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Freeman CD, Hansen T, Urbauer R, Wilkinson BJ, Singh VK, Hines KM. Defective pgsA contributes to increased membrane fluidity and cell wall thickening in Staphylococcus aureus with high-level daptomycin resistance. mSphere 2024:e0011524. [PMID: 38752757 DOI: 10.1128/msphere.00115-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 04/17/2024] [Indexed: 05/28/2024] Open
Abstract
Daptomycin is a membrane-targeting last-resort antimicrobial therapeutic for the treatment of infections caused by methicillin- and/or vancomycin-resistant Staphylococcus aureus. In the rare event of failed daptomycin therapy, the source of resistance is often attributable to mutations directly within the membrane phospholipid biosynthetic pathway of S. aureus or in the regulatory systems that control cell envelope response and membrane homeostasis. Here we describe the structural changes to the cell envelope in a daptomycin-resistant isolate of S. aureus strain N315 that has acquired mutations in the genes most commonly reported associated with daptomycin resistance: mprF, yycG, and pgsA. In addition to the decreased phosphatidylglycerol (PG) levels that are the hallmark of daptomycin resistance, the mutant with high-level daptomycin resistance had increased branched-chain fatty acids (BCFAs) in its membrane lipids, increased membrane fluidity, and increased cell wall thickness. However, the successful utilization of isotope-labeled straight-chain fatty acids (SCFAs) in lipid synthesis suggested that the aberrant BCFA:SCFA ratio arose from upstream alteration in fatty acid synthesis rather than a structural preference in PgsA. Transcriptomics studies revealed that expression of pyruvate dehydrogenase (pdhB) was suppressed in the daptomycin-resistant isolate, which is known to increase BCFA levels. While complementation with an additional copy of pdhB had no effect, complementation of the pgsA mutation resulted in increased PG formation, reduction in cell wall thickness, restoration of normal BCFA levels, and increased daptomycin susceptibility. Collectively, these results demonstrate that pgsA contributes to daptomycin resistance through its influence on membrane fluidity and cell wall thickness, in addition to phosphatidylglycerol levels. IMPORTANCE The cationic lipopeptide antimicrobial daptomycin has become an essential tool for combating infections with Staphylococcus aureus that display reduced susceptibility to β-lactams or vancomycin. Since daptomycin's activity is based on interaction with the negatively charged membrane of S. aureus, routes to daptomycin-resistance occur through mutations in the lipid biosynthetic pathway surrounding phosphatidylglycerols and the regulatory systems that control cell envelope homeostasis. Therefore, there are many avenues to achieve daptomycin resistance and several different, and sometimes contradictory, phenotypes of daptomycin-resistant S. aureus, including both increased and decreased cell wall thickness and membrane fluidity. This study is significant because it demonstrates the unexpected influence of a lipid biosynthesis gene, pgsA, on membrane fluidity and cell wall thickness in S. aureus with high-level daptomycin resistance.
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Affiliation(s)
| | - Tayte Hansen
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, USA
| | - Ramona Urbauer
- Department of Chemistry, University of Georgia, Athens, Georgia, USA
| | - Brian J Wilkinson
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Vineet K Singh
- Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, USA
| | - Kelly M Hines
- Department of Chemistry, University of Georgia, Athens, Georgia, USA
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Niño-Arias FC, Alves VF, Pereira MG, De Martinis ECP. Gene expression and cell culture assays reveal cheese isolate Lactococcus lactis MC5 may influence the virulence of Staphylococcus aureus. Braz J Microbiol 2023; 54:2027-2034. [PMID: 37171534 PMCID: PMC10484841 DOI: 10.1007/s42770-023-01004-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 04/29/2023] [Indexed: 05/13/2023] Open
Abstract
Staphylococcus aureus (SA) can thrive in a wide variety of hosts and environments, causing clinical infections and foodborne intoxications. In Brazil, SA is commonly isolated from traditional soft cheeses, especially those prepared from unpasteurized milk. In this research, the isolate S. aureus SABRC1 was evaluated for virulence traits under different conditions, including co-inoculation with Lactococcus lactis MC5 (isolated from "Fresh Minas Cheese"), which produces antibacterial peptides. Results from experiments with Caco-2 culture indicated S. aureus SABRC1 was able to adhere (42.83 ± 1.79%) and to invade (48.57 ± 0.41%) the intestinal cells. On the other hand, L. lactis MC5 presented anti-staphylococcal activity as indicated by agar assays, and it was also able to antagonize intestinal cell invasion by S. aureus. Moreover, Reverse Transcriptase-PCR experiments showed virulence genes of S. aureus SABRC1 (hla, icaA and sea) were differentially expressed under diverse culture conditions, which included Brain Heart Infusion modified or not by the addition of glucose, sodium chloride, milk or cheese. This suggests the virulence of S. aureus SABRC1 is influenced by compounds commonly found in daily diets, and not only by its genetic repertoire, adding a novel level of complexity for controlling infection by this pathogen.
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Affiliation(s)
- Fabian Camilo Niño-Arias
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (FCFRP-USP), Brazil
| | - Virgínia Farias Alves
- Faculdade de Farmácia, Universidade Federal de Goiás, Rua 240 Esquina Com a 5ª Avenida, S/N, Setor Leste Universitário, Goiânia/GO, CEP: 74605-170, Brazil.
| | - Marita Gimenez Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (FCFRP-USP), Brazil
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Bian N, Chen X, Ren X, Yu Z, Jin M, Chen X, Liu C, Luan Y, Wei L, Chen Y, Song W, Zhao Y, Wang B, Jiang T, Zhang C, Shu Z, Su X, Wang L. 7,8-Dihydroxyflavone attenuates the virulence of Staphylococcus aureus by inhibiting alpha-hemolysin. World J Microbiol Biotechnol 2022; 38:200. [PMID: 35995893 DOI: 10.1007/s11274-022-03378-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 08/05/2022] [Indexed: 11/29/2022]
Abstract
Staphylococcus aureus (S. aureus), a Gram-positive bacteria, is an incurable cause of hospital and community-acquired infections. Inhibition bacterial virulence is a viable strategy against S. aureus infections based on the multiple virulence factors secreted by S. aureus. Alpha-hemolysin (Hla) plays a crucial role in bacteria virulence without affecting bacterial viability. Here, we identified that 7,8-Dihydroxyflavone (7,8-DHF), a natural compound, was able to decrease the expression of and did not affect the in vitro growth of S. aureus USA300 at a concentration of 32 μg/mL. It was verified by western blot and RT-qPCR that the natural compound could inhibit the transcription and translation of Hla. Further mechanism studies revealed that 7,8-DHF has a negative effect on transcriptional regulator agrA and RNAIII, preventing the upregulation of virulence gene. Cytotoxicity assays showed that 7,8-DHF did not produce significant cytotoxicity to A549 cells. Animal experiments showed that the combination of 7,8-DHF and vancomycin had a more significant therapeutic effect on S. aureus infection, reflecting the synergistic effect of 7,8-DHF with antibiotics. In conclusion, 7,8-DHF was able to target Hla to protect host cells from hemolysis while limiting the development of bacterial resistance.
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Affiliation(s)
- Nan Bian
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Xiangqian Chen
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Xinran Ren
- School of Pharmaceutical Science, Jilin University, Changchun, 130021, China
| | - Zishu Yu
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Mengli Jin
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Xiaoyu Chen
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Chang Liu
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Yanhe Luan
- The First Affiliated Hospital to Changchun University of Chinese Medicine, Changchun, 130021, China
| | - Lin Wei
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Ying Chen
- The First Affiliated Hospital to Changchun University of Chinese Medicine, Changchun, 130021, China
| | - Wu Song
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Yicheng Zhao
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Bingmei Wang
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Tao Jiang
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Chi Zhang
- Changchun University of Chinese Medicine, Changchun, 130117, China
| | - Zunhua Shu
- The Third Affiliated Hospital to Changchun University of Chinese Medicine, Changchun, 130118, China.
| | - Xin Su
- Changchun University of Chinese Medicine, Changchun, 130117, China.
| | - Li Wang
- Changchun University of Chinese Medicine, Changchun, 130117, China.
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Biofilm and Gene Expression Characteristics of the Carbapenem-Resistant Enterobacterales, Escherichia coli IMP, and Klebsiella pneumoniae NDM-1 Associated with Common Bacterial Infections. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19084788. [PMID: 35457654 PMCID: PMC9024719 DOI: 10.3390/ijerph19084788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 04/12/2022] [Accepted: 04/12/2022] [Indexed: 01/16/2023]
Abstract
In light of the limited therapeutic options with Carbapenem-Resistant Enterobacterales (CRE) infections, understanding the bacterial risk factors, such as biofilm formation and related gene expression of CRE, is vital. This study investigates the biofilm formation and biofilm-related gene expression of two enteric Enterobacterales with major CR determinants Escherichia coli IMP and Klebsiella pneumoniae NDM-1, which were seen in high prevalence in most common bacterial infections over the past few years. To our knowledge, this is the first study that demonstrated the relationship between biofilm formation and the related gene expression, to understand the potential molecular mechanisms during the biofilm formation in CRE. Biofilms were quantified by tissue culture plate assay at the stages of the biofilm development: initial attachment (6 h), microcolony formation (12 h), maturation (24 h), and dispersion (48 h). In a dispersion, event bacteria detach without any mechanical means and colonise another area. To investigate the influence of different growth conditions on biofilm formation, biofilms were quantified under different growth conditions. In parallel, quantitative real-time PCR (qPCR) assessed the biofilm-related gene expression of a cluster of genes, including biofilm maturation, quorum sensing, stress survival, and antibiotic resistance. Structural changes during biofilm development were assessed via confocal laser scanning microscopy (CLSM). We observed that the biofilm formation of CRE is correlated with the biofilm development stages, with maximum biofilm observed at 24 h at the maturation stage. Our data also showed that biofilm growth, under the condition tested, is the major factor influencing the variability of biofilm gene expression quantification assays. qPCR analyses have demonstrated that the expression of biofilm-related genes is highly correlated with phenotypic biofilm development, and these findings can be further expanded to understand the variation in regulation of such genes in these significant CRE pathogens. Our study demonstrated that both CRE strains, E. coli IMP and K. pneumoniae NDM-1, are high biofilm formers, and genes involved in biofilm development are upregulated during biofilm growth. The characteristic of the increased biofilm formation with the upregulation of antibiotic-resistant and biofilm-related genes indicates the successful pathogenic role of biofilms of these selected CRE and is attributed to their multi-drug resistance ability and successful dissemination of CRE in common bacterial infections.
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Expression of Staphylococcal Virulence Genes In Situ in Human Skin and Soft Tissue Infections. Antibiotics (Basel) 2022; 11:antibiotics11040527. [PMID: 35453277 PMCID: PMC9032627 DOI: 10.3390/antibiotics11040527] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 11/16/2022] Open
Abstract
Background: Staphylococcus aureus, the most common pathogen in skin and soft tissue infections (SSTI), harbors many well-characterized virulence genes. However, the expression of many of them in SSTIs is unknown. In this study, S. aureus virulence genes expressed in SSTI were investigated. Methods: Fifty-three subjects presenting to the outpatient’s care and emergency departments with a purulent SSTI at two medical centers in Wisconsin, USA, were enrolled in the study. Total mRNA was extracted from the purulent or swab materials, made into cDNA and sequenced on MiSeq platform. The relative cDNA counts to gmk and identifications of the transcripts were carried out with respect to USA300 reference genome and using SAMTOOLS v.1.3 and BWA, respectively. Result: A significantly higher cDNA count was observed for many of the virulence and regulatory gene transcripts in the pus samples compared to the swab samples relative to the cDNA counts for gmk, a housekeeping gene. They were for lukS-PV (18.6 vs. 14.2), isaA (13.4 vs. 8.5), ssaA (4.8 vs. 3.1), hlgC (1.4 vs. 1.33), atl (17.7 vs. 8.33), clfA (3.9 vs. 0.83), eno (6.04 vs. 3.16), fnbA (5.93 vs. 0.33), saeS (6.3 vs. 1.33), saeR (5.4 vs. 3.33) and agrC (5.6 vs. 1.5). Conclusions: A relative increase in the transcripts of several toxins, adhesion and regulatory genes with respect to a gmk in purulent materials suggests their role in situ during SSTIs, perhaps in an orchestrated manner.
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The effects of antidepressants fluoxetine, sertraline, and amitriptyline on the development of antibiotic resistance in Acinetobacter baumannii. Arch Microbiol 2022; 204:230. [PMID: 35355118 DOI: 10.1007/s00203-022-02853-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/14/2022] [Accepted: 03/14/2022] [Indexed: 11/02/2022]
Abstract
This study investigates the effects of antidepressants fluoxetine, sertraline, and amitriptyline on the development of antibiotic resistance in clinical Acinetobacter baumannii isolates. The isolates were exposed to fluoxetine, sertraline, and amitriptyline for 30 days, respectively. The bacteria that developed resistance to gentamicin, imipenem, colistin, and ciprofloxacin were isolated and expression levels of some antibiotic-resistance genes were determined by quantitative reverse-transcriptase PCR. Before and after the exposure, minimum inhibitory concentration (MIC) values of the bacteria were determined by the microdilution method. The statistical analysis was performed using Student's t test. A time-dependent increase was observed in the number of bacteria that developed resistance and increased the MIC value. After exposure to fluoxetine and sertraline, decreases were observed for efflux and outer membrane porin genes in isolates that developed colistin resistance, and increases were observed in isolates that developed ciprofloxacin resistance. These observations suggest that these antidepressants have similar effects on the development of resistance. While the exposure to fluoxetine did not result in the development of resistance to imipenem, it was observed after exposure to sertraline and amitriptyline, and a common decrease in ompA gene expression was determined in these isolates. To our knowledge, the comparative effects of selected antidepressants on the development of antibiotic resistance in A. baumannii are reported and presented in the literature here for the first time.
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Mahdally NH, George RF, Kashef MT, Al-Ghobashy M, Murad FE, Attia AS. Staquorsin: A Novel Staphylococcus aureus Agr-Mediated Quorum Sensing Inhibitor Impairing Virulence in vivo Without Notable Resistance Development. Front Microbiol 2021; 12:700494. [PMID: 34290689 PMCID: PMC8287904 DOI: 10.3389/fmicb.2021.700494] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/11/2021] [Indexed: 12/11/2022] Open
Abstract
The emergence of microbial resistance to the available antibiotics is a major public health concern, especially with the limited rate of developing new antibiotics. The utilization of anti-virulence agents is a non-conventional approach that can be used to combat microbial infection. In Staphylococcus aureus, many virulence factors are regulated by the Agr-mediated quorum sensing (QS). We developed a chemical compound that acts a potential Agr-inhibitor without reducing bacterial viability. The compound was designated staquorsin for Staphylococcus aureus QS inhibitor. In silico analyses confirmed the binding of staquorsin to the AgrA active site with an absolute binding score comparable to savirin, a previously described AgrA inhibitor. However, staquorsin turned out to be superior over savarin in not affecting the S. aureus viability in concentrations up to 600 μM. On the other hand, savirin inhibited S. aureus growth in concentrations as low as 25 μM. Moreover, staquorsin proved to be a potent inhibitor of the Agr system by inhibiting hemolysins, lipase production, and affecting biofilms formation and detachment. On the molecular level it significantly inhibited the effector transcript RNA III. In vivo testing, using the murine skin abscess model, confirmed the ability of staquorsin to modulate S. aureus virulence by effectively controlling the infection. Twenty passages of S. aureus in the presence of 40 μM staquorsin have not resulted in loss of activity as evidenced by maintaining its ability to reduce hemolysin production and RNA III transcript levels. In conclusion, we hereby describe a novel anti-virulence compound inhibiting the S. aureus Agr-system and its associated virulence factors. It is active both in vitro and in vivo, and its frequent use does not lead to the development of resistance. These findings model staquorsin as a promising drug candidate to join the fierce battle against the formidable pathogen S. aureus.
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Affiliation(s)
- Norhan H Mahdally
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Riham F George
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Mona T Kashef
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Medhat Al-Ghobashy
- Department of Analytical Chemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt.,School of Pharmacy, Newgiza University, Giza, Egypt
| | - Fathia E Murad
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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The Role of Subinhibitory Concentrations of Daptomycin and Tigecycline in Modulating Virulence in Staphylococcus aureus. Antibiotics (Basel) 2021; 10:antibiotics10010039. [PMID: 33401579 PMCID: PMC7823975 DOI: 10.3390/antibiotics10010039] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/06/2020] [Accepted: 12/17/2020] [Indexed: 11/28/2022] Open
Abstract
Staphylococcus aureus (S. aureus) infections are notoriously complicated by the ability of the organism to grow in biofilms and are difficult to eradicate with antimicrobial therapy. The purpose of the current study was to clarify the influence of sub-inhibitory concentrations (sub-MICs) of daptomycin and tigecycline antibiotics on biofilm adhesion factors and exoproteins expressions by S. aureus clinical isolates. Six clinical isolates representing positive biofilm S. aureus clones (3 methicillin-sensitive S. aureus (MSSA) and 3 methicillin-resistant S. aureus (MRSA)) were grown with sub-MICs (0.5 MIC) of two antibiotics (daptomycin and tigecycline) for 12 h of incubation. RNA extracted from culture pellets was used via relative quantitative real-time-PCR (qRT-PCR) to determine expression of specific adhesion (fnbA, fnbB, clfA, clfB, fib, ebps, cna, eno) and biofilm (icaADBC) genes. To examine the effect of sub-MIC of these antibiotics on the expression of extracellular proteins, samples from the culture supernatants of six isolates were collected after 12 h of treatment with or without tigecycline in order to profile protein production via 2D gel sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D gel-SDS-PAGE). Sub-MIC treatment of all clinical MRSA and MSSA strains with daptomycin or tigecycline dramatically induced or suppressed fnbA, fnbB, clfA, clfB, fib, ebps, cna, eno, and icaADBC gene expression. Furthermore, sub-MIC use of tigecycline significantly reduced the total number of separated protein spots across all the isolates, as well as decreasing production of certain individual proteins. Collectively, this study showed very different responses in terms of both gene expression and protein secretion across the various isolates. In addition, our results suggest that sub-MIC usage of daptomycin and tigecycline could signal virulence induction by S. aureus via the regulation of biofilm adhesion factor genes and exoproteins. If translating findings to the clinical treatment of S. aureus, the therapeutic regimen should be adapted depending on antibiotic, the virulence factor and strain type.
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Chu AJ, Qiu Y, Harper R, Lin L, Ma C, Yang X. Nusbiarylins Inhibit Transcription and Target Virulence Factors in Bacterial Pathogen Staphylococcus aureus. Int J Mol Sci 2020; 21:ijms21165772. [PMID: 32796751 PMCID: PMC7461214 DOI: 10.3390/ijms21165772] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/02/2020] [Accepted: 08/07/2020] [Indexed: 12/29/2022] Open
Abstract
The emergence of multidrug resistance in the clinically significant pathogen Staphylococcus aureus is a global health burden, compounded by a diminishing drug development pipeline, and a lack of approved novel antimicrobials. Our previously reported first-in-class bacterial transcription inhibitors “nusbiarylins” presented a promising prospect towards the discovery of novel antimicrobial agents with a novel mechanism. Here we investigated and characterised the lead nusbiarylin compound, MC4, and several of its chemical derivatives in both methicillin-resistant S. aureus (MRSA) and the S. aureus type strains, demonstrating their capacity for the arrest of growth and cellular respiration, impairment of RNA and intracellular protein levels at subinhibitory concentrations. In some instances, derivatives of MC4 were also shown to attenuate the production of staphylococcal virulence factors in vitro, such as the exoproteins α-toxin and Panton–Valentine Leukocidin (PVL). Trends observed from quantitative PCR assays suggested that nusbiarylins elicited these effects possibly by acting via but not limited to the modulation of global regulatory pathways, such as the agr regulon, which coordinates the expression of S. aureus genes associated with virulence. Our findings encourage the continued development of more potent compounds within this novel family of bacterial transcription inhibitors.
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Affiliation(s)
- Adrian Jun Chu
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
| | - Yangyi Qiu
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong;
| | - Rachel Harper
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
| | - Lin Lin
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
| | - Cong Ma
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong;
- Correspondence: (C.M.); (X.Y.)
| | - Xiao Yang
- Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; (A.J.C.); (R.H.); (L.L.)
- Correspondence: (C.M.); (X.Y.)
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Khemici V, Prados J, Petrignani B, Di Nolfi B, Bergé E, Manzano C, Giraud C, Linder P. The DEAD-box RNA helicase CshA is required for fatty acid homeostasis in Staphylococcus aureus. PLoS Genet 2020; 16:e1008779. [PMID: 32730248 PMCID: PMC7392221 DOI: 10.1371/journal.pgen.1008779] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/15/2020] [Indexed: 01/05/2023] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen that can grow in a wide array of conditions: on abiotic surfaces, on the skin, in the nose, in planktonic or biofilm forms and can cause many type of infections. Consequently, S. aureus must be able to adapt rapidly to these changing growth conditions, an ability largely driven at the posttranscriptional level. RNA helicases of the DEAD-box family play an important part in this process. In particular, CshA, which is part of the degradosome, is required for the rapid turnover of certain mRNAs and its deletion results in cold-sensitivity. To understand the molecular basis of this phenotype, we conducted a large genetic screen isolating 82 independent suppressors of cold growth. Full genome sequencing revealed the fatty acid synthesis pathway affected in many suppressor strains. Consistent with that result, sublethal doses of triclosan, a FASII inhibitor, can partially restore growth of a cshA mutant in the cold. Overexpression of the genes involved in branched-chain fatty acid synthesis was also able to suppress the cold-sensitivity. Using gas chromatography analysis of fatty acids, we observed an imbalance of straight and branched-chain fatty acids in the cshA mutant, compared to the wild-type. This imbalance is compensated in the suppressor strains. Thus, we reveal for the first time that the cold sensitive growth phenotype of a DEAD-box mutant can be explained, at least partially, by an improper membrane composition. The defect correlates with an accumulation of the pyruvate dehydrogenase complex mRNA, which is inefficiently degraded in absence of CshA. We propose that the resulting accumulation of acetyl-CoA fuels straight-chained fatty acid production at the expense of the branched ones. Strikingly, addition of acetate into the medium mimics the cshA deletion phenotype, resulting in cold sensitivity suppressed by the mutations found in our genetic screen or by sublethal doses of triclosan. DEAD-box RNA helicases are highly conserved proteins found in all domains of life. By acting on RNA secondary structures they determine the fate of RNA from transcription to degradation. Bacterial DEAD-box RNA helicases are not essential under laboratory conditions but are required for fitness and under stress conditions. Whereas many DEAD-box protein mutants display a cold sensitive phenotype, the underlying mechanisms have been studied only in few cases and found to be associated with ribosome biogenesis. We aimed here to elucidate the cold sensitivity of a cshA mutant in the Gram-positive opportunist pathogen Staphylococcus aureus. Our study revealed for the first time that part of the cold sensitivity is related to the inability of the bacterium to adapt the cytoplasmic membrane to lower temperatures. We propose that straight-chain fatty acid synthesis, reduced to sustain growth at lower temperature, is maintained due to inefficient turn-over of the pyruvate dehydrogenase mRNA, leading to elevated acetyl-CoA levels. This study allowed us to unravel at least in part the cold sensitive phenotype and to show that the pyruvate dehydrogenase activity plays an important function in the regulation of fatty acid composition of the membrane, a process that remains poorly understood in Gram-positive bacteria.
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Affiliation(s)
- Vanessa Khemici
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Julien Prados
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Bianca Petrignani
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Benjamin Di Nolfi
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Elodie Bergé
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Caroline Manzano
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Caroline Giraud
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Linder
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- * E-mail:
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Wu Y, Liu Y, Dong K, Li Q. Effects of human β-defensin 3 fused with carbohydrate-binding domain on the function of type III secretion system in Pseudomonas aeruginosa PA14. Braz J Microbiol 2020; 51:29-35. [PMID: 31933178 DOI: 10.1007/s42770-020-00223-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 01/07/2020] [Indexed: 02/06/2023] Open
Abstract
Antimicrobial peptides are considered to be one of the candidate antimicrobial agents for antibiotic-resistant bacterial infection in the future. The effects of antimicrobial peptide hBD3-CBD on Pseudomonas aeruginosa PA14 and PA14 ΔexsA were analyzed by the bactericidal effects, hemolysis assays, pyocyanin pigment productions, and virulence factor expressions (exoU, exoS, hcnA, and lasB). Pyocyanin production and virulence factor expressions are important features of the type III secretion system in Pseudomonas aeruginosa. HBD3-CBD killed PA14 and PA14 ΔexsA with similar efficiency; it lowered the hemolysis levels of PA14 and PA14 ΔexsA and reduced the pyocyanin production, biofilm formation, and exoU, exoS, and lasB expressions in PA14. Compared with PA14, PA14 ΔexsA showed a lower hemolysis effect, pyocyanin production, exoU, and lasB expressions. The effects of hBD3-CBD on the PA14 toxin secretion were similar to the changes in the type III secretion system mutant isolate PA14 ΔexsA. Our results demonstrated that the type III secretion system was involved in the biological functions on PA 14 from hBD3-CBD.
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Affiliation(s)
- Yunqiang Wu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, B06, Building 1, 280 South Chongqing Road, Shanghai, 200025, China.,Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yanan Liu
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, B06, Building 1, 280 South Chongqing Road, Shanghai, 200025, China
| | - Ke Dong
- Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Qingtian Li
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, B06, Building 1, 280 South Chongqing Road, Shanghai, 200025, China.
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12
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Huang P, Shao X, Zhu M, Xu B, Chen C, Li P. Sucrose enhances colour formation in dry sausages by up-regulating gene expression of nitric oxide synthase in Staphylococcus vitulinus. Int J Food Microbiol 2019; 315:108419. [PMID: 31734616 DOI: 10.1016/j.ijfoodmicro.2019.108419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/30/2019] [Accepted: 11/02/2019] [Indexed: 12/20/2022]
Abstract
The effects of glucose and sucrose on the gene expression of nitric oxide synthase (NOS) in Staphylococcus vitulinus and colour formation in dry sausages were investigated. The results showed that sucrose addition promoted nitric oxide (NO) production in media when compared with glucose. In addition, sucrose could up-regulate nos (encoding NOS) and katA (encoding catalase KatA) gene expression by enhancing oxidative stress levels. In the sausages inoculated with S. vitulinus, a*-values (indicating redness) of the sausages with added sucrose were higher than those of samples with added glucose (P < 0.05) but did not differ from those in the nitrite treatment group (P > 0.05). The UV-vis spectra results showed that nitrosylmyoglobin (NO-Mb) was formed in the sausages with either S. vitulinus or nitrite added. In the S. vitulinus-inoculated sausages, sucrose addition led to a higher NO-Mb content than that after glucose addition, which was attributed to up-regulation of the nos gene. This study provides a potential method to enhance NO yield in S. vitulinus and colour formation in dry sausages without nitrite addition.
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Affiliation(s)
- Pan Huang
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei 230009, China; School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Xuefei Shao
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei 230009, China; School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Miaomiao Zhu
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei 230009, China; School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Baocai Xu
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei 230009, China; School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Conggui Chen
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei 230009, China; School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Peijun Li
- Engineering Research Center of Bio-process, Ministry of Education, Hefei University of Technology, Hefei 230009, China; School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China.
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Metabolite Cross-Feeding between Rhodococcus ruber YYL and Bacillus cereus MLY1 in the Biodegradation of Tetrahydrofuran under pH Stress. Appl Environ Microbiol 2019; 85:AEM.01196-19. [PMID: 31375492 DOI: 10.1128/aem.01196-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 07/23/2019] [Indexed: 11/20/2022] Open
Abstract
Bacterial consortia are among the most basic units in the biodegradation of environmental pollutants. Pollutant-degrading strains frequently encounter different types of environmental stresses and must be able to survive with other bacteria present in the polluted environments. In this study, we proposed a noncontact interaction mode between a tetrahydrofuran (THF)-degrading strain, Rhodococcus ruber YYL, and a non-THF-degrading strain, Bacillus cereus MLY1. The metabolic interaction mechanism between strains YYL and MLY1 was explored through physiological and molecular studies and was further supported by the metabolic response profile of strain YYL, both monocultured and cocultured with strain MLY1 at the optimal pH (pH 8.3) and under pH stress (pH 7.0), through a liquid chromatography-mass spectrometry-based metabolomic analysis. The results suggested that the coculture system resists pH stress in three ways: (i) strain MLY1 utilized acid metabolites and impacted the proportion of glutamine, resulting in an elevated intracellular pH of the system; (ii) strain MLY1 had the ability to degrade intermediates, thus alleviating the product inhibition of strain YYL; and (iii) strain MLY1 produced some essential micronutrients for strain YYL to aid the growth of this strain under pH stress, while strain YYL produced THF degradation intermediates for strain MLY1 as major nutrients. In addition, a metabolite cross-feeding interaction with respect to pollutant biodegradation is discussed.IMPORTANCE Rhodococcus species have been discovered in diverse environmental niches and can degrade numerous recalcitrant toxic pollutants. However, the pollutant degradation efficiency of these strains is severely reduced due to the complexity of environmental conditions and limitations in the growth of the pollutant-degrading microorganism. In our study, Bacillus cereus strain MLY1 exhibited strong stress resistance to adapt to various environments and improved the THF degradation efficiency of Rhodococcus ruber YYL by a metabolic cross-feeding interaction style to relieve the pH stress. These findings suggest that metabolite cross-feeding occurred in a complementary manner, allowing a pollutant-degrading strain to collaborate with a nondegrading strain in the biodegradation of various recalcitrant compounds. The study of metabolic exchanges is crucial to elucidate mechanisms by which degrading and symbiotic bacteria interact to survive environmental stress.
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Hajiahmadi F, Alikhani MY, Shariatifar H, Arabestani MR, Ahmadvand D. The bactericidal effect of lysostaphin coupled with liposomal vancomycin as a dual combating system applied directly on methicillin-resistant Staphylococcus aureus infected skin wounds in mice. Int J Nanomedicine 2019; 14:5943-5955. [PMID: 31447553 PMCID: PMC6683660 DOI: 10.2147/ijn.s214521] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 06/28/2019] [Indexed: 11/23/2022] Open
Abstract
Background and aim Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of surgical infection, and its resistance to numerous conventional antibiotics makes treatment difficult. Although vancomycin is often an effective agent for the initial therapy of MRSA, clinical failure sometimes occurs. Therefore, there is an urgent need to develop better therapies. Here, we prepared some vancomycin-loaded nanoliposomes coupled with anti-staphylococcal protein (lysostaphin) and evaluated their in vitro and in vivo efficacy as a topical MRSA therapy. Methods Vancomycin was encapsulated in liposomes, and the coupling of lysostaphin with the surface of liposomes was carried out through cyanuric functional groups. The bactericidal efficacies and a full characterization were evaluated. To define different nanoliposomal–bacterium interactions and their bactericidal effect, flow cytometry was employed. Finally, in vivo, the topical antibacterial activity of each formulation was measured against surgical wound MRSA infection in a mouse model. Results High encapsulation and conjugation efficiency were achieved for all formulations. All the formulations showed a significant reduction in bacterial counts (p<0.05). The targeted liposomes more effectively suppress bacterial infection in vitro and in vivo relative to equivalent doses of untargeted vancomycin liposome. The flow cytometry results confirmed liposome–bacterium interactions, which increased during the incubation time. The maximum binding rate and the bactericidal effect were significantly higher in targeted liposomes (p<0.05) compared with control liposomes. Conclusion Our data suggest a novel nano-vehicle (lysostaphin-conjugated coupled liposomal vancomycin) which could be used as a great topical antimicrobial construct for treatment of MRSA skin infections.
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Affiliation(s)
- Fahimeh Hajiahmadi
- Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Yousef Alikhani
- Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran.,Brucellosis Research Center, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Hanifeh Shariatifar
- Young Researches and Elite Club, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Mohammad Reza Arabestani
- Department of Microbiology, Hamadan University of Medical Sciences, Hamadan, Iran.,Brucellosis Research Center, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Davoud Ahmadvand
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.,Department of Medical Laboratory Sciences, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran
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Singh VK, Sirobhushanam S, Ring RP, Singh S, Gatto C, Wilkinson BJ. Roles of pyruvate dehydrogenase and branched-chain α-keto acid dehydrogenase in branched-chain membrane fatty acid levels and associated functions in Staphylococcus aureus. J Med Microbiol 2018; 67:570-578. [PMID: 29498620 DOI: 10.1099/jmm.0.000707] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Membrane fluidity to a large extent is governed by the presence of branched-chain fatty acids (BCFAs). Branched-chain α-keto acid dehydrogenase (BKD) is the key enzyme in BCFA synthesis. A Staphylococcus aureus BKD-deficient strain still produced substantial levels of BCFAs. Pyruvate dehydrogenase (PDH) with structural similarity to BKD has been speculated to contribute to BCFAs in S. aureus. METHODOLOGY This study was carried out using BKD-, PDH- and BKD : PDH-deficient derivatives of methicillin-resistant S. aureus strain JE2. Differences in growth kinetics were evaluated spectrophotometrically, membrane BCFAs using gas chromatography and membrane fluidity by fluorescence polarization. Carotenoid levels were estimated by measuring A465 of methanol extracts from 48 h cultures. MIC values were determined by broth microdilution.Results/Key findings. BCFAs made up 50 % of membrane fatty acids in wild-type but only 31 % in the BKD-deficient mutant. BCFA level was ~80 % in the PDH-deficient strain and 38 % in the BKD : PDH-deficient strain. BKD-deficient mutant showed decreased membrane fluidity, the PDH-deficient mutant showed increased membrane fluidity. The BKD- and PDH-deficient strains grew slower and the BKD : PDH-deficient strain grew slowest at 37 °C. However at 20 °C, the BKD- and BKD : PDH-deficient strains grew only a little followed by autolysis of these cells. The BKD-deficient strain produced higher levels of staphyloxanthin. The PDH-deficient and BKD : PDH-deficient strains produced very little staphyloxanthin. The BKD-deficient strain showed increased susceptibility to daptomycin. CONCLUSION The BCFA composition of the cell membrane in S. aureus seems to significantly impact cell growth, membrane fluidity and resistance to daptomycin.
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Affiliation(s)
- Vineet K Singh
- Microbiology & Immunology, A.T. Still University of Health Sciences, Kirksville, MO 63501, USA
| | - Sirisha Sirobhushanam
- Microbiology Group, School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Robert P Ring
- Microbiology & Immunology, A.T. Still University of Health Sciences, Kirksville, MO 63501, USA
| | - Saumya Singh
- Microbiology & Immunology, A.T. Still University of Health Sciences, Kirksville, MO 63501, USA
| | - Craig Gatto
- Microbiology Group, School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Brian J Wilkinson
- Microbiology Group, School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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Djalma Chaves R, Pradella F, Turatti MA, Amaro EC, da Silva AR, dos Santos Farias A, Pereira JL, Mousavi Khaneghah A. Evaluation of Staphylococcus spp. in food and kitchen premises of Campinas, Brazil. Food Control 2018. [DOI: 10.1016/j.foodcont.2017.09.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Engineering chimeric two-component system into Escherichia coli from Paracoccus denitrificans to sense methanol. BIOTECHNOL BIOPROC E 2017. [DOI: 10.1007/s12257-016-0484-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Lima-E-Silva AA, Silva-Filho RG, Fernandes HMZ, Saramago CSM, Viana AS, Souza MJ, Nogueira EM. Sub-Inhibitory Concentrations of Rifampicin Strongly Stimulated Biofilm Production in S. aureus. Open Microbiol J 2017; 11:142-151. [PMID: 28839494 PMCID: PMC5543614 DOI: 10.2174/1874285801711010142] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 04/25/2017] [Accepted: 04/25/2017] [Indexed: 11/22/2022] Open
Abstract
Background and Objectives: Staphylococcus aureus is an important pathogen and a frequent cause of infections associated with biofilm production in implantable medical devices. Biofilm production can be induced by sub-inhibitory concentrations (sub-MICs) of certain antibiotics, but few studies have researched this occurrence in S. aureus. In this study, we investigated the effect of sub-MICs of rifampicin and minocycline on biofilm production by five clinical and five non-clinical S. aureus isolates. Methods: Microtiter Plate assay and Congo Red Agar Test were used to analyze the biofilm production. The biofilm composition was evaluated by the detachment assay with sodium metaperiodate and proteinase K. Results: Rifampicin sub-MICs induced very high biofilm formation in seven isolates that were non-producers in Tryptic Soy Broth. In one producer isolate, the biofilm formation level was not affected by sub-MICs of this drug. Sub-MICs of minocycline did not induce biofilm production in all isolates tested and in two producer isolates, instead, MIC/2 and MIC/4 inhibited biofilm production. The results of the drugs in combination were similar to those with rifampicin alone. The biofilm matrix was identified as polysaccharide, except for one producer isolate, classified as proteinaceous. Polysaccharide biofilm producer isolates, when grown on Congo Red Agar without sucrose, but with sub-MICs of rifampicin, showed results in agreement with those obtained in Microtiter Plate Test. Conclusion: The high biofilm production induced by sub-MICs of rifampicin has potential clinical relevance, because this is one of the drugs commonly used in the impregnation of catheters. In addition, it is used adjunctively to treat certain S. aureus infections.
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Affiliation(s)
- Agostinho Alves Lima-E-Silva
- Department of Microbiology and Parasitology Rio de Janeiro, Biomedical Institute, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Renato Geraldo Silva-Filho
- Department of Microbiology and Parasitology Rio de Janeiro, Biomedical Institute, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | | | - Carmen Soares Meirelles Saramago
- Department of Microbiology and Parasitology Rio de Janeiro, Biomedical Institute, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Alice Slotfeldt Viana
- Department of Microbiology and Parasitology Rio de Janeiro, Biomedical Institute, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | | | - Eduardo Matos Nogueira
- Laboratory of Genomic, Biomedical Institute, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
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Selvamani V, Maruthamuthu MK, Arulsamy K, Eom GT, Hong SH. Construction of methanol sensing Escherichia coli by the introduction of novel chimeric MxcQZ/OmpR two-component system from Methylobacterium organophilum XX. KOREAN J CHEM ENG 2017. [DOI: 10.1007/s11814-017-0063-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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20
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The antifungal caspofungin increases fluoroquinolone activity against Staphylococcus aureus biofilms by inhibiting N-acetylglucosamine transferase. Nat Commun 2016; 7:13286. [PMID: 27808087 PMCID: PMC5097165 DOI: 10.1038/ncomms13286] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 09/20/2016] [Indexed: 01/04/2023] Open
Abstract
Biofilms play a major role in Staphylococcus aureus pathogenicity but respond poorly to antibiotics. Here, we show that the antifungal caspofungin improves the activity of fluoroquinolones (moxifloxacin, delafloxacin) against S. aureus biofilms grown in vitro (96-well plates or catheters) and in vivo (murine model of implanted catheters). The degree of synergy among different clinical isolates is inversely proportional to the expression level of ica operon, the products of which synthesize poly-N-acetyl-glucosamine polymers, a major constituent of biofilm matrix. In vitro, caspofungin inhibits the activity of IcaA, which shares homology with β-1-3-glucan synthase (caspofungin's pharmacological target in fungi). This inhibition destructures the matrix, reduces the concentration and polymerization of exopolysaccharides in biofilms, and increases fluoroquinolone penetration inside biofilms. Our study identifies a bacterial target for caspofungin and indicates that IcaA inhibitors could potentially be useful in the treatment of biofilm-related infections. Biofilms formed by Staphylococcus aureus are poorly responsive to antibiotics. Here, Siala et al. show that an antifungal drug (caspofungin) enhances the activity of fluoroquinolone antibiotics against S. aureus biofilms by inhibiting an enzyme involved in synthesis of the biofilm matrix.
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Jomehpour N, Eslami G, Khalili MB. The Effect of Ferula assa-foetida L and Carum copticum Hydroalcoholic Extract on the Expression Levels of Staphylococcus aureus Genes Involved in Quorum Sensing. Jundishapur J Microbiol 2016; 9:e33879. [PMID: 27942357 PMCID: PMC5136442 DOI: 10.5812/jjm.33879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 08/16/2016] [Accepted: 08/29/2016] [Indexed: 12/26/2022] Open
Abstract
Background Quorum sensing is a microbial cell-to-cell communication process. Quorum sensing bacteria produce and release extracellular messenger molecules called autoinducers. Gram-positive and Gram-negative, homoserine lactones, and oligopeptides are autoinducers used to communicate and regulate gene expression. Objectives The goal of this study was to assess the impact of subinhibitory concentrations of Ferula assa-foetida l oleo-gum resin and Carum copticum fruit on the expression of tst and hld genes of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains. Methods This analytical study was performed using standard strains of MRSA (ATCC 33591) and MSSA (ATCC 29213). Suspensions of MRSA and MSSA bacteria were incubated at 37°C for 7 and 16 hours in the presence of ethanol extracts from F. assa-foetida and C. copticum. The expression of the hld and tst genes was then assessed using the real-time PCR protocol and SYBR Green Master Mix. The data analysis was carried out using the 2-ΔΔCT method. Results The hld gene expression (RNAIII) of MRSA after 7 and 16 hours of exposure to the sMIC of the F. assa-foetida extract showed a fold change of -1 and 0.08, respectively, in comparison with controls. After 7 and 16 hours of exposure to the sMIC of the C. copticum extract, the fold change was -0.23 and -0.27, respectively. After exposure to the sMIC of the C. copticum extract for 16 hours, the fold change in the expression of the tst (TSST-1) MSSA gene was 0.37 lower than that of the control sample. Conclusions The results indicate that sMICs of ethanol extracts from F. assa-foetida and C. copticum can be used to control the expression of virulence genes in pathogenic bacteria, such as MRSA and MSSA.
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Affiliation(s)
- Najmeh Jomehpour
- Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
| | - Gilda Eslami
- Research Center for Food Hygiene and Safety, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
- Department of Parasitology and Mycology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
- Corresponding author: Gilda Eslami, Department of Parasitology and Mycology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran. Tel/Fax: +98-3538203411, E-mail:
| | - Mohammad Bagher Khalili
- Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, IR Iran
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Ganesh I, Maruthamuthu MK, Hong SH. Engineering a chimeric malate two-component system by introducing a positive feedback loop in Escherichia coli. KOREAN J CHEM ENG 2016. [DOI: 10.1007/s11814-015-0209-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Modification of the dynamic nature of the chimeric fumarate two-component system in Escherichia coli via positive feedback loop. BIOTECHNOL BIOPROC E 2015. [DOI: 10.1007/s12257-015-0255-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Regulation of Expression of Oxacillin-Inducible Methionine Sulfoxide Reductases in Staphylococcus aureus. Int J Microbiol 2015; 2015:617925. [PMID: 26483841 PMCID: PMC4592908 DOI: 10.1155/2015/617925] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 08/26/2015] [Accepted: 09/02/2015] [Indexed: 11/29/2022] Open
Abstract
Cell wall-active antibiotics cause induction of a locus that leads to elevated synthesis of two methionine sulfoxide reductases (MsrA1 and MsrB) in Staphylococcus aureus. To understand the regulation of this locus, reporter strains were constructed by integrating a DNA fragment consisting of the msrA1/msrB promoter in front of a promoterless lacZ gene in the chromosome of wild-type and MsrA1-, MsrB-, MsrA1/MsrB-, and SigB-deficient methicillin-sensitive S. aureus strain SH1000 and methicillin-resistant S. aureus strain COL. These reporter strains were cultured in TSB and the cellular levels of β-galactosidase activity in these cultures were assayed during different growth phases. β-galactosidase activity assays demonstrated that the lack of MsrA1, MsrB, and SigB upregulated the msrA1/msrB promoter in S. aureus strain SH1000. In S. aureus strain COL, the highest level of β-galactosidase activity was observed under the conditions when both MsrA1 and MsrB proteins were absent. The data suggest that the msrA1/msrB locus, in part, is negatively regulated by MsrA1, MsrB, and SigB in S. aureus.
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Cusick KD, Fitzgerald LA, Cockrell AL, Biffinger JC. Selection and Evaluation of Reference Genes for Reverse Transcription-Quantitative PCR Expression Studies in a Thermophilic Bacterium Grown under Different Culture Conditions. PLoS One 2015; 10:e0131015. [PMID: 26115538 PMCID: PMC4482720 DOI: 10.1371/journal.pone.0131015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/26/2015] [Indexed: 11/18/2022] Open
Abstract
The phylum Deinococcus-Thermus is a deeply-branching lineage of bacteria widely recognized as one of the most extremophilic. Members of the Thermus genus are of major interest due to both their bioremediation and biotechnology potentials. However, the molecular mechanisms associated with these key metabolic pathways remain unknown. Reverse-transcription quantitative PCR (RT-qPCR) is a high-throughput means of studying the expression of a large suite of genes over time and under different conditions. The selection of a stably-expressed reference gene is critical when using relative quantification methods, as target gene expression is normalized to expression of the reference gene. However, little information exists as to reference gene selection in extremophiles. This study evaluated 11 candidate reference genes for use with the thermophile Thermus scotoductus when grown under different culture conditions. Based on the combined stability values from BestKeeper and NormFinder software packages, the following are the most appropriate reference genes when comparing: (1) aerobic and anaerobic growth: TSC_c19900, polA2, gyrA, gyrB; (2) anaerobic growth with varied electron acceptors: TSC_c19900, infA, pfk, gyrA, gyrB; (3) aerobic growth with different heating methods: gyrA, gap, gyrB; (4) all conditions mentioned above: gap, gyrA, gyrB. The commonly-employed rpoC does not serve as a reliable reference gene in thermophiles, due to its expression instability across all culture conditions tested here. As extremophiles exhibit a tendency for polyploidy, absolute quantification was employed to determine the ratio of transcript to gene copy number in a subset of the genes. A strong negative correlation was found to exist between ratio and threshold cycle (CT) values, demonstrating that CT changes reflect transcript copy number, and not gene copy number, fluctuations. Even with the potential for polyploidy in extremophiles, the results obtained via absolute quantification indicate that relative quantification is appropriate for RT-qPCR studies with this thermophile.
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Affiliation(s)
- Kathleen D Cusick
- National Research Council Associateship, US Naval Research Laboratory, 4555 Overlook Ave., SW, Washington DC, 20375, United States of America
| | - Lisa A Fitzgerald
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Ave., SW, Washington DC, 20375, United States of America
| | - Allison L Cockrell
- National Research Council Associateship, US Naval Research Laboratory, 4555 Overlook Ave., SW, Washington DC, 20375, United States of America
| | - Justin C Biffinger
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Ave., SW, Washington DC, 20375, United States of America
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Engineering Escherichia coli to sense acidic amino acids by introduction of a chimeric two-component system. KOREAN J CHEM ENG 2015. [DOI: 10.1007/s11814-015-0024-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Analysis of the effects of cigarette smoke on staphylococcal virulence phenotypes. Infect Immun 2015; 83:2443-52. [PMID: 25824841 DOI: 10.1128/iai.00303-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 03/24/2015] [Indexed: 11/20/2022] Open
Abstract
Cigarette smoking is the leading preventable cause of death, disease, and disability worldwide. It is well established that cigarette smoke provokes inflammatory activation and impairs antimicrobial functions of human immune cells. Here we explore whether cigarette smoke likewise affects the virulence properties of an important human pathogen, Staphylococcus aureus, and in particular methicillin-resistant S. aureus (MRSA), one of the leading causes of invasive bacterial infections. MRSA colonizes the nasopharynx and is thus exposed to inhalants, including cigarette smoke. MRSA exposed to cigarette smoke extract (CSE-MRSA) was more resistant to macrophage killing (4-fold higher survival; P < 0.0001). CSE-MRSA demonstrated reduced susceptibility to cell lysis (1.78-fold; P = 0.032) and antimicrobial peptide (AMP) (LL-37) killing (MIC, 8 μM versus 4 μM). CSE modified the surface charge of MRSA in a dose-dependent fashion, impairing the binding of particles with charge similar to that of AMPs by 90% (P < 0.0001). These changes persisted for 24 h postexposure, suggesting heritable modifications. CSE exposure increased hydrophobicity by 55% (P < 0.0001), which complemented findings of increased MRSA adherence and invasion of epithelial cells. CSE induced upregulation of mprF, consistent with increased MRSA AMP resistance. S. aureus without mprF had no change in surface charge upon exposure to CSE. In vivo, CSE-MRSA pneumonia induced higher mouse mortality (40% versus 10%) and increased bacterial burden at 8 and 20 h postinfection compared to control MRSA-infected mice (P < 0.01). We conclude that cigarette smoke-induced immune resistance phenotypes in MRSA may be an additional factor contributing to susceptibility to infectious disease in cigarette smokers.
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Evaluation of zraP gene expression characteristics and construction of a lead (Pb) sensing and removal system in a recombinant Escherichia coli. Biotechnol Lett 2014; 37:659-64. [PMID: 25433463 DOI: 10.1007/s10529-014-1732-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/05/2014] [Indexed: 10/24/2022]
Abstract
A ZraP-based lead sensing and removal system was constructed in E. coli. It was regulated by the ZraS/ZraR two-component system. The expression profile of the zraP gene towards extracellular lead was studied via real-time PCR. A dual-function bacterial system was also designed to express GFP and OmpC-lead binding peptide under the control of zraP for the simultaneous sensing and adsorption of environmental lead without additional manipulation. The constructed bacterial system can emit fluorescence and it adsorbed a maximum of 487 µmol lead/g cell DCW. From a study of artificial wastewater, the constructed bacteria adsorbed lead highly selectively (427 µmol lead/g cell DCW) among other metal ions. The newly-constructed dual function bacterial system can be applied for the development of an efficient process for the removal of lead from polluted wastes.
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Ganesh I, Ravikumar S, Yoo IK, Hong SH. Construction of malate-sensing Escherichia coli by introduction of a novel chimeric two-component system. Bioprocess Biosyst Eng 2014; 38:797-804. [DOI: 10.1007/s00449-014-1321-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 10/30/2014] [Indexed: 11/29/2022]
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Matthijs S, Vander Wauven C, Cornu B, Ye L, Cornelis P, Thomas CM, Ongena M. Antimicrobial properties of Pseudomonas strains producing the antibiotic mupirocin. Res Microbiol 2014; 165:695-704. [PMID: 25303834 DOI: 10.1016/j.resmic.2014.09.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 09/17/2014] [Accepted: 09/29/2014] [Indexed: 11/19/2022]
Abstract
Mupirocin is a polyketide antibiotic with broad antibacterial activity. It was isolated and characterized about 40 years ago from Pseudomonas fluorescens NCIMB 10586. To study the phylogenetic distribution of mupirocin producing strains in the genus Pseudomonas a large collection of Pseudomonas strains of worldwide origin, consisting of 117 Pseudomonas type strains and 461 strains isolated from different biological origins, was screened by PCR for the mmpD gene of the mupirocin gene cluster. Five mmpD(+) strains from different geographic and biological origin were identified. They all produced mupirocin and were strongly antagonistic against Staphylococcus aureus. Phylogenetic analysis showed that mupirocin production is limited to a single species. Inactivation of mupirocin production leads to complete loss of in vitro antagonism against S. aureus, except on certain iron-reduced media where the siderophore pyoverdine is responsible for the in vitro antagonism of a mupirocin-negative mutant. In addition to mupirocin some of the strains produced lipopeptides of the massetolide group. These lipopeptides do not play a role in the observed in vitro antagonism of the mupirocin producing strains against S. aureus.
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Affiliation(s)
- Sandra Matthijs
- Institut de Recherches Microbiologiques - Wiame, Campus du CERIA, 1 avenue Emile Gryson, bât 4B, B-1070 Bruxelles, Belgium.
| | - Corinne Vander Wauven
- Institut de Recherches Microbiologiques - Wiame, Campus du CERIA, 1 avenue Emile Gryson, bât 4B, B-1070 Bruxelles, Belgium.
| | - Bertrand Cornu
- Institut de Recherches Microbiologiques - Wiame, Campus du CERIA, 1 avenue Emile Gryson, bât 4B, B-1070 Bruxelles, Belgium.
| | - Lumeng Ye
- Department of Bioengineering Sciences, Research Group of Microbiology and Vlaams Instituut voor Biotechnologie, Vrije Universiteit Brussel, Brussels, Belgium.
| | - Pierre Cornelis
- Department of Bioengineering Sciences, Research Group of Microbiology and Vlaams Instituut voor Biotechnologie, Vrije Universiteit Brussel, Brussels, Belgium.
| | - Christopher M Thomas
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Marc Ongena
- Walloon Center for Industrial Biology, University of Liège, Gembloux Agro-Bio Tech, Gembloux, Belgium.
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Fusco V, Quero GM. Culture-Dependent and Culture-Independent Nucleic-Acid-Based Methods Used in the Microbial Safety Assessment of Milk and Dairy Products. Compr Rev Food Sci Food Saf 2014; 13:493-537. [DOI: 10.1111/1541-4337.12074] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/08/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Vincenzina Fusco
- Nal. Research Council of Italy; Inst. of Sciences of Food Production (CNR-ISPA); Bari Italy
| | - Grazia Marina Quero
- Nal. Research Council of Italy; Inst. of Sciences of Food Production (CNR-ISPA); Bari Italy
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Sihto HM, Tasara T, Stephan R, Johler S. Validation of reference genes for normalization of qPCR mRNA expression levels in Staphylococcus aureus exposed to osmotic and lactic acid stress conditions encountered during food production and preservation. FEMS Microbiol Lett 2014; 356:134-40. [PMID: 24893820 DOI: 10.1111/1574-6968.12491] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 05/30/2014] [Indexed: 12/01/2022] Open
Abstract
Staphylococcus aureus represents the most prevalent cause of food-borne intoxications worldwide. While being repressed by competing bacteria in most matrices, this pathogen exhibits crucial competitive advantages during growth at high salt concentrations or low pH, conditions frequently encountered in food production and preservation. We aimed to identify reference genes that could be used to normalize qPCR mRNA expression levels during growth of S. aureus in food-related osmotic (NaCl) and acidic (lactic acid) stress adaptation models. Expression stability of nine housekeeping genes was evaluated in full (LB) and nutrient-deficient (CYGP w/o glucose) medium under conditions of osmotic (4.5% NaCl) and acidic stress (lactic acid, pH 6.0) after 2-h exposure. Among the set of candidate reference genes investigated, rplD, rpoB,gyrB, and rho were most stably expressed in LB and thus represent the most suitable reference genes for normalization of qPCR data in osmotic or lactic acid stress models in a rich medium. Under nutrient-deficient conditions, expression of rho and rpoB was highly stable across all tested conditions. The presented comprehensive data on changes in expression of various S. aureus housekeeping genes under conditions of osmotic and lactic acid stress facilitate selection of reference genes for qPCR-based stress response models.
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Affiliation(s)
- Henna-Maria Sihto
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
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Chang YM, Ho CH, Chen CKM, Maestre-Reyna M, Chang-Chien MW, Wang AHJ. TcaR-ssDNA complex crystal structure reveals new DNA binding mechanism of the MarR family proteins. Nucleic Acids Res 2014; 42:5314-21. [PMID: 24531929 PMCID: PMC4005659 DOI: 10.1093/nar/gku128] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The teicoplanin-associated locus regulator (TcaR) regulates gene expression of proteins on the intercellular adhesion (ica) locus involved in staphylococci poly-N-acetylglucosamine biosynthesis. The absence of TcaR increases poly-N-acetylglucosamine production and promotes biofilm formation. Until recently, the mechanism of multiple antibiotic resistance regulator family protein members, such as TcaR, was restricted to binding double-stranded DNA. However, we recently found that TcaR strongly interacts with single-stranded DNA, which is a new role for this family of proteins. In this study, we report Staphylococcus epidermidis TcaR–single-stranded DNA complex structures. Our model suggests that TcaR and single-stranded DNA form a 61-symmetry polymer composed of TcaR dimers with single-stranded DNA that wraps outside the polymer and 12 nt per TcaR dimer. Single-stranded DNA binding to TcaR involves a large conformational change at the DNA binding lobe. Several point mutations involving the single-stranded DNA binding surface validate interactions between single-stranded DNA and TcaR. Our results extend the novel role of multiple antibiotic resistance regulator family proteins in staphylococci.
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Affiliation(s)
- Yu-Ming Chang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 11529, Taiwan and Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Chun-Han Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 11529, Taiwan and Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Cammy K.-M. Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 11529, Taiwan and Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Manuel Maestre-Reyna
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 11529, Taiwan and Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Masatoshi Weiting Chang-Chien
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 11529, Taiwan and Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Andrew H.-J. Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan, Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 11529, Taiwan and Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
- *To whom correspondence should be addressed. Tel +886 2 2788 1981; Fax +886 2 2788 2043;
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Synergism of glycoside hydrolase secretomes from two thermophilic bacteria cocultivated on lignocellulose. Appl Environ Microbiol 2014; 80:2592-601. [PMID: 24532065 DOI: 10.1128/aem.00295-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two cellulolytic thermophilic bacterial strains, CS-3-2 and CS-4-4, were isolated from decayed cornstalk by the addition of growth-supporting factors to the medium. According to 16S rRNA gene-sequencing results, these strains belonged to the genus Clostridium and showed 98.87% and 98.86% identity with Clostridium stercorarium subsp. leptospartum ATCC 35414(T) and Clostridium cellulosi AS 1.1777(T), respectively. The endoglucanase and exoglucanase activities of strain CS-4-4 were approximately 3 to 5 times those of strain CS-3-2, whereas the β-glucosidase activity of strain CS-3-2 was 18 times higher than that of strain CS-4-4. The xylanase activity of strain CS-3-2 was 9 times that of strain CS-4-4, whereas the β-xylosidase activity of strain CS-4-4 was 27 times that of strain CS-3-2. The enzyme activities in spent cultures following cocultivation of the two strains with cornstalk as the substrate were much greater than those in pure cultures or an artificial mixture of samples, indicating synergism of glycoside hydrolase secretomes between the two strains. Quantitative measurement of the two strains in the cocultivation system indicated that strain CS-3-2 grew robustly during the initial stages, whereas strain CS-4-4 dominated the system in the late-exponential phase. Liquid chromatography-tandem mass spectrometry analysis of protein bands appearing in the native zymograms showed that ORF3880 and ORF3883 from strain CS-4-4 played key roles in the lignocellulose degradation process. Both these open reading frames (ORFs) exhibited endoglucanase and xylanase activities, but ORF3880 showed tighter adhesion to insoluble substrates at 4, 25, and 60°C owing to its five carbohydrate-binding modules (CBMs).
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Ganesh I, Ravikumar S, Lee SH, Park SJ, Hong SH. Engineered fumarate sensing Escherichia coli based on novel chimeric two-component system. J Biotechnol 2013; 168:560-6. [DOI: 10.1016/j.jbiotec.2013.09.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/11/2013] [Indexed: 11/29/2022]
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Reference Gene Selection in Carnobacterium maltaromaticum, Lactobacillus curvatus, and Listeria innocua Subjected to Temperature and Salt Stress. Mol Biotechnol 2013; 56:210-22. [DOI: 10.1007/s12033-013-9697-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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37
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Shin K, Yun Y, Yi S, Lee HG, Cho JC, Suh KD, Lee J, Park J. Biofilm-forming ability of Staphylococcus aureus strains isolated from human skin. J Dermatol Sci 2013; 71:130-7. [DOI: 10.1016/j.jdermsci.2013.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 02/15/2013] [Accepted: 04/10/2013] [Indexed: 12/23/2022]
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The Role of theqacAGene in Mediating Resistance to Quaternary Ammonium Compounds. Microb Drug Resist 2013; 19:160-7. [DOI: 10.1089/mdr.2012.0154] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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39
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Zhong CY, Cheng AC, Wang MS, Zhu DK, Luo QH, Chen S, Zhang SH, Chen XY. Quantitative real-time PCR study of the expression and regulation of the tetracycline resistance gene inRiemerella anatipestifer. Poult Sci 2013; 92:1552-9. [DOI: 10.3382/ps.2012-02672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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40
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Expression characteristics of the maeA and maeB genes by extracellular malate and pyruvate in Escherichia coli. KOREAN J CHEM ENG 2013. [DOI: 10.1007/s11814-013-0061-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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Atshan SS, Shamsudin MN, Karunanidhi A, van Belkum A, Lung LTT, Sekawi Z, Nathan JJ, Ling KH, Seng JSC, Ali AM, Abduljaleel SA, Hamat RA. Quantitative PCR analysis of genes expressed during biofilm development of methicillin resistant Staphylococcus aureus (MRSA). INFECTION GENETICS AND EVOLUTION 2013; 18:106-12. [PMID: 23669446 DOI: 10.1016/j.meegid.2013.05.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/30/2013] [Accepted: 05/02/2013] [Indexed: 01/05/2023]
Abstract
Staphylococcus aureus biofilm associated infections remains a major clinical concern in patients with indwelling devices. Quantitative real-time PCR (qPCR) can be used to investigate the pathogenic role of such biofilms. We describe qPCRs for 12 adhesion and biofilm-related genes of four S. aureus isolates which were applied during in vitro biofilm development. An endogenous control (16S rRNA) was used for signal normalization. We compared the qPCR results with structural analysis using scanning electron microscopy (SEM). The SEM studies showed different cellular products surrounding the aggregated cells at different times of biofilm formation. Using qPCR, we found that expression levels of the gene encoding fibronectin binding protein A and B and clumping factor B (fnbA/B and clfB), which involves in primary adherence of S. aureus, were significantly increased at 24h and decreased slightly and variably at 48 h when all 4 isolates were considered. The elastin binding protein (ebps) RNA expression level was significantly enhanced more than 6-fold at 24 and 48 h compared to 12h. Similar results were obtained for the intercellular adhesion biofilm required genes type C (icaC). In addition, qPCR revealed a fluctuation in expression levels at different time points of biofilm growth of other genes, indicating that different parameter modes of growth processes are operating at different times.
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Affiliation(s)
- Salman Sahab Atshan
- Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
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AhrC and Eep are biofilm infection-associated virulence factors in Enterococcus faecalis. Infect Immun 2013; 81:1696-708. [PMID: 23460519 DOI: 10.1128/iai.01210-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Enterococcus faecalis is part of the human intestinal microbiome and is a prominent cause of health care-associated infections. The pathogenesis of many E. faecalis infections, including endocarditis and catheter-associated urinary tract infection (CAUTI), is related to the ability of clinical isolates to form biofilms. To identify chromosomal genetic determinants responsible for E. faecalis biofilm-mediated infection, we used a rabbit model of endocarditis to test strains with transposon insertions or in-frame deletions in biofilm-associated loci: ahrC, argR, atlA, opuBC, pyrC, recN, and sepF. Only the ahrC mutant was significantly attenuated in endocarditis. We demonstrate that the transcriptional regulator AhrC and the protease Eep, which we showed previously to be an endocarditis virulence factor, are also required for full virulence in murine CAUTI. Therefore, AhrC and Eep can be classified as enterococcal biofilm-associated virulence factors. Loss of ahrC caused defects in early attachment and accumulation of biofilm biomass. Characterization of ahrC transcription revealed that the temporal expression of this locus observed in wild-type cells promotes initiation of early biofilm formation and the establishment of endocarditis. This is the first report of AhrC serving as a virulence factor in any bacterial species.
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Qi J, Du Y, Bai H, Zhu X, Hu M, Luo Y, Liu Y. Global Protein Expression Profile Response ofEscherichia coliATCC 25922 Exposed to Enrofloxacin. Microb Drug Resist 2013; 19:6-14. [DOI: 10.1089/mdr.2012.0097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jing Qi
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Yijun Du
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Hua Bai
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Xiaoling Zhu
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Ming Hu
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Yanbo Luo
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Yuqing Liu
- Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China
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Low levels of β-lactam antibiotics induce extracellular DNA release and biofilm formation in Staphylococcus aureus. mBio 2012; 3:e00198-12. [PMID: 22851659 PMCID: PMC3419523 DOI: 10.1128/mbio.00198-12] [Citation(s) in RCA: 200] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Subminimal inhibitory concentrations of antibiotics have been shown to induce bacterial biofilm formation. Few studies have investigated antibiotic-induced biofilm formation in Staphylococcus aureus, an important human pathogen. Our goal was to measure S. aureus biofilm formation in the presence of low levels of β-lactam antibiotics. Fifteen phylogenetically diverse methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains were employed. Methicillin, ampicillin, amoxicillin, and cloxacillin were added to cultures at concentrations ranging from 0× to 1× MIC. Biofilm formation was measured in 96-well microtiter plates using a crystal violet binding assay. Autoaggregation was measured using a visual test tube settling assay. Extracellular DNA was quantitated using agarose gel electrophoresis. All four antibiotics induced biofilm formation in some strains. The amount of biofilm induction was as high as 10-fold and was inversely proportional to the amount of biofilm produced by the strain in the absence of antibiotics. MRSA strains of lineages USA300, USA400, and USA500 exhibited the highest levels of methicillin-induced biofilm induction. Biofilm formation induced by low-level methicillin was inhibited by DNase. Low-level methicillin also induced DNase-sensitive autoaggregation and extracellular DNA release. The biofilm induction phenotype was absent in a strain deficient in autolysin (atl). Our findings demonstrate that subminimal inhibitory concentrations of β-lactam antibiotics significantly induce autolysin-dependent extracellular DNA release and biofilm formation in some strains of S. aureus. The widespread use of antibiotics as growth promoters in agriculture may expose bacteria to low levels of the drugs. The aim of this study was to investigate the effects of low levels of antibiotics on bacterial autoaggregation and biofilm formation, two processes that have been shown to foster genetic exchange and antibiotic resistance. We found that low levels of β-lactam antibiotics, a class commonly used in both clinical and agricultural settings, caused significant autoaggregation and biofilm formation by the important human pathogen Staphylococcus aureus. Both processes were dependent on cell lysis and release of DNA into the environment. The effect was most pronounced among multidrug-resistant strains known as methicillin-resistant S. aureus (MRSA). These results may shed light on the recalcitrance of some bacterial infections to antibiotic treatment in clinical settings and the evolution of antibiotic-resistant bacteria in agricultural settings.
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An insight into the significance of the DnaK heat shock system in Staphylococcus aureus. Int J Med Microbiol 2012; 302:242-52. [PMID: 22748508 DOI: 10.1016/j.ijmm.2012.05.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 05/07/2012] [Accepted: 05/08/2012] [Indexed: 11/22/2022] Open
Abstract
The bacterium Staphylococcus aureus utilizes a variety of different mechanisms to survive unfavorable stress conditions that are critical for its persistence in the environment and for pathogenicity. The staphylococcal DnaK heat shock system functions as a major protein folding machine under stress conditions that cause aggregation and un-folding of proteins. In prior studies, S. aureus cells with a non-functional DnaK system showed reduced tolerance to heat, oxidative and antibiotic stresses, a lowered carotenoid production, and decreased survival in a murine host. This study provides insights that the altered phenotypes of the dnaK mutant cells are not due to decreased SigB activity in the mutant cell. Transcriptomic profiling studies provide evidence that a large number of genes encoding proteins involved in cell wall biogenesis, virulence and general stress tolerance, and genes encoding proteins involved in metabolic processes are differentially regulated in dnaK mutant cells relative to wild-type S. aureus. It was also determined that loss of functional DnaK caused a reduction in the ability of S. aureus to make biofilms and its adherence to eukaryotic cells. This study provides evidence of a global significance of DnaK heat shock system in S. aureus.
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Hu Y, Xie Y, Tang J, Shi X. Comparative expression analysis of two thermostable nuclease genes in Staphylococcus aureus. Foodborne Pathog Dis 2012; 9:265-71. [PMID: 22380879 DOI: 10.1089/fpd.2011.1033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Thermonuclease is known as a specific virulence factor in Staphylococcus aureus. It is widely used as a genetic marker for detection of S. aureus in various types of food. Previous studies have revealed the existence of two functional thermostable nucleases encoded by two different genes (nuc1 and nuc2) in S. aureus. To identify the expression characteristics of these two genes, comparative mRNA analysis of nuc1 and nuc2 was carried out by quantitative real-time polymerase chain reaction (PCR). Distinct expression patterns were observed at different growth stages, and expression was under the control of the sae regulatory system in strain RN4220. The maximum level of nuc1 transcripts was at the post-exponential growth phase, and expression was notably down-regulated in a sae mutant. In contrast, nuc2 transcript levels declined after the early exponential phase, and they were slightly up-regulated in the sae mutant. Furthermore, unlike the expression of nuc1, which varied in three different S. aureus clinical strains, the transcription of nuc2 remained relatively constant. The nuc1 transcription level correlated well with thermonuclease activity results, which suggests that nuc1 plays a primary role in thermonuclease activity in S. aureus. This information will be useful for understanding thermonuclease gene function and alterations of regulation for pathogenesis and diagnosis of S. aureus.
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Affiliation(s)
- Yu Hu
- MOST-USDA Joint Research Center for Food Safety and Bor Luh Food Safety Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
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Fajardo C, Ortíz LT, Rodríguez-Membibre ML, Nande M, Lobo MC, Martin M. Assessing the impact of zero-valent iron (ZVI) nanotechnology on soil microbial structure and functionality: a molecular approach. CHEMOSPHERE 2012; 86:802-8. [PMID: 22169206 DOI: 10.1016/j.chemosphere.2011.11.041] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/07/2011] [Accepted: 11/07/2011] [Indexed: 05/20/2023]
Abstract
In this work, nanoscale zero-valent iron (NZVI) particles have been used as an immobilisation strategy to reduce Pb and Zn availability and mobility in polluted soils. The application of NZVI to two soil microcosms (MPb and MZn) at a dose of 34 mg g(-1) soil efficiently immobilised Pb (25%) and zinc (20%). Exposure to NZVI had little impact on the microbial cellular viability and biological activity in the soils. Three bacterial genes (narG, nirS and gyrA) were used as treatment-related biomarkers. These biomarkers ruled out a broad bactericidal effect on the bulk soil microbial community. A transcriptome analysis of the genes did not reveal any changes in their expression ratios after the NZVI treatment: 1.6 (narG), 0.8 (nirS) and 0.7 (gyrA) in the MPb microcosm and 0.6 (narG), 1.2 (nirS) and 0.5 (gyrA) in the MZn microcosm. However, significant changes in the structure and composition of the soil bacteria population were detected by fluorescence in situ hybridisation. Thus, our results showed that NZVI toxicity could be highly dose and species dependent, and the effective applicability of the proposed molecular approach in assessing the impact of this immobilisation strategy on soil microbial population.
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Affiliation(s)
- C Fajardo
- Universidad Complutense de Madrid, Avenida Puerta de Hierro s/n, Madrid, Spain.
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Abstract
DEAD-box RNA helicases are important players in eukaryotic and bacterial RNA metabolism. A helicase from Staphylococcus aureus was recently shown to affect RNA decay, most likely via its interaction with the proposed Gram-positive degradosome. Some, but not all, RNAs are stabilized when the helicase CshA is mutated, and among the affected RNAs is the agrBDCA mRNA, which is responsible for quorum sensing in S. aureus. We describe how the stabilization of agr mRNA (and others) can be measured and how to conduct assays to measure the effects of quorum-sensing defects, such as biofilm formation and hemolysin production.
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Ravikumar S, Yoo IK, Lee SY, Hong SH. Construction of Copper Removing Bacteria Through the Integration of Two-Component System and Cell Surface Display. Appl Biochem Biotechnol 2011; 165:1674-81. [DOI: 10.1007/s12010-011-9386-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Accepted: 09/12/2011] [Indexed: 10/17/2022]
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Chua SL, See Too WC, Khoo BY, Few LL. UBC and YWHAZ as suitable reference genes for accurate normalisation of gene expression using MCF7, HCT116 and HepG2 cell lines. Cytotechnology 2011; 63:645-54. [PMID: 21850463 DOI: 10.1007/s10616-011-9383-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 07/19/2011] [Indexed: 10/17/2022] Open
Abstract
Relative quantification of in vitro gene expression using real-time PCR requires stably expressed reference gene for normalisation. In this study, total RNA from MCF7, HCT116 and HepG2 cells were extracted and converted to cDNA using commercially available kit, and real-time PCR was then performed to analyse the expression levels of twelve reference genes to select the most ideal reference gene for accurate normalisation in gene expression study. geNorm and NormFinder software were used to analyse the stabilities of the reference genes, which showed a wide range of C(t) values. The geNorm analysis showed the following ranking for stability of genes: UBC, YWHAZ > RPLP > TBP > ACTB > HPRT1 > PPIA > GAPDH > GUSB > B2M > TUBB > RRN18S. A similar ranking of reference genes was obtained by NormFinder, and the four most stable reference genes were identical using both approaches. UBC and YWHAZ were proposed to be the two most suitable reference genes based on the above analyses. To further assess the stabilities of the UBC and YWHAZ in a formal experiment, MCF7, HCT116 and HepG2 cell lines were subjected to treatments with 5-aza-dC and TSA. Both UBC and YWHAZ exhibited stable expression levels across control and treatment groups. Therefore, we propose that UBC and YWHAZ are the two most suitable reference genes for our gene expression studies using MCF7, HCT116 and HepG2 cell lines.
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Affiliation(s)
- Siang Ling Chua
- School of Health Sciences, Universiti Sains Malaysia, 16150, Kubang Kerian, Kelantan, Malaysia
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