysis. Since the protein families are unique to the Acidithiobacillus genus, they can also be leveraged as probes to detect the genus in environmental metagenomes and metatranscriptomes, including industrial biomining operations, and acid mine drainage (AMD).
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Affiliation(s)
- Carolina González
- Center for Bioinformatics and Genome Biology, Fundación Ciencia & VidaSantiago, Chile; Facultad de Ciencias Biologicas, Universidad Andres BelloSantiago, Chile
| | - Marcelo Lazcano
- Center for Bioinformatics and Genome Biology, Fundación Ciencia & VidaSantiago, Chile; Facultad de Ciencias Biologicas, Universidad Andres BelloSantiago, Chile
| | - Jorge Valdés
- Center for Genomics and Bioinformatics, Faculty of Sciences, Universidad Mayor Santiago, Chile
| | - David S Holmes
- Center for Bioinformatics and Genome Biology, Fundación Ciencia & VidaSantiago, Chile; Facultad de Ciencias Biologicas, Universidad Andres BelloSantiago, Chile
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89
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Krishna U, Romero-Gallo J, Suarez G, Azah A, Krezel AM, Varga MG, Forsyth MH, Peek RM. Genetic Evolution of a Helicobacter pylori Acid-Sensing Histidine Kinase and Gastric Disease. J Infect Dis 2016; 214:644-8. [PMID: 27190191 DOI: 10.1093/infdis/jiw189] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/02/2016] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori is the strongest risk factor for gastric adenocarcinoma, which develops within a hypochlorhydric environment. We sequentially isolated H. pylori (strain J99) from a patient who developed corpus-predominant gastritis and hypochlorhydia over a 6-year interval. Archival J99 survived significantly better under acidic conditions than recent J99 strains. H. pylori arsRS encodes a 2-component system critical for stress responses; recent J99 isolates harbored 2 nonsynonymous arsS mutations, and arsS inactivation abolished acid survival. In vivo, acid-resistant archival, but not recent J99, successfully colonized high-acid-secreting rodents. Thus, genetic evolution of arsS may influence progression to hypochlorhydia and gastric cancer.
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Affiliation(s)
- Uma Krishna
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition
| | - Judith Romero-Gallo
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition
| | - Giovanni Suarez
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition
| | - Ayeetin Azah
- Meharry Medical College School of Medicine, Nashville, Tennessee
| | - Andrzej M Krezel
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, Missouri
| | - Matthew G Varga
- Department of Cancer Biology, Vanderbilt University School of Medicine
| | - Mark H Forsyth
- Department of Biology, The College of William and Mary, Williamsburg, Virginia
| | - Richard M Peek
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition Department of Cancer Biology, Vanderbilt University School of Medicine
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90
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Park HJ, Lee GH, Jun J, Son M, Kang MJ. Multiple-unit tablet of probiotic bacteria for improved storage stability, acid tolerability, and in vivo intestinal protective effect. Drug Des Devel Ther 2016; 10:1355-64. [PMID: 27103789 PMCID: PMC4827893 DOI: 10.2147/dddt.s103894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The aim of this study was to formulate probiotics-loaded pellets in a tablet form to improve storage stability, acid tolerability, and in vivo intestinal protective effect. Bacteria-loaded pellets primarily prepared with hydroxypropyl methylcellulose acetate succinate were compressed into tablets with highly compressible excipients and optimized for flow properties, hardness, and disintegration time. The optimized probiotic tablet consisted of enteric-coated pellets (335 mg), microcrystalline cellulose (Avicel PH102, 37.5 mg), and porous calcium silicate (25 mg) and allowed whole survival of living bacteria during the compaction process with sufficient tablet hardness (13 kp) and disintegration time (14 minutes). The multiple-unit tablet showed remarkably higher storage stability under ambient conditions (25°C/60% relative humidity) over 6 months and resistance to acidic medium compared to uncoated strains or pellets. Repeated intake of this multiple-unit tablet significantly lowered plasma level of endotoxin, a pathogenic material, compared to repeated intake of bare probiotics or marketed products in rats. These results, therefore, suggest that the multiple-unit tablet is advantageous to better bacterial viability and gain the beneficial effects on the gut flora, including the improvement of intestinal barrier function.
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Affiliation(s)
- Hee Jun Park
- Dong-A Pharmaceutical Co. Ltd., Yongin, Gyeonggi, Korea
| | - Ga Hyeon Lee
- Dong-A Pharmaceutical Co. Ltd., Yongin, Gyeonggi, Korea
| | - Joonho Jun
- Dong-A Pharmaceutical Co. Ltd., Yongin, Gyeonggi, Korea
| | - Miwon Son
- Dong-A Pharmaceutical Co. Ltd., Yongin, Gyeonggi, Korea
| | - Myung Joo Kang
- College of Pharmacy, Dankook University, Cheonan, Chungnam, Korea
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91
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Li XQ, Tang RC. Crosslinked and Dyed Chitosan Fiber Presenting Enhanced Acid Resistance and Bioactivities. Polymers (Basel) 2016; 8:E119. [PMID: 30979211 PMCID: PMC6432234 DOI: 10.3390/polym8040119] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 03/27/2016] [Accepted: 03/29/2016] [Indexed: 12/18/2022] Open
Abstract
The application of biodegradable chitosan fiber for healthy and hygienic textiles is limited due to its poor acid resistance in wet processing and poor antioxidant activity. In order to prepare chitosan fiber with good acid resistance and high antioxidant activity, chitosan fiber was first crosslinked by a water-soluble aziridine crosslinker, and then dyed with natural lac dye consisting of polyphenolic anthraquinone compounds. The main application conditions and crosslinking mechanism of the aziridine crosslinker, the adsorption mechanism and building-up property of lac dye on the crosslinked fiber, and the effects of crosslinking and dyeing on the antioxidant and antibacterial activities of chitosan fiber were studied. The crosslinked fiber exhibited greatly reduced weight loss in acidic solution, and possessed excellent acid resistance. Lac dye displayed a very high adsorption capability on the crosslinked fiber and a high utilization rate under weakly acidic medium. The Langmuir⁻Nernst isotherm was the best model to describe the adsorption behavior of lac dye, and Langmuir adsorption had great contribution to total adsorption. Lac dyeing imparted good antioxidant activity to chitosan fiber. Crosslinking and dyeing had no impact on the good inherent antibacterial activity of chitosan fiber.
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Affiliation(s)
- Xiao-Qiong Li
- College of Textile and Clothing Engineering, Soochow University, 199 Renai Road, Suzhou 215123, China.
| | - Ren-Cheng Tang
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, 199 Renai Road, Suzhou 215123, China.
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92
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Tillman GE, Simmons M, Wasilenko JL, Narang N, Cray WC, Bodeis-Jones S, Martin G, Gaines S, Seal BS. Development of a real-time PCR for Escherichia coli based on gadE, an acid response regulatory gene. Lett Appl Microbiol 2014; 60:196-202. [PMID: 25384850 DOI: 10.1111/lam.12359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/06/2014] [Accepted: 11/06/2014] [Indexed: 12/01/2022]
Abstract
Increasingly, molecular methods have become important in identification and confirmation of bacteria at the species level. Rapid molecular methods provide sensitivity and specificity while reducing cost and resources. The primary goal of this study was to develop a real-time PCR assay for identification of Escherichia coli from an agar plate. GadE (gadE) directly regulates the glutamate-dependent acid response system (GDAR) in E. coli and is responsible for survival of at pH 2. Based on gene sequence data, a real-time PCR assay targeting gadE was developed for this purpose. Seventy bacterial isolates recovered from ground beef enrichments and 714 isolates from caecal contents were identified biochemically and tested with the real-time PCR assay developed in this study. The PCR assay and the biochemical identification had 100% agreement on the tested isolates. The gadE real-time PCR assay was demonstrated in this study to be an inexpensive, reliable method for confirming E. coli colonies within 1.5 h from an agar plate, thereby saving on final identification time.
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Affiliation(s)
- G E Tillman
- United States Department of Agriculture, Food Safety and Inspection Service, Eastern Laboratory Outbreaks Section, Athens, GA, USA
| | - M Simmons
- United States Department of Agriculture, Food Safety and Inspection Service, Eastern Laboratory Outbreaks Section, Athens, GA, USA
| | - J L Wasilenko
- United States Department of Agriculture, Food Safety and Inspection Service, Eastern Laboratory Outbreaks Section, Athens, GA, USA
| | - N Narang
- United States Department of Agriculture, Food Safety and Inspection Service, Eastern Laboratory Outbreaks Section, Athens, GA, USA
| | - W C Cray
- United States Department of Agriculture, Food Safety and Inspection Service, Eastern Laboratory Outbreaks Section, Athens, GA, USA
| | - S Bodeis-Jones
- United States Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, MD, USA
| | - G Martin
- United States Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, MD, USA
| | - S Gaines
- United States Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, MD, USA
| | - B S Seal
- United States Department of Agriculture, Agricultural Research Service, Poultry Microbiological Safety Research Unit, Athens, GA, USA
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93
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Lee SH, Hong KN, Park JK, Ko J. Influence of Aggregate Coated with Modified Sulfur on the Properties of Cement Concrete. Materials (Basel) 2014; 7:4739-4754. [PMID: 28788703 PMCID: PMC5455898 DOI: 10.3390/ma7064739] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 06/10/2014] [Accepted: 06/10/2014] [Indexed: 11/16/2022]
Abstract
This paper proposes the mixing design of concrete having modified sulfur-coated aggregate (MSCA) to enhance the durability of Portland cement concrete. The mechanical properties and durability of the proposed MSCA concrete were evaluated experimentally. Melting-modified sulfur was mixed with aggregate in order to coat the aggregate surface at a speed of 20 rpm for 120 s. The MSCA with modified sulfur corresponding to 5% of the cement weight did not significantly affect the flexural strength in a prism concrete beam specimen, regardless of the water-cement ratio (W/C). However, a dosage of more than 7.5% decreased the flexural strength. On the other hand, the MSCA considerably improved the resistance to the sulfuric acid and the freezing-thawing, regardless of the sulfur dosage in the MSCA. The coating modified sulfur of 5% dosage consequently led to good results for the mechanical properties and durability of MSCA concrete.
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Affiliation(s)
- Swoo-Heon Lee
- Department of Civil Engineering, University of Texas at Arlington, Arlington, TX 76019, USA.
| | - Ki-Nam Hong
- School of Civil Engineering, Chungbuk National University, Chungbuk 361-763, Korea.
| | - Jae-Kyu Park
- School of Civil Engineering, Chungbuk National University, Chungbuk 361-763, Korea.
| | - Jung Ko
- Railway Inspection Section, Korea Infrastructure Safety & Technology Corporation, Gyeonggi 411-758, Korea.
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94
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Mitra A, Fay PA, Vendura KW, Alla Z, Carroll RK, Shaw LN, Riordan JT. σ(N) -dependent control of acid resistance and the locus of enterocyte effacement in enterohemorrhagic Escherichia coli is activated by acetyl phosphate in a manner requiring flagellar regulator FlhDC and the σ(S) antagonist FliZ. Microbiologyopen 2014; 3:497-512. [PMID: 24931910 PMCID: PMC4287178 DOI: 10.1002/mbo3.183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/30/2014] [Accepted: 05/15/2014] [Indexed: 12/02/2022] Open
Abstract
In enterohemorrhagic Escherichia coli (EHEC), sigma factor N (σN) regulates glutamate-dependent acid resistance (GDAR) and the locus of enterocyte effacement (LEE); discrete genetic systems that are required for transmission and virulence of this intestinal pathogen. Regulation of these systems requires nitrogen regulatory protein C, NtrC, and is a consequence of NtrC-σN-dependent reduction in the activity of sigma factor S (σS). This study elucidates pathway components and stimuli for σN-directed regulation of GDAR and the LEE in EHEC. Deletion of fliZ, the product of which reduces σS activity, phenocopied rpoN (σN) and ntrC null strains for GDAR and LEE control, acid resistance, and adherence. Upregulation of fliZ by NtrC-σN was shown to be indirect and required an intact flagellar regulator flhDC. Activation of flhDC by NtrC-σN and FlhDC-dependent regulation of GDAR and the LEE was dependent on σN-promoter flhDP2, and a newly described NtrC upstream activator sequence. Addition of ammonium chloride significantly altered expression of GDAR and LEE, acid resistance, and adherence, independently of rpoN, ntrC, and the NtrC sensor kinase, ntrB. Altering the availability of NtrC phosphodonor acetyl phosphate by growth without glucose, with acetate addition, or by deletion of acetate kinase ackA, abrogated NtrC-σN-dependent control of flhDC, fliZ, GDAR, and the LEE.
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Affiliation(s)
- Avishek Mitra
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, Florida, 33620
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95
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Abstract
Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for a variety of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, such as Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired yield and titer. In fact, their potency as microbial inhibitors is highlighted by the fact that many of these carboxylic acids are routinely used as food preservatives. This review highlights the current knowledge regarding the impact that saturated, straight-chain carboxylic acids, such as hexanoic, octanoic, decanoic, and lauric acids can have on E. coli and S. cerevisiae, with the goal of identifying metabolic engineering strategies to increase robustness. Key effects of these carboxylic acids include damage to the cell membrane and a decrease of the microbial internal pH. Certain changes in cell membrane properties, such as composition, fluidity, integrity, and hydrophobicity, and intracellular pH are often associated with increased tolerance. The availability of appropriate exporters, such as Pdr12, can also increase tolerance. The effect on metabolic processes, such as maintaining appropriate respiratory function, regulation of Lrp activity and inhibition of production of key metabolites such as methionine, are also considered. Understanding the mechanisms of biocatalyst inhibition by these desirable products can aid in the engineering of robust strains with improved industrial performance.
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Affiliation(s)
- Laura R Jarboe
- Department of Chemical and Biological Engineering, Iowa State University Ames, IA, USA ; Department of Microbiology, Iowa State University Ames, IA, USA
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96
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Deng Z, Shan Y, Pan Q, Gao X, Yan A. Anaerobic expression of the gadE-mdtEF multidrug efflux operon is primarily regulated by the two-component system ArcBA through antagonizing the H-NS mediated repression. Front Microbiol 2013; 4:194. [PMID: 23874328 PMCID: PMC3708157 DOI: 10.3389/fmicb.2013.00194] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 06/24/2013] [Indexed: 12/28/2022] Open
Abstract
The gadE-mdtEF operon encodes a central acid resistance regulator GadE and two multidrug efflux proteins MdtEF. Although transcriptional regulation of gadE in the context of acid resistance under the aerobic growth environment of Escherichia coli has been extensively studied, regulation of the operon under the physiologically relevant environment of anaerobic growth and its effect on the expression of the multidrug efflux proteins MdtEF in the operon has not been disclosed. Our previous study revealed that anaerobic induction of the operon was dependent on ArcA, the response regulator of the ArcBA two-component system, in the M9 glucose minimal medium. However, the detailed regulatory mechanism remains unknown. In this study, we showed that anaerobic activation of mdtEF was driven by the 798 bp unusually long gadE promoter. Deletion of evgA, ydeO, rpoS, and gadX which has been shown to activate the gadE expression during acid stresses under aerobic condition did not have a significant effect on the anaerobic activation of the operon. Rather, anaerobic activation of the operon was largely dependent on the global regulator ArcA and a GTPase MnmE. Under aerobic condition, transcription of gadE was repressed by the global DNA silencer H-NS in M9 minimal medium. Interestingly, under anaerobic condition, while ΔarcA almost completely abolished transcription of gadE-mdtEF, further deletion of hns in ΔarcA mutant restored the transcription of the full-length PgadE-lacZ, and P1- and P3-lacZ fusions, suggesting an antagonistic effect of ArcA on the H-NS mediated repression. Taken together, we conclude that the anaerobic activation of the gadE-mdtEF was primarily mediated by the two-component system ArcBA through antagonizing the H-NS mediated repression.
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Affiliation(s)
- Ziqing Deng
- School of Biological Sciences, The University of Hong Kong Hong Kong, China
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97
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Mathew A, Reddy NV, Sugumaran DK, Peter J, Shameer M, Dauravu LM. Acquired acid resistance of human enamel treated with laser (Er:YAG laser and Co2 laser) and acidulated phosphate fluoride treatment: An in vitro atomic emission spectrometry analysis. Contemp Clin Dent 2013; 4:170-5. [PMID: 24015004 PMCID: PMC3757877 DOI: 10.4103/0976-237x.114864] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND Dental caries is essentially a process of diffusion and dissolution. If the aspect of dissolution can be curtailed some degree of prevention can be achieved. AIMS The present study was carried out to evaluate and compare the effect of Er:YAG laser and Co2 laser irradiation combined with acidulated phosphate fluoride treatment on in vitro acid resistance of human enamel. DESIGN An in vitro study was carried out on 30 human premolars to evaluate the enamel's acid resistance using an atomic emission spectrometry analysis. MATERIALS AND METHODS A total of 60 enamel specimens were prepared from 30 human premolars and were randomly assigned to 6 groups: (1) Untreated (control); (2) 1.23% acidulated phosphate fluoride (APF) gel application alone for 4 min; (3) Er:YAG laser treatment alone; (4) Co2 laser treatment alone; (5) Er:YAG laser + APF gel application; (6) Co2 laser + APF gel application. The specimens were then individually immersed in 5 ml of acetate buffer solution (0.1 mol/L, pH 4.5) and incubated at 37°C for 24 h, and the acid resistance was evaluated by determining the calcium ion concentration using the atomic emission spectrometry. STATISTICAL ANALYSIS An ANOVA model was constructed (P value of 0.05), followed by Tukey's test for multiple pair wise comparisons of mean values. RESULTS Significant differences were found between the control group and the test groups (P < 0.001). CONCLUSIONS Combining acidulated phosphate fluoride with either Er:YAG or Co2 laser had a synergistic effect in decreasing the enamel demineralization more than either fluoride treatment or laser treatment alone.
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Affiliation(s)
- Anju Mathew
- Department of Paedodontics, Mar Baselious Dental College, Kothamangalam, Ernakulam, Kerala, India
| | - N. Venugopal Reddy
- Department of Paedodontics and Preventive Dentistry, Rajah Muthaih Dental College and Hospital, Annamalai University, Chidambaram, Tamil Nadu, India
| | - D. K. Sugumaran
- Department of Paedodontics and Preventive Dentistry, Rajah Muthaih Dental College and Hospital, Annamalai University, Chidambaram, Tamil Nadu, India
| | - Joby Peter
- Department of Paedodontics and Preventive Dentistry, Rajah Muthaih Dental College and Hospital, Annamalai University, Chidambaram, Tamil Nadu, India
| | - M. Shameer
- Department of Paedodontics and Preventive Dentistry, Rajah Muthaih Dental College and Hospital, Annamalai University, Chidambaram, Tamil Nadu, India
| | - Liju Marcely Dauravu
- Department of Orthodontics, Mar Baselious Dental College, Kothamangalam, Ernakulam, Kerala, India
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98
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Abstract
Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a human pathogen responsible for outbreaks of bloody diarrhea and hemolytic uremic syndrome (HUS) worldwide. Conventional antimicrobials trigger an SOS response in EHEC that promotes the release of the potent Shiga toxin that is responsible for much of the morbidity and mortality associated with EHEC infection. Cattle are a natural reservoir of EHEC, and approximately 75% of EHEC outbreaks are linked to the consumption of contaminated bovine-derived products. This review will discuss how EHEC causes disease in humans but is asymptomatic in adult ruminants. It will also analyze factors utilized by EHEC as it travels through the bovine gastrointestinal (GI) tract that allow for its survival through the acidic environment of the distal stomachs, and for its ultimate colonization in the recto-anal junction (RAJ). Understanding the factors crucial for EHEC survival and colonization in cattle will aid in the development of alternative strategies to prevent EHEC shedding into the environment and consequent human infection.
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Affiliation(s)
- Y Nguyen
- Department of Microbiology, The University of Texas Southwestern Medical Center Dallas, TX, USA
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99
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Le MT, Porcelli I, Weight CM, Gaskin DJH, Carding SR, van Vliet AHM. Acid-shock of Campylobacter jejuni induces flagellar gene expression and host cell invasion. Eur J Microbiol Immunol (Bp) 2012; 2:12-9. [PMID: 24611116 DOI: 10.1556/eujmi.2.2012.1.3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 01/14/2012] [Indexed: 11/19/2022] Open
Abstract
The bacterial pathogen Campylobacter jejuni is the leading cause of foodborne gastroenteritis in the developed world, with the organism being transmitted by ingestion of contaminated and undercooked poultry. Exposure to acid is an inevitable stressor for C. jejuni during gastric passage, yet the effect of low pH on C. jejuni virulence is still poorly understood. Here, we investigate the effect of acid-shock on C. jejuni viability, gene expression and host-cell invasion. C. jejuni strain NCTC 11168 survived acid exposure at pH 3.5 and above for up to 30 min without a drop in viability, and this exposure induced the expression of flagellar genes transcribed from σ(54)-dependent promoters. Furthermore, acid-shock resulted in increased C. jejuni invasion of m-ICcl2 mouse small intestine crypt cells grown on transwells, but not when the cells were grown on flat-bottomed wells. This suggests that C. jejuni might be invading intestinal epithelial cells at the basolateral side, possibly after paracellular passage. We hypothesize that acid-shock prior to intestinal entry may serve as a signal that primes C. jejuni to express its virulence gene repertoire including flagellar motility genes, but this requires further study in the context of an appropriate colonization or disease model.
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100
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Lee JS, Choe YH, Lee JH, Lee HJ, Lee JH, Choi YO. Helicobacter pylori urease activity is influenced by ferric uptake regulator. Yonsei Med J 2010; 51:39-44. [PMID: 20046512 PMCID: PMC2799959 DOI: 10.3349/ymj.2010.51.1.39] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 05/06/2009] [Accepted: 05/06/2009] [Indexed: 01/22/2023] Open
Abstract
PURPOSE The role of the Ferric Uptake Regulator (FUR) in the acid resistance of Helicobacter pylori (H. pylori) has been thought to be independent of urease. However, we demonstrated in this study that Fur influences urease activity. MATERIALS AND METHODS A fur knockout mutant of H. pylori was constructed by replacing the Fur gene with a kanamycin resistant marker gene. The wild-type H. pylori and fur mutant were compared for survival. The integrity of the inner membrane of the bacteria was evaluated by confocal microscopy using membrane-permeant and -impermeant fluorescent DNA probes. Urease activity of intact H. pylori was measured between pH 3 and 8. Real time PCR of both strains was performed for urease genes including ureI, ureE, ureF, ureG, and ureH. RESULTS The fur deletion affected the survival of H. pylori at pH 4. The urease activity curve of the intact fur mutant showed the same shape as the wild-type but was 3-fold lower than the wild-type at a pH of less than 5. Real time PCR revealed that the expression of all genes was consistently down-regulated in the fur mutant. CONCLUSION The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.
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Affiliation(s)
- Jong Seung Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yon Ho Choe
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji Hyuk Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hye Jin Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jee Hyun Lee
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Young Ok Choi
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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