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Wu XL, Liu XW, Wang Y, Guo MY, Ye JR. Optimization of Constitutive Promoters Using a Promoter-Trapping Vector in Burkholderia pyrrocinia JK-SH007. Int J Mol Sci 2023; 24:ijms24119419. [PMID: 37298372 DOI: 10.3390/ijms24119419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/16/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023] Open
Abstract
Selecting suitable promoters to drive gene overexpression can provide significant insight into the development of engineered bacteria. In this study, we analyzed the transcriptome data of Burkholderia pyrrocinia JK-SH007 and identified 54 highly expressed genes. The promoter sequences were located using genome-wide data and scored using the prokaryotic promoter prediction software BPROM to further screen out 18 promoter sequences. We also developed a promoter trap system based on two reporter proteins adapted for promoter optimization in B. pyrrocinia JK-SH007: firefly luciferase encoded by the luciferase gene set (Luc) and trimethoprim (TP)-resistant dihydrofolate reductase (TPr). Ultimately, eight constitutive promoters were successfully inserted into the probe vector and transformed into B. pyrrocinia JK-SH007. The transformants were successfully grown on Tp antibiotic plates, and firefly luciferase expression was determined by measuring the relative light unit (RLU). Five of the promoters (P4, P9, P10, P14, and P19) showed 1.01-2.51-fold higher activity than the control promoter λ phage transcriptional promoter (PRPL). The promoter activity was further validated via qPCR analysis, indicating that promoters P14 and P19 showed stable high transcription levels at all time points. Then, GFP and RFP proteins were overexpressed in JK-SH007. In addition, promoters P14 and P19 were successfully used to drive gene expression in Burkholderia multivorans WS-FJ9 and Escherichia coli S17-1. The two constitutive promoters can be used not only in B. pyrrocinia JK-SH007 itself to gene overexpression but also to expand the scope of application.
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Affiliation(s)
- Xue-Lian Wu
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
- Jiangsu Key Laboratory for Prevention and Management of Invasive Species, Nanjing Forestry University, Nanjing 210037, China
| | - Xiao-Wei Liu
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
- Jiangsu Key Laboratory for Prevention and Management of Invasive Species, Nanjing Forestry University, Nanjing 210037, China
| | - Yang Wang
- Institute of Forest Pest Control, Jiangxi Academy of Forestry, Nanchang 330032, China
| | - Meng-Yun Guo
- Key Laboratory for Bio-Resources and Eco-Environment of Ministry of Education, College of Life Science, Sichuan University, Chengdu 610065, China
| | - Jian-Ren Ye
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
- Jiangsu Key Laboratory for Prevention and Management of Invasive Species, Nanjing Forestry University, Nanjing 210037, China
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Chen F, Ye J, Liu W, Chio C, Wang W, Qin W. Knockout of a highly GC-rich gene in Burkholderia pyrrocinia by recombineering with freeze-thawing transformation. Mol Plant Pathol 2021; 22:843-857. [PMID: 33942460 PMCID: PMC8232026 DOI: 10.1111/mpp.13058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 03/04/2021] [Accepted: 03/05/2021] [Indexed: 05/12/2023]
Abstract
Genetic transformation is a valuable and essential method that provides powerful insights into the gene function of microorganisms and contributes to the construction of engineered bacteria. Here, we developed a novel genetic transformation system to easily knock out a highly GC-rich gene (74.71% GC) from Burkholderia pyrrocinia JK-SH007, a biocontrol strain of poplar canker disease. This system revealed a reliable selectable marker (trimethoprim resistance gene, Tmp) and a simplified, efficient transformation method (6,363.64 CFU/μg, pHKT2) that was developed via freeze-thawing. The knockout recombineering of B. pyrrocinia JK-SH007 was achieved through a suicide plasmid with a three-fragment mutagenesis construct. The three-fragment cassette for mutagenesis was generated by overlap extension and touchdown PCRs and composed of Tmp flanked by GC-rich upstream and downstream fragments from B. pyrrocinia JK-SH007. The mutant strain (ΔBpEG), which was verified by PCR, lost 93.3% of its ability to degrade carboxymethyl cellulose over 40 days. Overall, this system may contribute to future research on B. pyrrocinia traits.
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Affiliation(s)
- Feifei Chen
- College of Forestry and Co‐Innovation Center for Sustainable Forestry in Southern ChinaJiangsu Key Laboratory for Prevention and Management of Invasive SpeciesNanjing Forestry UniversityNanjingJiangsuChina
- Department of BiologyLakehead UniversityThunder BayOntarioCanada
| | - Jianren Ye
- College of Forestry and Co‐Innovation Center for Sustainable Forestry in Southern ChinaJiangsu Key Laboratory for Prevention and Management of Invasive SpeciesNanjing Forestry UniversityNanjingJiangsuChina
| | - Wanhui Liu
- College of Forestry and Co‐Innovation Center for Sustainable Forestry in Southern ChinaJiangsu Key Laboratory for Prevention and Management of Invasive SpeciesNanjing Forestry UniversityNanjingJiangsuChina
| | - Chonlong Chio
- Department of BiologyLakehead UniversityThunder BayOntarioCanada
| | - Wendy Wang
- Department of BiologyLakehead UniversityThunder BayOntarioCanada
| | - Wensheng Qin
- Department of BiologyLakehead UniversityThunder BayOntarioCanada
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Pesce C, Oshone R, Hurst SG 4th, Kleiner VA, Tisa LS. Stable Transformation of the Actinobacteria Frankia spp. Appl Environ Microbiol 2019; 85:e00957-19. [PMID: 31152017 DOI: 10.1128/AEM.00957-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 05/24/2019] [Indexed: 11/20/2022] Open
Abstract
A stable and efficient plasmid transfer system was developed for nitrogen-fixing symbiotic actinobacteria of the genus Frankia, a key first step in developing a genetic system. Four derivatives of the broad-host-range cloning vector pBBR1MCS were successfully introduced into different Frankia strains by a filter mating with Escherichia coli strain BW29427. Initially, plasmid pHKT1 that expresses green fluorescent protein (GFP) was introduced into Frankia casuarinae strain CcI3 at a frequency of 4.0 × 10-3, resulting in transformants that were tetracycline resistant and exhibited GFP fluorescence. The presence of the plasmid was confirmed by molecular approaches, including visualization on agarose gel and PCR. Several other pBBR1MCS plasmids were also introduced into F. casuarinae strain CcI3 and other Frankia strains at frequencies ranging from 10-2 to 10-4, and the presence of the plasmids was confirmed by PCR. The plasmids were stably maintained for over 2 years and through passage in a plant host. As a proof of concept, a salt tolerance candidate gene from the highly salt-tolerant Frankia sp. strain CcI6 was cloned into pBBR1MCS-3. The resulting construct was introduced into the salt-sensitive F. casuarinae strain CcI3. Endpoint reverse transcriptase PCR (RT-PCR) showed that the gene was expressed in F. casuarinae strain CcI3. The expression provided an increased level of salt tolerance for the transformant. These results represent stable plasmid transfer and exogenous gene expression in Frankia spp., overcoming a major hurdle in the field. This step in the development of genetic tools in Frankia spp. will open up new avenues for research on actinorhizal symbiosis.IMPORTANCE The absence of genetic tools for Frankia research has been a major hindrance to the associated field of actinorhizal symbiosis and the use of the nitrogen-fixing actinobacteria. This study reports on the introduction of plasmids into Frankia spp. and their functional expression of green fluorescent protein and a cloned gene. As the first step in developing genetic tools, this technique opens up the field to a wide array of approaches in an organism with great importance to and potential in the environment.
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Schlechter RO, Remus-Emsermann MN. Delivering "Chromatic Bacteria" Fluorescent Protein Tags to Proteobacteria Using Conjugation. Bio Protoc 2019; 9:e3199. [PMID: 33654996 DOI: 10.21769/bioprotoc.3199] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 12/21/2022] Open
Abstract
Recently, we published a large and versatile set of plasmids, the chromatic bacteria toolbox, to deliver eight different fluorescent protein genes and four combinations of antibiotic resistance genes to Gram-negative bacteria. Fluorescent tags are important tools for single-cell microbiology, synthetic community studies, biofilm, and host-microbe interaction studies. Using conjugation helper strain E. coli S17-1 as a donor, we show how plasmid conjugation can be used to deliver broad host range plasmids, Tn5 transposons delivery plasmids, and Tn7 transposon delivery plasmids into species belonging to the Proteobacteria. To that end, donor and recipient bacteria are grown under standard growth conditions before they are mixed and incubated under non-selective conditions. Then, transconjugants or exconjugant recipients are selected on selective media. Mutant colonies are screened using a combination of tools to ensure that the desired plasmids or transposons are present and that the colonies are not containing any surviving donors. Through conjugation, a wide range of Gram-negative bacteria can be modified without prior, often time-consuming, establishment of competent cell and electroporation procedures that need to be adjusted for every individual strain. The here presented protocol is not exclusive for the delivery of Chromatic bacteria plasmids and transposons, but can also be used to deliver other mobilizable plasmids to bacterial recipients.
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Affiliation(s)
- Rudolf O Schlechter
- School of Biological Sciences and Biomolecular Interaction Centre, University of Canterbury, Christchurch, New Zealand
| | - Mitja Np Remus-Emsermann
- School of Biological Sciences and Biomolecular Interaction Centre, University of Canterbury, Christchurch, New Zealand
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Mun W, Kwon H, Im H, Choi SY, Monnappa AK, Mitchell RJ. Cyanide Production by Chromobacterium piscinae Shields It from Bdellovibrio bacteriovorus HD100 Predation. mBio 2017; 8:e01370-17. [PMID: 29259082 DOI: 10.1128/mBio.01370-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Predation of Chromobacterium piscinae by Bdellovibrio bacteriovorus HD100 was inhibited in dilute nutrient broth (DNB) but not in HEPES. Experiments showed that the effector responsible was present in the medium, as cell-free supernatants retained the ability to inhibit predation, and that the effector was not toxic to B. bacteriovorus. Violacein, a bisindole secondary metabolite produced by C. piscinae, was not responsible. Further characterization of C. piscinae found that this species produces sufficient concentrations of cyanide (202 µM) when grown in DNB to inhibit the predatory activity of B. bacteriovorus, but that in HEPES, the cyanide concentrations were negligible (19 µM). The antagonistic role of cyanide was further confirmed, as the addition of hydroxocobalamin, which chelates cyanide, allowed predation to proceed. The activity of cyanide against B. bacteriovorus was found to be twofold, depending on the life cycle stage of this predator. For the attack-phase predatory cells, cyanide caused the cells to lose motility and tumble, while for intraperiplasmic predators, development and lysis of the prey cell were halted. These findings suggest that cyanogenesis in nature may be employed by the bacterial strains that produce this compound to prevent and reduce their predation by B. bacteriovorus. Bacterial predators actively attack, kill, and enter the periplasm of susceptible Gram-negative bacteria, where they consume the prey cell components. To date, the activity of B. bacteriovorus HD100 has been demonstrated against more than 100 human pathogens. As such, this strain and others are being considered as potential alternatives or supplements to conventional antibiotics. However, the production of secondary metabolites by prey bacteria is known to mitigate, and even abolish, predation by bacterivorous nematodes and protists. With the exception of indole, which was shown to inhibit predation, the effects of bacterial secondary metabolites on B. bacteriovorus and its activities have not been considered. Consequently, we undertook this study to better understand the mechanisms that bacterial strains employ to inhibit predation by B. bacteriovorus HD100. We report here that cyanogenic bacterial strains can inhibit predation and show that cyanide affects both attack-phase predators and those within prey, i.e., in the bdelloplast.
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Li Y, Wu C, Xing Z, Gao B, Zhang L. Engineering the bacterial endophyte Burkholderia pyrrocinia JK-SH007 for the control of lepidoptera larvae by introducing the cry218 genes of Bacillus thuringiensis. BIOTECHNOL BIOTEC EQ 2017. [DOI: 10.1080/13102818.2017.1379361] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Yang Li
- Jiangsu Key Laboratory for Prevention and Management of Invasive Species, College of Forest, Nanjing Forestry University, Nanjing, PR China
| | - Choufei Wu
- Collaborative Innovation Center of Green Pesticide, College of Life Science, Huzhou University, Huzhou, PR China
| | - Zhong Xing
- Department of Biology and Chemistry Engineering, College of Zhixing, Hubei University, Wuhan, PR China
| | - Bingli Gao
- Collaborative Innovation Center of Green Pesticide, College of Life Science, Huzhou University, Huzhou, PR China
| | - Liqin Zhang
- Jiangsu Key Laboratory for Prevention and Management of Invasive Species, College of Forest, Nanjing Forestry University, Nanjing, PR China
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Everaert A, Coenye T. Effect of β-Lactamase inhibitors on in vitro activity of β-Lactam antibiotics against Burkholderia cepacia complex species. Antimicrob Resist Infect Control 2016; 5:44. [PMID: 27895902 PMCID: PMC5111247 DOI: 10.1186/s13756-016-0142-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 10/17/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bacteria belonging to the Burkholderia cepacia complex (Bcc) are an important cause of chronic respiratory tract infections in cystic fibrosis patients. Intrinsic resistance to a wide range of antimicrobial agents, including a variety of β-lactam antibiotics, is frequently observed in Bcc strains. Resistance to β-lactams is most commonly mediated by efflux pumps, alterations in penicillin-binding proteins or the expression of β-lactamases. β-lactamase inhibitors are able to restore the in vitro activity of β-lactam molecules against a variety of Gram-negative species, but the effect of these inhibitors on the activity of β-lactam treatment against Bcc species is still poorly investigated. METHODS In the present study, the susceptibility of a panel of Bcc strains was determined towards the β-lactam antibiotics ceftazidime, meropenem, amoxicillin, cefoxitin, cefepime and aztreonam; alone or in combination with a β-lactamase inhibitor (clavulanic acid, sulbactam, tazobactam and avibactam). Consequently, β-lactamase activity was determined for active β-lactam/β-lactamase inhibitor combinations. RESULTS Clavulanic acid had no effect on minimum inhibitory concentrations, but addition of sulbactam, tazobactam or avibactam to ceftazidime, amoxicillin, cefoxitin, cefepime or aztreonam leads to increased susceptibility (at least 4-fold MIC-decrease) in some Bcc strains. The effect of β-lactamase inhibitors on β-lactamase activity is both strain- and/or antibiotic-dependent, and other mechanisms of β-lactam resistance (besides production of β-lactamases) appear to be important. CONCLUSIONS Considerable differences in susceptibility of Bcc strains to β-lactam antibiotics were observed. Results obtained in the present study suggest that resistance of Bcc strains against β-lactam antibiotics is mediated by both β-lactamases and non-β-lactamase-mediated resistance mechanisms.
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Affiliation(s)
- Annelien Everaert
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
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Wijers CDM, Vagedes R, Weingart C. A novel method for investigating Burkholderia cenocepacia infections in patients with cystic fibrosis and other chronic diseases of the airways. BMC Microbiol 2016; 16:200. [PMID: 27586172 PMCID: PMC5009706 DOI: 10.1186/s12866-016-0811-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/18/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Burkholderia cenocepacia is a Gram-negative, opportunistic pathogen that is a cause of morbidity and mortality in patients with cystic fibrosis (CF). Research efforts over the past few decades contributed to our understanding of these infections by identifying virulence factors. However, little is known about how this pathogen adapts to the harsh environment found inside the CF airways, which is characterized by a unique mucus containing high concentrations of inflammatory markers. The current study developed a novel model to further investigate this phenomenon. RESULTS Monolayers of human A549 lung carcinoma cells (HLCCs) were exposed to a mixture of artificial CF sputum medium (ASMDM) in tissue culture growth medium, and subsequently infected with B. cenocepacia K56-2 for 24 h. The data showed that this model supported B. cenocepacia growth. In addition, consistent with similar studies using current models such as CF airway tissue samples, HLCC viability was reduced by more than 70 % when grown in 60 % ASMDM and infected with B. cenocepacia compared to mock-infected controls and medium alone. Furthermore, the amount of B. cenocepacia cells associated with the HLCC monolayer was more than 10 times greater in 60 % ASMDM when compared to medium controls. CONCLUSIONS These findings suggest that HLCC monolayers in 60 % ASMDM serve as a valid alternative to study B. cenocepacia infections in patients with CF, and possibly other chronic diseases of the airways. Furthermore, the results obtained in this study suggest an important role for CF sputum in B. cenocepacia pathogenesis.
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Affiliation(s)
- Christiaan D M Wijers
- Department of Biological Sciences, Denison University, 100 West College Street, Granville, OH, 43023, USA
| | - Ryan Vagedes
- Department of Biological Sciences, Denison University, 100 West College Street, Granville, OH, 43023, USA
| | - Christine Weingart
- Department of Biological Sciences, Denison University, 100 West College Street, Granville, OH, 43023, USA.
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Chen D, Zhao T, Doyle MP. Single- and mixed-species biofilm formation by Escherichia coli O157:H7 and Salmonella, and their sensitivity to levulinic acid plus sodium dodecyl sulfate. Food Control 2015. [DOI: 10.1016/j.foodcont.2015.04.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Cohen D, Mechold U, Nevenzal H, Yarmiyhu Y, Randall TE, Bay DC, Rich JD, Parsek MR, Kaever V, Harrison JJ, Banin E. Oligoribonuclease is a central feature of cyclic diguanylate signaling in Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 2015; 112:11359-64. [PMID: 26305928 DOI: 10.1073/pnas.1421450112] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The second messenger cyclic diguanylate (c-di-GMP) controls diverse cellular processes among bacteria. Diguanylate cyclases synthesize c-di-GMP, whereas it is degraded by c-di-GMP-specific phosphodiesterases (PDEs). Nearly 80% of these PDEs are predicted to depend on the catalytic function of glutamate-alanine-leucine (EAL) domains, which hydrolyze a single phosphodiester group in c-di-GMP to produce 5'-phosphoguanylyl-(3',5')-guanosine (pGpG). However, to degrade pGpG and prevent its accumulation, bacterial cells require an additional nuclease, the identity of which remains unknown. Here we identify oligoribonuclease (Orn)-a 3'→5' exonuclease highly conserved among Actinobacteria, Beta-, Delta- and Gammaproteobacteria-as the primary enzyme responsible for pGpG degradation in Pseudomonas aeruginosa cells. We found that a P. aeruginosa Δorn mutant had high intracellular c-di-GMP levels, causing this strain to overexpress extracellular polymers and overproduce biofilm. Although recombinant Orn degraded small RNAs in vitro, this enzyme had a proclivity for degrading RNA oligomers comprised of two to five nucleotides (nanoRNAs), including pGpG. Corresponding with this activity, Δorn cells possessed highly elevated pGpG levels. We found that pGpG reduced the rate of c-di-GMP degradation in cell lysates and inhibited the activity of EAL-dependent PDEs (PA2133, PvrR, and purified recombinant RocR) from P. aeruginosa. This pGpG-dependent inhibition was alleviated by the addition of Orn. These data suggest that elevated levels of pGpG exert product inhibition on EAL-dependent PDEs, thereby increasing intracellular c-di-GMP in Δorn cells. Thus, we propose that Orn provides homeostatic control of intracellular pGpG under native physiological conditions and that this activity is fundamental to c-di-GMP signal transduction.
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Cheng Z, Meng X, Xie L, Xu H, Li M. Nutrition effects on the biofilm immobilization and 3,5-DNBA degradation ofComamonas testosteroniA3 during bioaugmentation treatment. Biotechnol Appl Biochem 2014; 62:719-25. [DOI: 10.1002/bab.1314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 10/17/2014] [Indexed: 02/06/2023]
Affiliation(s)
- Zhongqin Cheng
- School of Biology and Basic Medical Sciences; Soochow University; Suzhou People's Republic of China
| | - Xiangxun Meng
- School of Biology and Basic Medical Sciences; Soochow University; Suzhou People's Republic of China
| | - Liqun Xie
- School of Biology and Basic Medical Sciences; Soochow University; Suzhou People's Republic of China
| | - Hongqing Xu
- School of Biology and Basic Medical Sciences; Soochow University; Suzhou People's Republic of China
| | - Mengying Li
- School of Biology and Basic Medical Sciences; Soochow University; Suzhou People's Republic of China
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Dwidar M, Nam D, Mitchell RJ. Indole negatively impacts predation byBdellovibrio bacteriovorusand its release from the bdelloplast. Environ Microbiol 2014; 17:1009-22. [DOI: 10.1111/1462-2920.12463] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/21/2014] [Accepted: 03/23/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Mohammed Dwidar
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan 689-798 Korea
| | - Dougu Nam
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan 689-798 Korea
| | - Robert J. Mitchell
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan 689-798 Korea
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Cheng Z, Meng X, Wang H, Chen M, Li M. Isolation and characterization of broad spectrum coaggregating bacteria from different water systems for potential use in bioaugmentation. PLoS One 2014; 9:e94220. [PMID: 24736645 PMCID: PMC3988075 DOI: 10.1371/journal.pone.0094220] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 03/13/2014] [Indexed: 01/30/2023] Open
Abstract
The bridging bacteria with broad-spectrum coaggregation ability play an important role during multispecies-biofilm development. In this study, through a visual and semi-quantitative assay, twenty-two bacterial strains with aggregation ability were obtained from 8 different water environments, and these strains were assigned to 7 genera according to their 16S rDNA and they were Aeromonas, Bacillus, Comamonas, Exiguobacterium, Pseudomonas, Shewanella and Comamonas. Furthermore, all possible 231 pairwise combinations among these 22 strains were explored for coaggregation ability by spectrophotometric assay. Among all these strains, it was found that Bacillus cereus G5 and Bacillus megaterium T1 coaggregated with themajority of assayed other strains, 90.5% (19 of 21 strains) and 76.2% respectively (17 of 21 strains) at a higher coaggregation rates (A.I. greater than 50%), indicating they have a broad-spectrum coaggregation property. The images of coaggregates also confirmed the coexistence of G5 and T1 with their partner strains. Biofilm biomass development of G5 cocultured with each of its partner strains were further evaluateded. The results showed that 15 of 21 strains, when paired with G5, developed greater biofilm biomass than the monocultures. Furthermore, the images from both fluorescence microscopy and scanning electron microscopy (SEM) demonstrated that G5 and A3-GFP (a 3,5-dinitrobenzoic acid-degrading strain, staining with gfp),could develop a typical spatial structure of dual-species biofilm when cocultured. These results suggested that bridging-bacteria with a broad spectrum coaggregating ability, such as G5,could mediate the integration of exogenous degrading bacteria into biofilms and contribute to the bioaugmentation treatment.
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Affiliation(s)
- Zhongqin Cheng
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, PR China
| | - Xiangxun Meng
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, PR China
| | - Haichao Wang
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, PR China
| | - Mei Chen
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, PR China
| | - Mengying Li
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou, PR China
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Im H, Kim D, Ghim CM, Mitchell RJ. Shedding light on microbial predator-prey population dynamics using a quantitative bioluminescence assay. Microb Ecol 2014; 67:167-176. [PMID: 24272279 DOI: 10.1007/s00248-013-0323-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/29/2013] [Indexed: 06/02/2023]
Abstract
This study assessed the dynamics of predation by Bdellovibrio bacteriovorus HD 100. Predation tests with two different bioluminescent strains of Escherichia coli, one expressing a heat-labile bacterial luciferase and the other a heat-stable form, showed near identical losses from both, indicating that protein expression and stability are not responsible for the "shutting-off" of the prey bioluminescence (BL). Furthermore, it was found that the loss in the prey BL was not proportional with the predator-to-prey ratio (PPR), with significantly greater losses seen as this value was increased. This suggests that other factors also play a role in lowering the prey BL. The loss in BL, however, was very consistent within nine independent experiments to the point that we were able to reliably estimate the predator numbers within only 1 h when present at a PPR of 6 or higher, Using a fluorescent prey, we found that premature lysis of the prey occurs at a significant level and was more prominent as the PPR ratio increased. Based upon the supernatant fluorescent signal, even a relatively low PPR of 10-20 led to approximately 5% of the prey population being prematurely lysed within 1 h, while a PPR of 90 led to nearly 15% lysis. Consequently, we developed a modified Lotka-Volterra predator-prey model that accounted for this lysis and is able to reliably estimate the prey and bdelloplast populations for a wide range of PPRs.
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Affiliation(s)
- Hansol Im
- School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 689-798, South Korea
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Abstract
We describe a novel method which makes use of polymer-based aqueous two-phase systems to pattern bacterial communities inside Petri dishes. This method allows us to culture submillimeter-sized bacterial communities in spatially distinct spots while maintaining a degree of chemical connectedness to each other through the aqueous phase. Given sufficient time, these bacterial cultures develop biofilms, each corresponding to the footprint of the droplet spot. This method can be used to study the interactions between bacterial communities and biofilms spotted adjacent to each other. Furthermore, it can be extended to study the interactions between different bacterial communities and an underlying epithelial cell layer.
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Affiliation(s)
- Mohammed Dwidar
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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16
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Abstract
Micropatterning of bacteria using aqueous two phase system (ATPS) enables the localized culture and formation of physically separated bacterial communities on human epithelial cell sheets. This method was used to compare the effects of Escherichia coli strain MG1655 and an isogenic invasive counterpart that expresses the invasin (inv) gene from Yersinia pseudotuberculosis on the underlying epithelial cell layer. Large portions of the cell layer beneath the invasive strain were killed or detached while the non-invasive E. coli had no apparent effect on the epithelial cell layer over a 24 h observation period. In addition, simultaneous testing of the localized effects of three different bacterial species; E. coli MG1655, Shigella boydii KACC 10792 and Pseudomonas sp DSM 50906 on an epithelial cell layer is also demonstrated. The paper further shows the ability to use a bacterial predator, Bdellovibriobacteriovorus HD 100, to selectively remove the E. coli, S. boydii and P. sp communities from this bacteria-patterned epithelial cell layer. Importantly, predation and removal of the P. Sp was critical for maintaining viability of the underlying epithelial cells. Although this paper focuses on a few specific cell types, the technique should be broadly applicable to understand a variety of bacteria-epithelial cell interactions.
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Affiliation(s)
- Mohammed Dwidar
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Brendan M. Leung
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Toshiyuki Yaguchi
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- Nagoya Institute of Technology, Biomechanics Laboratory, Gokiso-cho, Showa-ku, Nagoya, Japan
| | - Shuichi Takayama
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- Department Biomedical Engineering and Macromolecular Science & Engineering Program, University of Michigan, Ann Arbor, United States of America
| | - Robert J. Mitchell
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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17
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Correa-Ruiz A, Girón R, Buendía B, Medina-Pascual MJ, Valenzuela C, López-Brea M, Sáez-Nieto JA. Burkholderia cepacia complex infection in an Adult Cystic Fibrosis unit in Madrid. Enferm Infecc Microbiol Clin 2013; 31:649-54. [PMID: 23528342 DOI: 10.1016/j.eimc.2012.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 11/30/2012] [Accepted: 12/04/2012] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Burkholderia cepacia complex have emerged as significant pathogens in cystic fibrosis (CF) patients due to the risk of cepacia syndrome and the innate multi-resistance of the microorganisms to antibiotics. The aim of this study was to describe the antimicrobial susceptibility profiles, the genotypes and subtypes of BCC, and the clinical evolution of CF patients with BCC. METHODS The lung function and Brasfield and Shwachman score were assessed in 12 patients. BCC were identified and susceptibility was studied by MicroScan (Siemens). Species and genospecies of BCC were confirmed by molecular methods in a Reference Centre (Majadahonda). RESULTS BCC were identified in 12 of 70 patients (17.1%) over a ten year period. The mean age to colonization by BCC was 24.4 years (SD: 7.71). B. cenocepacia was isolated in 4 patients (33.3%), B. contaminans was isolated in 3 patients (25%), both B. vietnamiensis and B. stabilis were isolated in 2 patients (16.7%), and B. cepacia, B. multivorans and B. late were isolated in one patient (8.3%). Among the B. cenocepacia, subtype IIIa was identified in two strains, and subtype IIIb was identified in the other two strains. There was susceptibility to meropenem in 90% of BCC, 80% to cotrimoxazole, 60% to minocycline, 50% to ceftazidime, and 40% to levofloxacin. CONCLUSIONS B. cenocepacia was the most prevalent species among the BCC isolated in CF adult patients, and subtypes IIIa and IIIb were identified in the 50% of the strains. Meropenem and cotrimoxazole showed the best activity.
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Affiliation(s)
- Ana Correa-Ruiz
- Servicio de Microbiología, Instituto de Investigación Sanitaria, Hospital de La Princesa, Madrid, Spain.
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18
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Yaguchi T, Dwidar M, Byun CK, Leung B, Lee S, Cho YK, Mitchell RJ, Takayama S. Aqueous two-phase system-derived biofilms for bacterial interaction studies. Biomacromolecules 2012; 13:2655-61. [PMID: 22793044 DOI: 10.1021/bm300500y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We describe patterning of bacterial biofilms using polymer-based aqueous two-phase system (ATPS) microprinting protocols. The fully aqueous but selectively bacteria-partitioning nature of the ATPS allows spatially distinct localization of suspensions of bacteria such as Pseudomonas aeruginosa and Escherichia coli with high precision. The ATPS patterned bacterial suspensions form spatially distinct biofilms over time. Due to the fully aqueous and gentle noncontact printing procedures employed, coculture biofilms composed of multiple types of bacteria could be printed not only adjacent to each other but also directly over another layer of existing biofilm. In addition, the ATPS environment also allows free diffusion of small molecules between spatially distinct and localized bacterial suspensions and biofilms. This enables biofilms to chemically affect or be affected by neighboring biofilms or planktonic cells, even if they consist of different strains or species. We show that a β-lactamase producing biofilm confers ampicillin resistance to neighboring nonresistant planktonic cells, as seen by a 3,600-fold increase in survival of the ampicillin-sensitive strain. These examples demonstrate the ability of ATPS-based biofilm patterning methods to enable unique studies on commensalistic effects between bacterial species.
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Affiliation(s)
- Toshiyuki Yaguchi
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Banyeon-ri 100, Ulsan, 689-798, Republic of Korea
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19
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Ebert BE, Kurth F, Grund M, Blank LM, Schmid A. Response of Pseudomonas putida KT2440 to increased NADH and ATP demand. Appl Environ Microbiol 2011; 77:6597-605. [PMID: 21803911 DOI: 10.1128/AEM.05588-11] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adenosine phosphate and NAD cofactors play a vital role in the operation of cell metabolism, and their levels and ratios are carefully regulated in tight ranges. Perturbations of the consumption of these metabolites might have a great impact on cell metabolism and physiology. Here, we investigated the impact of increased ATP hydrolysis and NADH oxidation rates on the metabolism of Pseudomonas putida KT2440 by titration of 2,4-dinitrophenol (DNP) and overproduction of a water-forming NADH oxidase, respectively. Both perturbations resulted in a reduction of the biomass yield and, as a consequence of the uncoupling of catabolic and anabolic activities, in an amplification of the net NADH regeneration rate. However, a stimulation of the specific carbon uptake rate was observed only when P. putida was challenged with very high 2,4-dinitrophenol concentrations and was comparatively unaffected by recombinant NADH oxidase activity. This behavior contrasts with the comparably sensitive performance described, for example, for Escherichia coli or Saccharomyces cerevisiae. The apparent robustness of P. putida metabolism indicates that it possesses a certain buffering capacity and a high flexibility to adapt to and counteract different stresses without showing a distinct phenotype. These findings are important, e.g., for the development of whole-cell redox biocatalytic processes that impose equivalent burdens on the cell metabolism: stoichiometric consumption of (reduced) redox cofactors and increased energy expenditures, due to the toxicity of the biocatalytic compounds.
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20
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Moazeni E, Gilani K, Sotoudegan F, Pardakhty A, Najafabadi AR, Ghalandari R, Fazeli MR, Jamalifar H. Formulation and in vitro evaluation of ciprofloxacin containing niosomes for pulmonary delivery. J Microencapsul 2011; 27:618-27. [PMID: 20681747 DOI: 10.3109/02652048.2010.506579] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In order to develop a niosome-encapsulated ciprofloxacin (CPFX) HCl formulation for pulmonary delivery, the feasibility of encapsulation of CPFX in niosomes, its stability and nebulization capability was evaluated. Various combinations of nonionic surfactants with cholesterol were used to prepare the formulations. The in vitro deposition data of the niosomal formulations were examined using an Andersen cascade impactor. Formulations composed of Span 60 and Tween 60 in combination with 40 mol% of cholesterol exhibited high encapsulation efficacy and stability and also had fine particle fraction and nebulization efficiency of about 61.9% ± 1.0 and 77.9 ± 2.8, respectively. Minimal inhibitory concentration of the niosomal CPFX against some pulmonary pathogens were lower than free CPFX. Using the MTT assay in human lung carcinoma cell line (A549), niosome-entrapped CPFX showed significantly lower cytotoxicity in comparison to the free drug. These results indicate that niosome can be used as a carrier for pulmonary delivery of CPFX via nebulization.
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Affiliation(s)
- Esmaeil Moazeni
- Aerosol Research Laboratory, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
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21
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Abstract
Starting with the first publication of lacZ gene fusion in 1980, reporter genes have just entered their fourth decade. Initial studies relied on the simple fusion of a promoter or gene with a particular reporter gene of interest. Such constructs were then used to determine the promoter activity under specific conditions or within a given cell or organ. Although this protocol was, and still is, very effective, current research shows a paradigm shift has occurred in the use of reporter systems. With the advent of innovative cloning and synthetic biology techniques and microfluidic/nanodroplet systems, reporter genes and their proteins are now finding themselves used in increasingly intricate and novel applications. For example, researchers have used fluorescent proteins to study biofilm formation and discovered that microchannels develop within the biofilm. Furthermore, there has recently been a "fusion" of art and science; through the construction of genetic circuits and regulatory systems, researchers are using bacteria to "paint" pictures based upon external stimuli. As such, this review will discuss the past and current trends in reporter gene applications as well as some exciting potential applications and models that are being developed based upon these remarkable proteins.
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Affiliation(s)
- Cheol-Min Ghim
- Ulsan National Institute of Science and Technology, Korea
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22
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Abstract
Burkholderia cepacia complex bacteria are opportunistic pathogens that cause respiratory tract infections in susceptible patients, mainly people with cystic fibrosis. There is convincing evidence that B. cepacia complex bacteria can form biofilms, not only on abiotic surfaces (e.g., glass and plastics), but also on biotic surfaces such as epithelial cells, leading to the suggestion that biofilm formation plays a key role in persistent infection of cystic fibrosis lungs. This article presents an overview of the molecular mechanisms involved in B. cepacia complex biofilm formation, the increased resistance of sessile B. cepacia complex cells and the role of quorum sensing in B. cepacia complex biofilm formation.
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Affiliation(s)
- Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, B-9000 Gent, Belgium
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Hwang J, Mattei LM, VanArendonk LG, Meneely PM, Okeke IN. A pathoadaptive deletion in an enteroaggregative Escherichia coli outbreak strain enhances virulence in a Caenorhabditis elegans model. Infect Immun 2010; 78:4068-76. [PMID: 20584976 DOI: 10.1128/IAI.00014-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulent E. coli subtypes of Shigella and enterohemorrhagic E. coli. To test the hypothesis that cad deletions might account for heterogeneity in EAEC virulence, we developed a Caenorhabditis elegans pathogenesis model. Well-characterized EAEC strains were shown to colonize and kill C. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysine in vitro due to deletions in cadA and cadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of the cadAB genes. Strain 101-1 was significantly more lethal to C. elegans than control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion of cad genes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.
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Hong SH, Wang X, Wood TK. Controlling biofilm formation, prophage excision and cell death by rewiring global regulator H-NS of Escherichia coli. Microb Biotechnol 2010; 3:344-56. [PMID: 21255333 PMCID: PMC3158429 DOI: 10.1111/j.1751-7915.2010.00164.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/28/2009] [Accepted: 01/07/2010] [Indexed: 11/29/2022] Open
Abstract
The global regulator H-NS of Escherichia coli controls genes related to stress response, biofilm formation and virulence by recognizing curved DNA and by silencing acquired genes. Here, we rewired H-NS to control biofilm formation using protein engineering; H-NS variant K57N was obtained that reduces biofilm formation 10-fold compared with wild-type H-NS (wild-type H-NS increases biofilm formation whereas H-NS K57N reduces it). Whole-transcriptome analysis revealed that H-NS K57N represses biofilm formation through its interaction with the nucleoid-associated proteins Cnu and StpA and in the absence of these proteins, H-NS K57N was unable to reduce biofilm formation. Significantly, H-NS K57N enhanced the excision of defective prophage Rac while wild-type H-NS represses excision, and H-NS controlled only Rac excision among the nine resident E. coli K-12 prophages. Rac prophage excision not only led to the change in biofilm formation but also resulted in cell lysis through the expression of toxin HokD. Hence, the H-NS regulatory system may be evolved through a single-amino-acid change in its N-terminal oligomerization domain to control biofilm formation, prophage excision and apoptosis.
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Affiliation(s)
| | | | - Thomas K. Wood
- Department of Chemical Engineering, Texas A & M University, College Station, TX 77843‐3122, USA
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25
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Maher S, Leonard TW, Jacobsen J, Brayden DJ. Safety and efficacy of sodium caprate in promoting oral drug absorption: from in vitro to the clinic. Adv Drug Deliv Rev 2009; 61:1427-49. [PMID: 19800376 DOI: 10.1016/j.addr.2009.09.006] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 09/21/2009] [Accepted: 09/24/2009] [Indexed: 12/12/2022]
Abstract
A major challenge in oral drug delivery is the development of novel dosage forms to promote absorption of poorly permeable drugs across the intestinal epithelium. To date, no absorption promoter has been approved in a formulation specifically designed for oral delivery of Class III molecules. Promoters that are designated safe for human consumption have been licensed for use in a recently approved buccal insulin spray delivery system and also for many years as part of an ampicillin rectal suppository. Unlike buccal and rectal delivery, oral formulations containing absorption promoters have the additional technical hurdle whereby the promoter and payload must be co-released in high concentrations at the small intestinal epithelium in order to generate significant but rapidly reversible increases in permeability. An advanced promoter in the clinic is the medium chain fatty acid (MCFA), sodium caprate (C(10)), a compound already approved as a food additive. We discuss how it has evolved to a matrix tablet format suitable for administration to humans under the headings of mechanism of action at the cellular and tissue level as well as in vitro and in vivo efficacy and safety studies. In specific clinical examples, we review how C(10)-based formulations are being tested for oral delivery of bisphosphonates using Gastro Intestinal Permeation Enhancement Technology, GIPET (Merrion Pharmaceuticals, Ireland) and in a related solid dose format for antisense oligonucleotides (ISIS Pharmaceuticals, USA).
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Affiliation(s)
- Sam Maher
- UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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26
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Makidon PE, Knowlton J, Groom JV 2nd, Blanco LP, LiPuma JJ, Bielinska AU, Baker JR Jr. Induction of immune response to the 17 kDa OMPA Burkholderia cenocepacia polypeptide and protection against pulmonary infection in mice after nasal vaccination with an OMP nanoemulsion-based vaccine. Med Microbiol Immunol 2010; 199:81-92. [PMID: 19967396 DOI: 10.1007/s00430-009-0137-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Indexed: 10/20/2022]
Abstract
Burkholderia cepacia complex (Bcc) are opportunistic bacteria associated with life-threatening illness in persons with cystic fibrosis. Once Bcc colonization is established, these antimicrobial-resistant and biofilm-forming bacteria are difficult to eradicate and are associated with increased rates of morbidity and mortality. At present, no vaccines are available to prevent the Bcc infection. There is currently a paucity of published information regarding the development of vaccines designed to prevent Burkholderia colonization. This work expands on the recent studies published by Bertot et al. [Infect Immun 75(6):2740-2752, 2007], where successful protective immune responses were generated in mice using a B. multivorans OMP-based vaccine. Here, we evaluate an experimental mucosal vaccine against Bcc using a novel mucosal adjuvant (nanoemulsion) and a novel B. cenocepacia-based OMP antigen. The OMP antigen derived from B. cenocepacia was mixed with either nanoemulsion or with PBS and delivered intranasally to CD-1 mice. Serum analysis showed robust IgG and mucosal secretory IgA immune responses in vaccinated versus control mice. The antibodies had cross-neutralizing activity against both B. cenocepacia and B. multivorans species. We found that immunized mice were protected against pulmonary colonization with B. cenocepacia. We have also identified that a 17 kDa OmpA-like protein highly conserved between Burkholderia and Ralstonia species as a new immunodominant epitope in mucosal immunization.
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27
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Cooper VS, Carlson WA, LiPuma JJ. Susceptibility of Caenorhabditis elegans to Burkholderia infection depends on prior diet and secreted bacterial attractants. PLoS One 2009; 4:e7961. [PMID: 19956737 PMCID: PMC2776534 DOI: 10.1371/journal.pone.0007961] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 10/17/2009] [Indexed: 12/05/2022] Open
Abstract
The nematode Caenorhabditis elegans may be killed by certain pathogenic bacteria and thus is a model organism for studying interactions between bacteria and animal hosts. However, growing nematodes on prey bacteria may influence their susceptibility to potential pathogens. A method of axenic nematode culture was developed to isolate and quantify interactions between C. elegans and potentially pathogenic strains of the Burkholderia cepacia complex. Studying these dynamics in liquid solution rather than on agar surfaces minimized nematode avoidance behavior and resolved more differences among isolates. Most isolates of B. cenocepacia, B. ambifaria and B. cepacia caused 60–80% mortality of nematodes after 7 days, whereas isolates of B. multivorans caused less mortality (<25%) and supported nematode reproduction. However, some B. cenocepacia isolates recovered from chronic infections were much less virulent (5–28% mortality). As predicted, prior diet altered the outcome of interactions between nematodes and bacteria. When given the choice between Burkholderia and E. coli as prey on agar, axenically raised nematodes initially preferred most lethal Burkholderia isolates to E. coli as a food source, but this was not the case for nematodes fed E. coli, which avoided toxic Burkholderia. This food preference was associated with the cell-free supernatant and thus secreted compounds likely mediated bacterial-nematode interactions. This model, which isolates interactions between bacteria and nematodes from the effects of prior feeding, demonstrates that bacteria can influence nematode behavior and their susceptibility to pathogens.
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Affiliation(s)
- Vaughn S. Cooper
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, United States of America
- * E-mail:
| | - Wendy A. Carlson
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, United States of America
| | - John J. LiPuma
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
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Peeters E, Nelis HJ, Coenye T. In vitro activity of ceftazidime, ciprofloxacin, meropenem, minocycline, tobramycin and trimethoprim/sulfamethoxazole against planktonic and sessile Burkholderia cepacia complex bacteria. J Antimicrob Chemother 2009; 64:801-9. [PMID: 19633000 DOI: 10.1093/jac/dkp253] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES The goal of the present study was to obtain a comprehensive overview of the bacteriostatic and bactericidal effects of six commonly used antibiotics on planktonic as well as on sessile Burkholderia cepacia complex cells. METHODS The bacteriostatic and bactericidal activities of ceftazidime, ciprofloxacin, meropenem, minocycline, tobramycin and trimethoprim/sulfamethoxazole were determined against 38 B. cepacia complex strains. MICs and minimal biofilm inhibitory concentrations (MBICs) were determined using a traditional broth microdilution method and a novel resazurin-based viability staining, respectively. The bactericidal effects of the investigated antibiotics (using antibiotic concentrations corresponding to 10 x MIC; except for tobramycin, for which a final concentration of 4 x MIC was tested) on stationary phase planktonic cultures and on 24-h-old biofilms were evaluated using conventional plate count methods. RESULTS Our results confirm the innate resistance of B. cepacia complex organisms to six first-line antibiotics used to treat infected cystic fibrosis patients. All antibiotics showed similar bacteriostatic activities against exponentially growing B. cepacia complex planktonic cells and freshly adhered sessile cells (4 h). In addition, most of the antibiotics showed similar bactericidal effects on stationary phase planktonic cultures and on young and older biofilms. CONCLUSIONS Despite the general assumption that sessile cells show a decreased susceptibility to antibiotics, our data indicate similar bacteriostatic and bactericidal activity of six selected antibiotics against planktonic and sessile B. cepacia complex bacteria.
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Affiliation(s)
- Elke Peeters
- Laboratory of Pharmaceutical Microbiology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
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29
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Gross R, Lang K, Bühler K, Schmid A. Characterization of a biofilm membrane reactor and its prospects for fine chemical synthesis. Biotechnol Bioeng 2009; 105:705-17. [DOI: 10.1002/bit.22584] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Chan CS, Winstone TML, Chang L, Stevens CM, Workentine ML, Li H, Wei Y, Ondrechen MJ, Paetzel M, Turner RJ. Identification of Residues in DmsD for Twin-Arginine Leader Peptide Binding, Defined through Random and Bioinformatics-Directed Mutagenesis. Biochemistry 2008; 47:2749-59. [DOI: 10.1021/bi702138a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Catherine S. Chan
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Tara M. L. Winstone
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Limei Chang
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Charles M. Stevens
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Matthew L. Workentine
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Haiming Li
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Ying Wei
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Mary J. Ondrechen
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Mark Paetzel
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
| | - Raymond J. Turner
- Department of Biological Sciences, 2500 University Drive Northwest, University of Calgary, Calgary, Alberta T2N 1N4, Canada, Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada, and Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115
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Lee J, Jayaraman A, Wood TK. Indole is an inter-species biofilm signal mediated by SdiA. BMC Microbiol 2007; 7:42. [PMID: 17511876 DOI: 10.1186/1471-2180-7-42] [Citation(s) in RCA: 327] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Accepted: 05/18/2007] [Indexed: 01/07/2023] Open
Abstract
Background As a stationary phase signal, indole is secreted in large quantities into rich medium by Escherichia coli and has been shown to control several genes (e.g., astD, tnaB, gabT), multi-drug exporters, and the pathogenicity island of E. coli; however, its impact on biofilm formation has not been well-studied. Results Through a series of global transcriptome analyses, confocal microscopy, isogenic mutants, and dual-species biofilms, we show here that indole is a non-toxic signal that controls E. coli biofilms by repressing motility, inducing the sensor of the quorum sensing signal autoinducer-1 (SdiA), and influencing acid resistance (e.g., hdeABD, gadABCEX). Isogenic mutants showed these associated proteins are directly related to biofilm formation (e.g., the sdiA mutation increased biofilm formation 50-fold), and SdiA-mediated transcription was shown to be influenced by indole. The reduction in motility due to indole addition results in the biofilm architecture changing from scattered towers to flat colonies. Additionally, there are 12-fold more E. coli cells in dual-species biofilms grown in the presence of Pseudomonas cells engineered to express toluene o-monooxygenase (TOM, which converts indole to an insoluble indigoid) than in biofilms with pseudomonads that do not express TOM due to a 22-fold reduction in extracellular indole. Also, indole stimulates biofilm formation in pseudomonads. Further evidence that the indole effects are mediated by SdiA and homoserine lactone quorum sensing is that the addition of N-butyryl-, N-hexanoyl-, and N-octanoyl-L-homoserine lactones repress E. coli biofilm formation in the wild-type strain but not with the sdiA mutant. Conclusion Indole is an interspecies signal that decreases E. coli biofilms through SdiA and increases those of pseudomonads. Indole may be manipulated to control biofilm formation by oxygenases of bacteria that do not synthesize it in a dual-species biofilm. Furthermore, E. coli changes its biofilm in response to signals it cannot synthesize (homoserine lactones), and pseudomonads respond to signals they do not synthesize (indole).
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Partida-Martinez LP, Monajembashi S, Greulich KO, Hertweck C. Endosymbiont-dependent host reproduction maintains bacterial-fungal mutualism. Curr Biol 2007; 17:773-7. [PMID: 17412585 DOI: 10.1016/j.cub.2007.03.039] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 03/01/2007] [Accepted: 03/07/2007] [Indexed: 11/23/2022]
Abstract
Bacterial endosymbionts play essential roles for many organisms, and thus specialized mechanisms have evolved during evolution that guarantee the persistence of the symbiosis during or after host reproduction. The rice seedling blight fungus Rhizopus microsporus represents a unique example of a mutualistic life form in which a fungus harbors endobacteria (Burkholderia sp.) for the production of a phytotoxin. Here we report the unexpected observation that in the absence of endosymbionts, the host is not capable of vegetative reproduction. Formation of sporangia and spores is restored only upon reintroduction of endobacteria. To monitor this process, we succeeded in GFP labeling cultured endosymbionts. We also established a laserbeam transformation technique for the first controlled introduction of bacteria into fungi to observe their migration to the tips of the aseptate hyphae. The persistence of this fungal-bacterial mutualism through symbiont-dependent sporulation is intriguing from an evolutionary point of view and implies that the symbiont produces factors that are essential for the fungal life cycle. Reproduction of the host has become totally dependent on endofungal bacteria, which in return provide a highly potent toxin for defending the habitat and accessing nutrients from decaying plants. This scenario clearly highlights the significance for a controlled maintenance of this fungal-bacterial symbiotic relationship.
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Affiliation(s)
- Laila P Partida-Martinez
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, 07745 Jena, Germany
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Abstract
Escherichia coli O157:H7 can survive in low numbers in soil and on plants. Occasionally, conditions may occur in the field that lead to contamination of produce. Survival of enteric pathogens in the field is controlled to a certain extent by complex interactions with indigenous soilborne and seedborne epiphytes. Identifying these interactions may assist in developing strategies to improve produce safety. Two epiphytes were isolated from pathogen-contaminated plants that interact differently with E. coli O157:H7. Wausteria paucula enhanced the survival of E. coli O157:H7 six-fold on lettuce foliage grown from coinoculated lettuce seed. In contrast, Enterobacter asburiae decreased E. coli O157:H7 survival 20- to 30-fold on foliage. Competition also occurred in the rhizosphere and in plant exudate. This competition may be the result of E. asburiae utilization of several of the carbon and nitrogen substrates typically present in exudate and also used by E. coli O157:H7. Hence, competition observed on the plant may involve one or more nutrients provided by the plant. In contrast, a different mechanism may exist between E. coli O157:H7 and W. paucula since commensalism was only observed on foliage, not in the rhizosphere or plant exudate. Good agricultural practices that encourage the growth of competing bacteria, like E. asburiae, may reduce the incidence of produce contamination.
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Affiliation(s)
- Michael B Cooley
- Produce Safety and Microbiology Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, California 94710, USA.
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Abstract
Scanning of bacterial genomes to identify essential genes is of biological interest, for understanding the basic functions required for life, and of practical interest, for the identification of novel targets for new antimicrobial therapies. In particular, the lack of efficacious antimicrobial treatments for infections caused by the Burkholderia cepacia complex is causing high morbidity and mortality of cystic fibrosis patients and of patients with nosocomial infections. Here, we present a method based on delivery of the tightly regulated rhamnose-inducible promoter P(rhaB) for identifying essential genes and operons in Burkholderia cenocepacia. We demonstrate that different levels of gene expression can be achieved by using two vectors that deliver P(rhaB) at two different distances from the site of insertion. One of these vectors places P(rhaB) at the site of transposon insertion, while the other incorporates the enhanced green fluorescent protein gene (e-gfp) downstream from P(rhaB). This system allows us to identify essential genes and operons in B. cenocepacia and provides a new tool for systematically identifying and functionally characterizing essential genes at the genomic level.
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Affiliation(s)
- Silvia T Cardona
- Department of Microbiology and Immunology, Dental Sciences Building, Room 3014, The University of Western Ontario, London, Ontario, Canada N6A 5C1
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Abstract
When autofluorescent proteins (AFPs), such as green fluorescent protein (GFP) and Discosoma striata red fluorescent protein (DsRed), are excited with light of a specific wavelength, they emit light of a longer wavelength, without the further addition of substrates. A range of AFPs have been identified and cloned from marine organisms, and mutagenesis techniques have been employed to develop improved variant AFPs for applications in biological research. In recent years, AFP technology has become an important tool for microbiologists and microbial ecologists studying processes such as microbe-plant interactions, biosensors, biofilm formation, and horizontal gene transfer. The ability to use AFPs with differing fluorescent spectra within a single cell has allowed simultaneous monitoring of several aspects of microbial physiology and gene expression in situ in real time. This provides a tremendous insight into microbial function and behavior in natural environments. Furthermore, the integration of AFP reporters with other markers and technologies is facilitating a systems approach to research in microbial ecology.
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Tomlin KL, Malott RJ, Ramage G, Storey DG, Sokol PA, Ceri H. Quorum-sensing mutations affect attachment and stability of Burkholderia cenocepacia biofilms. Appl Environ Microbiol 2005; 71:5208-18. [PMID: 16151106 PMCID: PMC1214635 DOI: 10.1128/aem.71.9.5208-5218.2005] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Biofilm formation in Burkholderia cenocepacia has been shown to rely in part on acylhomoserine lactone-based quorum sensing. For many other bacterial species, it appears that both the initial adherence and the later stages of biofilm maturation are affected when quorum sensing pathways are inhibited. In this study, we examined the effects of mutations in the cepIR and cciIR quorum-sensing systems of Burkholderia cenocepacia K56-2 with respect to biofilm attachment and antibiotic resistance. We also examined the role of the cepIR system in biofilm stability and structural development. Using the high-throughput MBEC assay system to produce multiple equivalent biofilms, the biomasses of both the cepI and cepR mutant biofilms, measured by crystal violet staining, were less than half of the value observed for the wild-type strain. Attachment was partially restored upon providing functional gene copies via multicopy expression vectors. Surprisingly, neither the cciI mutant nor the double cciI cepI mutant was deficient in attachment, and restoration of the cciI gene resulted in less attachment than for the mutants. Meanwhile, the cciR mutant did show a significant reduction in attachment, as did the cciR cepIR mutant. While there was no change in antibiotic susceptibility with the individual cepIR and cciIR mutants, the cepI cciI mutant biofilms were more sensitive to ciprofloxacin. A significant increase in sensitivity to removal by sodium dodecyl sulfate was seen for the cepI and cepR mutants. Flow cell analysis of the individual cepIR mutant biofilms indicated that they were both structurally and temporally impaired in attachment and development. These results suggest that biofilm structural defects might be present in quorum-sensing mutants of B. cenocepacia that affect the stability and resistance of the adherent cell mass, providing a basis for future studies to design preventative measures against biofilm formation in this species, an important lung pathogen of cystic fibrosis patients.
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Affiliation(s)
- Kerry L Tomlin
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
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Abstract
PURPOSE OF REVIEW The Burkholderia cepacia complex is comprised of a group of related bacterial species that are capable of causing life-threatening respiratory tract infection in persons with cystic fibrosis. This article reviews advances in our understanding of Burkholderia cepacia complex infection in cystic fibrosis, focusing on the taxonomy, clinical microbiology, and epidemiology, as well as the natural history and clinical outcomes associated with Burkholderia cepacia complex infection. RECENT FINDINGS Each of the nine species of the Burkholderia cepacia complex has now received a formal species name. These names are the preferred nomenclature, replacing the former 'genomovar' designations. Studies from several countries reiterate that two species, Burkholderia cenocepacia and Burkholderia multivorans, account for most Burkholderia cepacia complex infection in cystic fibrosis. Bacterial genotyping studies indicate that specific Burkholderia cepacia complex strains infect multiple cystic fibrosis patients, implying that they may have an enhanced capacity for interpatient spread. Emerging clinical outcomes data suggest that at least some of these so-called transmissible or epidemic strains are also more virulent in the cystic fibrosis host. Ongoing research is aimed at gaining a better understanding of Burkholderia cepacia complex ecology, defining Burkholderia cepacia complex virulence factors and pathogenic mechanisms, and determining the relative virulence of distinct strains. SUMMARY Significant advances in our understanding of the Burkholderia cepacia complex serve as a critical foundation for further efforts that ultimately will enable better infection control and the development of novel therapeutics to treat Burkholderia cepacia complex infection in persons with cystic fibrosis.
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Affiliation(s)
- John J Lipuma
- Division of Infectious Diseases, Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, Michigan 48109-0646, USA.
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Walker SL. The role of nutrient presence on the adhesion kinetics of Burkholderia cepacia G4g and ENV435g. Colloids Surf B Biointerfaces 2005; 45:181-8. [PMID: 16198545 DOI: 10.1016/j.colsurfb.2005.08.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 07/12/2005] [Accepted: 08/17/2005] [Indexed: 10/25/2022]
Abstract
The adhesion kinetics of Burkholderia cepacia G4g and ENV435g have been investigated in a radial stagnation point flow (RSPF) system under well-controlled hydrodynamics and solution chemistry. The sensitivity of adhesion behavior to nutrient condition was also examined. Supplementary cell characterization techniques were conducted to evaluate the viability, hydrophobicity, electrophoretic mobility, size, and charge density of cells grown in both nutrient rich Luria broth (LB) and nutrient poor basal salts medium (BSM). Comparable adhesion kinetics were observed for the wild-type (G4g) and mutant (ENV435g) grown in the same medium; however, the attachment efficiency increased with the level of nutrient presence for both cell types by approximately 60%. Nutrient condition altered deposition due to its impact on the surface charge characteristics and size of the cells. Adhesion behavior was consistent with expectations based on classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory for colloidal interactions, as the adhesion efficiency increased with ionic strength. However, the results also suggest the involvement of non-DLVO type interactions that influence cell adhesion. Systematic experimentation with B. cepacia in the RSPF system demonstrated that the ENV435g mutant is not "adhesion deficient"; rather, adhesion for both the G4g and ENV435g was a function of the nutrient condition and resulting cell surface chemistry.
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Affiliation(s)
- Sharon L Walker
- Department of Chemical and Environmental Engineering, University of California at Riverside, Bourns Hall B355, Riverside, CA 92521, USA.
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Abstract
BACKGROUND Microbial biofilms exist all over the natural world, a distribution that is paralleled by metal cations and oxyanions. Despite this reality, very few studies have examined how biofilms withstand exposure to these toxic compounds. This article describes a batch culture technique for biofilm and planktonic cell metal susceptibility testing using the MBEC assay. This device is compatible with standard 96-well microtiter plate technology. As part of this method, a two part, metal specific neutralization protocol is summarized. This procedure minimizes residual biological toxicity arising from the carry-over of metals from challenge to recovery media. Neutralization consists of treating cultures with a chemical compound known to react with or to chelate the metal. Treated cultures are plated onto rich agar to allow metal complexes to diffuse into the recovery medium while bacteria remain on top to recover. Two difficulties associated with metal susceptibility testing were the focus of two applications of this technique. First, assays were calibrated to allow comparisons of the susceptibility of different organisms to metals. Second, the effects of exposure time and growth medium composition on the susceptibility of E. coli JM109 biofilms to metals were investigated. RESULTS This high-throughput method generated 96-statistically equivalent biofilms in a single device and thus allowed for comparative and combinatorial experiments of media, microbial strains, exposure times and metals. By adjusting growth conditions, it was possible to examine biofilms of different microorganisms that had similar cell densities. In one example, Pseudomonas aeruginosa ATCC 27853 was up to 80 times more resistant to heavy metalloid oxyanions than Escherichia coli TG1. Further, biofilms were up to 133 times more tolerant to tellurite (TeO3(2-)) than corresponding planktonic cultures. Regardless of the growth medium, the tolerance of biofilm and planktonic cell E. coli JM109 to metals was time-dependent. CONCLUSION This method results in accurate, easily reproducible comparisons between the susceptibility of planktonic cells and biofilms to metals. Further, it was possible to make direct comparisons of the ability of different microbial strains to withstand metal toxicity. The data presented here also indicate that exposure time is an important variable in metal susceptibility testing of bacteria.
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Affiliation(s)
- Joe J Harrison
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
- Biofilm Research Group, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Raymond J Turner
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
| | - Howard Ceri
- Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
- Biofilm Research Group, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
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Harrison JJ, Ceri H, Badry EA, Roper NJ, Tomlin KL, Turner RJ. Effects of the twin-arginine translocase on the structure and antimicrobial susceptibility ofEscherichia colibiofilms. Can J Microbiol 2005; 51:671-83. [PMID: 16234865 DOI: 10.1139/w05-048] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this descriptive study, we used Escherichia coli twin-arginine translocase (tat) mutants to distinguish antibiotic tolerance from the formation of mature biofilm structure. Biofilm formation by wild-type and Δtat strains of E. coli was evaluated using viable cell counts, scanning electron microscopy, and confocal laser-scanning microscopy. Escherichia coli Δtat mutants had an impaired ability to form biofilms when grown in rich or minimal media. These mutants produced disorganized layers and cell aggregates with significantly decreased cell density relative to the wild-type strain. In contrast, wild-type E. coli grown under similar test conditions formed highly structured, surface-adherent communities. We thus determined if this decreased biofilm formation by E. coli Δtat mutants may result in lowered tolerance to antimicrobials. When grown in rich media, planktonic Δtat mutants were hypersensitive to some metals, detergents, and antibiotics. However, the corresponding biofilms were about as resilient as the wild-type strain. In contrast, both planktonic cells and biofilms of the ΔtatABC strain grown in minimal media were hypersensitive to many antimicrobials. Remarkably, these biofilms remained up to 365 times more tolerant to β-lactams than corresponding planktonic cells. Our data suggest that the twin-arginine translocase may play a contributing role in the antimicrobial tolerance, structural organization, and formation of mature E. coli biofilms under nutrient-limited conditions. However, the high tolerance of the ΔtatABC strain to bactericidal concentrations of antimicrobials indicates that mature biofilm structure may not be required for surface-adherent E. coli to survive exposure to these lethal factors.Key words: biofilm structure, twin-arginine translocase (tat), Escherichia coli, antimicrobial susceptibility/tolerance.
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Affiliation(s)
- Joe J Harrison
- Department of Biological Sciences, University of Calgary, Canada
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