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De Silva LADS, Heo GJ. Biofilm formation of pathogenic bacteria isolated from aquatic animals. Arch Microbiol 2022; 205:36. [PMID: 36565346 DOI: 10.1007/s00203-022-03332-8] [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: 09/11/2021] [Revised: 11/06/2022] [Accepted: 11/10/2022] [Indexed: 12/25/2022]
Abstract
Bacterial biofilm formation is one of the dynamic processes, which facilitates bacteria cells to attach to a surface and accumulate as a colony. With the help of biofilm formation, pathogenic bacteria can survive by adapting to their external environment. These bacterial colonies have several resistance properties with a higher survival rate in the environment. Especially, pathogenic bacteria can grow as biofilms and can be protected from antimicrobial compounds and other substances. In aquaculture, biofilm formation by pathogenic bacteria has emerged with an increased infection rate in aquatic animals. Studies show that Vibrio anguillarum, V. parahaemolyticus, V. alginolyticus, V. harveyi, V. campbellii, V. fischeri, Aeromonas hydrophila, A. salmonicida, Yersinia ruckeri, Flavobacterium columnare, F. psychrophilum, Piscirickettsia salmonis, Edwardsiella tarda, E. ictaluri, E. piscicida, Streptococcus parauberis, and S. iniae can survive in the environment by transforming their planktonic form to biofilm form. Therefore, the present review was intended to highlight the principles behind biofilm formation, major biofilm-forming pathogenic bacteria found in aquaculture systems, gene expression of those bacterial biofilms and possible controlling methods. In addition, the possibility of these pathogenic bacteria can be a serious threat to aquaculture systems.
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Affiliation(s)
- L A D S De Silva
- Laboratory of Aquatic Animal Medicine, Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Chungdae-Ro 1, Seowon-Gu, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Gang-Joon Heo
- Laboratory of Aquatic Animal Medicine, Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Chungdae-Ro 1, Seowon-Gu, Cheongju, Chungbuk, 28644, Republic of Korea.
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2
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Balasubramanian D, López-Pérez M, Grant TA, Ogbunugafor CB, Almagro-Moreno S. Molecular mechanisms and drivers of pathogen emergence. Trends Microbiol 2022; 30:898-911. [DOI: 10.1016/j.tim.2022.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 02/05/2022] [Accepted: 02/10/2022] [Indexed: 12/21/2022]
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3
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Arunkumar M, LewisOscar F, Thajuddin N, Pugazhendhi A, Nithya C. In vitro and in vivo biofilm forming Vibrio spp: A significant threat in aquaculture. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.04.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Pettis GS, Mukerji AS. Structure, Function, and Regulation of the Essential Virulence Factor Capsular Polysaccharide of Vibrio vulnificus. Int J Mol Sci 2020; 21:ijms21093259. [PMID: 32380667 PMCID: PMC7247339 DOI: 10.3390/ijms21093259] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 05/01/2020] [Accepted: 05/03/2020] [Indexed: 12/23/2022] Open
Abstract
Vibrio vulnificus populates coastal waters around the world, where it exists freely or becomes concentrated in filter feeding mollusks. It also causes rapid and life-threatening sepsis and wound infections in humans. Of its many virulence factors, it is the V. vulnificus capsule, composed of capsular polysaccharide (CPS), that plays a critical role in evasion of the host innate immune system by conferring antiphagocytic ability and resistance to complement-mediated killing. CPS may also provoke a portion of the host inflammatory cytokine response to this bacterium. CPS production is biochemically and genetically diverse among strains of V. vulnificus, and the carbohydrate diversity of CPS is likely affected by horizontal gene transfer events that result in new combinations of biosynthetic genes. Phase variation between virulent encapsulated opaque colonial variants and attenuated translucent colonial variants, which have little or no CPS, is a common phenotype among strains of this species. One mechanism for generating acapsular variants likely involves homologous recombination between repeat sequences flanking the wzb phosphatase gene within the Group 1 CPS biosynthetic and transport operon. A considerable number of environmental, genetic, and regulatory factors have now been identified that affect CPS gene expression and CPS production in this pathogen.
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5
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The Peril and Promise of Integrons: Beyond Antibiotic Resistance. Trends Microbiol 2020; 28:455-464. [PMID: 31948729 DOI: 10.1016/j.tim.2019.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/13/2019] [Accepted: 12/09/2019] [Indexed: 12/11/2022]
Abstract
Integrons are bacterial genetic elements that can capture, rearrange, and express mobile gene cassettes. They are best known for their role in disseminating antibiotic-resistance genes among pathogens. Their ability to rapidly spread resistance phenotypes makes it important to consider what other integron-mediated traits might impact human health in the future, such as increased virulence, pathogenicity, or resistance to novel antimicrobial strategies. Exploring the functional diversity of cassettes and understanding their de novo creation will allow better pre-emptive management of bacterial growth, while also facilitating development of technologies that could harness integron activity. If we can control integrons and cassette formation, we could use integrons as a platform for enzyme discovery and to construct novel biochemical pathways, with applications in bioremediation or biosynthesis of industrial and therapeutic molecules. Integron activity thus holds both peril and promise for humans.
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Zeng Z, Zhan W, Wang W, Wang P, Tang K, Wang X. Biofilm formation in Pseudoalteromonas lipolytica is related to IS5-like insertions in the capsular polysaccharide operon. FEMS Microbiol Ecol 2019; 95:5488432. [PMID: 31077283 DOI: 10.1093/femsec/fiz065] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 05/10/2019] [Indexed: 11/14/2022] Open
Abstract
Bacterial capsular polysaccharides (CPSs) participate in environmental adaptation in diverse bacteria species. However, the role and regulation of CPS production in marine bacteria have remained largely unexplored. We previously reported that both wrinkled and translucent Pseudoalteromonas lipolytica variants with altered polysaccharide production were generated in pellicle biofilm-associated cells. In this study, we observed that translucent variants were generated at a rate of ∼20% in colony biofilms of P. lipolytica cultured on HSLB agar plates for 12 days. The DNA sequencing results revealed that nearly 90% of these variants had an IS5-like element inserted within the coding or promoter regions of nine genes in the cps operon. In contrast, IS5 insertion into the cps operon was not detected in planktonic cells. Furthermore, we demonstrated that the IS5 insertion event inactivated CPS production, which leads to a translucent colony morphology. The CPS-deficient variants showed an increased ability to form attached biofilms but exhibited reduced resistance to sublethal concentrations of antibiotics. Moreover, deleting the DNA repair gene recA significantly decreased the frequency of occurrence of CPS-deficient variants during biofilm formation. Thus, IS insertion into the cps operon is an important mechanism for the production of genetic variants during biofilm formation of marine bacteria.
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Affiliation(s)
- Zhenshun Zeng
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Waner Zhan
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weiquan Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pengxia Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
| | - Kaihao Tang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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Ghaly TM, Geoghegan JL, Alroy J, Gillings MR. High diversity and rapid spatial turnover of integron gene cassettes in soil. Environ Microbiol 2019; 21:1567-1574. [PMID: 30724441 DOI: 10.1111/1462-2920.14551] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 01/30/2019] [Indexed: 12/01/2022]
Abstract
Integrons are genetic elements that promote rapid adaptation in bacteria by capturing exogenous, mobile gene cassettes. Recently, a subset of gene cassettes has facilitated the global spread of antibiotic resistance. However, outside clinical settings, very little is known about their diversity and spatial ecology. To address this question, we sequenced integron gene cassettes from soils sampled across Australia and Antarctica. We recovered 44 970 open reading frames that encoded 27 215 unique proteins, representing an order of magnitude more cassettes than previous sequencing efforts. We found that cassettes have extremely high local richness, significantly greater than previously predicted, with estimates ranging from 4000 to 18 000 unique cassettes per 0.3 g of soil. We show that cassettes have a heterogeneous distribution across space, and that they exhibit rapid turnover with distance. Similarity between samples drops to between 0.1% and 10% at distances of as little as 100 m. Together, these data provide key insights into the ecology and size of the gene cassette metagenome.
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Affiliation(s)
- Timothy M Ghaly
- Department of Biological Science, Macquarie University, Sydney, NSW, 2109, Australia
| | - Jemma L Geoghegan
- Department of Biological Science, Macquarie University, Sydney, NSW, 2109, Australia
| | - John Alroy
- Department of Biological Science, Macquarie University, Sydney, NSW, 2109, Australia
| | - Michael R Gillings
- Department of Biological Science, Macquarie University, Sydney, NSW, 2109, Australia
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Elgaml A, Miyoshi SI. Regulation systems of protease and hemolysin production inVibrio vulnificus. Microbiol Immunol 2017; 61:1-11. [DOI: 10.1111/1348-0421.12465] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/19/2016] [Accepted: 01/16/2017] [Indexed: 11/29/2022]
Affiliation(s)
- Abdelaziz Elgaml
- Microbiology and Immunology Department; Faculty of Pharmacy; Mansoura University; Elgomhouria Street Mansoura 35516 Egypt
| | - Shin-Ichi Miyoshi
- Graduate School of Medicine; Dentistry and Pharmaceutical Sciences; Okayama University; 1-1-1 Tsushima-Naka Kita-Ku Okayama 700-8530 Japan
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Genetic and Molecular Basis of Kingella kingae Encapsulation. Infect Immun 2016; 84:1775-1784. [PMID: 27045037 DOI: 10.1128/iai.00128-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Accepted: 03/28/2016] [Indexed: 12/30/2022] Open
Abstract
Kingella kingae is a common cause of invasive disease in young children and was recently found to produce a polysaccharide capsule containing N-acetylgalactosamine (GalNAc) and β-3-deoxy-d-manno-octulosonic acid (βKdo). Given the role of capsules as important virulence factors and effective vaccine antigens, we set out to determine the genetic determinants of K. kingae encapsulation. Using a transposon library and a screen for nonencapsulated mutants, we identified the previously identified ctrABCD (ABC transporter) operon, a lipA (kpsC)-like gene, a lipB (kpsS)-like gene, and a putative glycosyltransferase gene designated csaA (capsule synthesis type a gene A). These genes were found to be present at unlinked locations scattered throughout the genome, an atypical genetic arrangement for Gram-negative bacteria that elaborate a capsule dependent on an ABC-type transporter for surface localization. The csaA gene product contains a predicted glycosyltransferase domain with structural homology to GalNAc transferases and a predicted capsule synthesis domain with structural homology to Kdo transferases, raising the possibility that this enzyme is responsible for alternately linking GalNAc to βKdo and βKdo to GalNAc. Consistent with this conclusion, mutation of the DXD motif in the GalNAc transferase domain and of the HP motif in the Kdo transferase domain resulted in a loss of encapsulation. Examination of intracellular and surface-associated capsule in deletion mutants and complemented strains further implicated the lipA (kpsC)-like gene, the lipB (kpsS)-like gene, and the csaA gene in K. kingae capsule production. These data define the genetic requirements for encapsulation in K. kingae and demonstrate an atypical organization of capsule synthesis, assembly, and export genes.
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Silveira DR, Milan C, Rosa JVD, Timm CD. Fatores de patogenicidade de Vibrio spp. de importância em doenças transmitidas por alimentos. ARQUIVOS DO INSTITUTO BIOLÓGICO 2016. [DOI: 10.1590/1808-1657001252013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
RESUMO: As bactérias do gênero Vibrio habitam ambiente tipicamente marinho e estuarino, sendo comumente isoladas de pescados. As principais espécies de Vibrio reportadas como agentes de infecções em humanos são V. vulnificus , V. parahaemolyticus , V. cholerae e V. mimicus . V. vulnificus é considerado o mais perigoso, podendo causar septicemia e levar à morte. V. parahaemolyticus é um patógeno importante nas regiões costeiras de clima temperado e tropical em todo o mundo e tem sido responsável por casos de gastroenterites associadas ao consumo de peixes, moluscos e crustáceos marinhos. V. cholerae causa surtos, epidemias e pandemias relacionados com ambientes estuarinos. V. mimicus pode causar episódios esporádicos de gastroenterite aguda e infecções de ouvido. A patogenicidade das bactérias está ligada à habilidade do micro-organismo em iniciar uma doença (incluindo entrada, colonização e multiplicação no corpo humano). Para que isso ocorra, os micro-organismos fazem uso de diversos fatores. O objetivo desta revisão foi sintetizar o conhecimento disponível na literatura sobre os fatores de patogenicidade de V. vulnificus , V. parahaemolyticus , V. cholerae e V. mimicus .
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Abstract
Integrons are versatile gene acquisition systems commonly found in bacterial genomes. They are ancient elements that are a hot spot for genomic complexity, generating phenotypic diversity and shaping adaptive responses. In recent times, they have had a major role in the acquisition, expression, and dissemination of antibiotic resistance genes. Assessing the ongoing threats posed by integrons requires an understanding of their origins and evolutionary history. This review examines the functions and activities of integrons before the antibiotic era. It shows how antibiotic use selected particular integrons from among the environmental pool of these elements, such that integrons carrying resistance genes are now present in the majority of Gram-negative pathogens. Finally, it examines the potential consequences of widespread pollution with the novel integrons that have been assembled via the agency of human antibiotic use and speculates on the potential uses of integrons as platforms for biotechnology.
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Jackson RW, Vinatzer B, Arnold DL, Dorus S, Murillo J. The influence of the accessory genome on bacterial pathogen evolution. Mob Genet Elements 2014; 1:55-65. [PMID: 22016845 DOI: 10.4161/mge.1.1.16432] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/09/2011] [Accepted: 05/10/2011] [Indexed: 01/15/2023] Open
Abstract
Bacterial pathogens exhibit significant variation in their genomic content of virulence factors. This reflects the abundance of strategies pathogens evolved to infect host organisms by suppressing host immunity. Molecular arms-races have been a strong driving force for the evolution of pathogenicity, with pathogens often encoding overlapping or redundant functions, such as type III protein secretion effectors and hosts encoding ever more sophisticated immune systems. The pathogens' frequent exposure to other microbes, either in their host or in the environment, provides opportunities for the acquisition or interchange of mobile genetic elements. These DNA elements accessorize the core genome and can play major roles in shaping genome structure and altering the complement of virulence factors. Here, we review the different mobile genetic elements focusing on the more recent discoveries and highlighting their role in shaping bacterial pathogen evolution.
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Affiliation(s)
- Robert W Jackson
- School of Biological Sciences; University of Reading; Whiteknights; Reading, UK
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Garrison-Schilling KL, Kaluskar ZM, Lambert B, Pettis GS. Genetic analysis and prevalence studies of the brp exopolysaccharide locus of Vibrio vulnificus. PLoS One 2014; 9:e100890. [PMID: 25013926 PMCID: PMC4094392 DOI: 10.1371/journal.pone.0100890] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 06/02/2014] [Indexed: 11/19/2022] Open
Abstract
Phase variation in the Gram-negative human pathogen Vibrio vulnificus involves three colonial morphotypes- smooth opaque colonies due to production of capsular polysaccharide (CPS), smooth translucent colonies as the result of little or no CPS expression, and rugose colonies due to production of a separate extracellular polysaccharide (EPS), which greatly enhances biofilm formation. Previously, it was shown that the brp locus, which consists of nine genes arranged as an operon, is up-regulated in rugose strains in a c-di-GMP-dependent manner, and that plasmid insertions into the locus resulted in loss of rugosity and efficient biofilm production. Here, we have used non-polar mutagenesis to assess the involvement of individual brp genes in production of EPS and related phenotypes. Inactivation of genes predicted to be involved in various stages of EPS biosynthesis eliminated both the rugose colonial appearance and production of EPS, while knockout of a predicted flippase function involved in EPS transport resulted in a dry, lightly striated phenotype, which was associated with a reduction of brp-encoded EPS on the cell surface. All brp mutants retained the reduced motility characteristic of rugose strains. Lastly, we provide evidence that the brp locus is highly prevalent among strains of V. vulnificus.
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Affiliation(s)
| | - Zelam M. Kaluskar
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Bliss Lambert
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Gregg S. Pettis
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
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Rapa RA, Labbate M. The function of integron-associated gene cassettes in Vibrio species: the tip of the iceberg. Front Microbiol 2013; 4:385. [PMID: 24367362 PMCID: PMC3856429 DOI: 10.3389/fmicb.2013.00385] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/25/2013] [Indexed: 12/17/2022] Open
Abstract
The integron is a genetic element that incorporates mobile genes termed gene cassettes into a reserved genetic site via site-specific recombination. It is best known for its role in antibiotic resistance with one type of integron, the class 1 integron, a major player in the dissemination of antibiotic resistance genes across Gram negative pathogens and commensals. However, integrons are ancient structures with over 100 classes (including class 1) present in bacteria from the broader environment. While, the class 1 integron is only one example of an integron being mobilized into the clinical environment, it is by far the most successful. Unlike clinical class 1 integrons which are largely found on plasmids, other integron classes are found on the chromosomes of bacteria and carry diverse gene cassettes indicating a non-antibiotic resistance role(s). However, there is very limited knowledge on what these alternative roles are. This is particularly relevant to Vibrio species where gene cassettes make up approximately 1-3% of their entire genome. In this review, we discuss how emphasis on class 1 integron research has resulted in a limited understanding by the wider research community on the role of integrons in the broader environment. This has the capacity to be counterproductive in solving or improving the antibiotic resistance problem into the future. Furthermore, there is still a significant lack of knowledge on how gene cassettes in Vibrio species drive adaptation and evolution. From research in Vibrio rotiferianus DAT722, new insight into how gene cassettes affect cellular physiology offers new alternative roles for the gene cassette resource. At least a subset of gene cassettes are involved in host surface polysaccharide modification suggesting that gene cassettes may be important in processes such as bacteriophage resistance, adhesion/biofilm formation, protection from grazers and bacterial aggregation.
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Affiliation(s)
- Rita A Rapa
- ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia
| | - Maurizio Labbate
- ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia
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Rapa RA, Shimmon R, Djordjevic SP, Stokes HW, Labbate M. Deletion of integron-associated gene cassettes impact on the surface properties of Vibrio rotiferianus DAT722. PLoS One 2013; 8:e58430. [PMID: 23484028 PMCID: PMC3590141 DOI: 10.1371/journal.pone.0058430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 02/06/2013] [Indexed: 01/21/2023] Open
Abstract
Background The integron is a genetic recombination system that catalyses the acquisition of genes on mobilisable elements called gene cassettes. In Vibrio species, multiple acquired gene cassettes form a cassette array that can comprise 1–3% of the bacterial genome. Since 75% of these gene cassettes contain genes encoding proteins of uncharacterised function, how the integron has driven adaptation and evolution in Vibrio species remains largely unknown. A feature of cassette arrays is the presence of large indels. Using Vibrio rotiferianus DAT722 as a model organism, the aim of this study was to determine how large cassette deletions affect vibrio physiology with a view to improving understanding into how cassette arrays influence bacterial host adaptation and evolution. Methodology/Principal Findings Biological assays and proteomic techniques were utilised to determine how artificially engineered deletions in the cassette array of V. rotiferianus DAT722 affected cell physiology. Multiple phenotypes were identified including changes to growth and expression of outer membrane porins/proteins and metabolic proteins. Furthermore, the deletions altered cell surface polysaccharide with Proton Nuclear Magnetic Resonance on whole cell polysaccharide identifying changes in the carbohydrate ring proton region indicating that gene cassette products may decorate host cell polysaccharide via the addition or removal of functional groups. Conclusions/Significance From this study, it was concluded that deletion of gene cassettes had a subtle effect on bacterial metabolism but altered host surface polysaccharide. Deletion (and most likely rearrangement and acquisition) of gene cassettes may provide the bacterium with a mechanism to alter its surface properties, thus impacting on phenotypes such as biofilm formation. Biofilm formation was shown to be altered in one of the deletion mutants used in this study. Reworking surface properties may provide an advantage to the bacterium’s interactions with organisms such as bacteriophage, protozoan grazers or crustaceans.
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Affiliation(s)
- Rita A. Rapa
- The ithree Institute, University of Technology, Sydney, Australia
| | - Ronald Shimmon
- Chemical Technology and Forensic Science, University of Technology, Sydney, Australia
| | | | - H. W. Stokes
- The ithree Institute, University of Technology, Sydney, Australia
| | - Maurizio Labbate
- The ithree Institute, University of Technology, Sydney, Australia
- * E-mail:
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Liu M, Crosa JH. The regulator HlyU, the repeat-in-toxin gene rtxA1, and their roles in the pathogenesis of Vibrio vulnificus infections. Microbiologyopen 2012; 1:502-13. [PMID: 23233275 PMCID: PMC3535394 DOI: 10.1002/mbo3.48] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/27/2012] [Accepted: 08/06/2012] [Indexed: 12/19/2022] Open
Abstract
HlyU is a master regulator that plays an essential role in the virulence of the human pathogen Vibrio vulnificus. One of the most noteworthy characteristics of HlyU regulation in this organism is its positive control of the expression of the repeat-in-toxin (RtxA1) gene, one of the most important virulence factors accounting for the fulminating and damaging nature of V. vulnificus infections. In this work, we reviewed the latest studies of RtxA1 in this bacterium and highlight the mechanism of gene regulation of rtxA1 expression by HlyU under a broader gene regulatory network.
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Affiliation(s)
- Moqing Liu
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, Oregon 97239, USA.
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Huff K, Aroonnual A, Littlejohn AEF, Rajwa B, Bae E, Banada PP, Patsekin V, Hirleman ED, Robinson JP, Richards GP, Bhunia AK. Light-scattering sensor for real-time identification of Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae colonies on solid agar plate. Microb Biotechnol 2012; 5:607-20. [PMID: 22613192 PMCID: PMC3815873 DOI: 10.1111/j.1751-7915.2012.00349.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 04/11/2012] [Indexed: 12/17/2022] Open
Abstract
The three most common pathogenic species of Vibrio, Vibrio cholerae, Vibrio parahaemolyticus and Vibrio vulnificus, are of major concerns due to increased incidence of water‐ and seafood‐related outbreaks and illness worldwide. Current methods are lengthy and require biochemical and molecular confirmation. A novel label‐free forward light‐scattering sensor was developed to detect and identify colonies of these three pathogens in real time in the presence of other vibrios in food or water samples. Vibrio colonies grown on agar plates were illuminated by a 635 nm laser beam and scatter‐image signatures were acquired using a CCD (charge‐coupled device) camera in an automated BARDOT (BActerial Rapid Detection using Optical light‐scattering Technology) system. Although a limited number of Vibrio species was tested, each produced a unique light‐scattering signature that is consistent from colony to colony. Subsequently a pattern recognition system analysing the collected light‐scatter information provided classification in 1−2 min with an accuracy of 99%. The light‐scattering signatures were unaffected by subjecting the bacteria to physiological stressors: osmotic imbalance, acid, heat and recovery from a viable but non‐culturable state. Furthermore, employing a standard sample enrichment in alkaline peptone water for 6 h followed by plating on selective thiosulphate citrate bile salts sucrose agar at 30°C for ∼ 12 h, the light‐scattering sensor successfully detected V. cholerae, V. parahaemolyticus and V. vulnificus present in oyster or water samples in 18 h even in the presence of other vibrios or other bacteria, indicating the suitability of the sensor as a powerful screening tool for pathogens on agar plates.
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Affiliation(s)
- Karleigh Huff
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN, USA
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Datta S, Crosa JH. Identification and characterization of a novel outer membrane protein receptor required for hemin utilization in Vibrio vulnificus. Biometals 2011; 25:275-83. [PMID: 22015545 DOI: 10.1007/s10534-011-9501-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 10/11/2011] [Indexed: 12/19/2022]
Abstract
Vibrio vulnificus, the cause of septicemia and serious wound infection in humans and fishes, require iron for its pathogenesis. Hemin uptake through the outer membrane receptor, HupA, is one of its many mechanisms by which it acquires iron. We report here the identification of an additional TonB-dependent hemin receptor HvtA, that is needed in conjunction with the HupA protein for optimal hemin utilization. The HvtA protein is significantly homologous to other outer membrane hemin receptors and its expression in trans restored the uptake of hemin and hemoglobin, the latter to a weaker extent, in a mutant strain that was defective in both receptors. Quantitative RT-PCR suggested that transcription of the hvtA gene was iron regulated. The operon containing the hvtA gene is homologous to the operon in V. cholerae containing the hemin receptor gene hutR suggesting a vertical transmission of the hvtA cluster from V. cholerae to V. vulnificus.
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Affiliation(s)
- Shreya Datta
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, USA
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Affiliation(s)
- Guillaume Cambray,
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
| | - Anne-Marie Guerout,
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
| | - Didier Mazel
- Institut Pasteur, Unité Plasticité du Génome Bactérien, Département Génomes et Génétique, F-75015 Paris, France;
- CNRS, URA2171, F-75015 Paris, France
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Garrison-Schilling KL, Grau BL, McCarter KS, Olivier BJ, Comeaux NE, Pettis GS. Calcium promotes exopolysaccharide phase variation and biofilm formation of the resulting phase variants in the human pathogen Vibrio vulnificus. Environ Microbiol 2010; 13:643-54. [DOI: 10.1111/j.1462-2920.2010.02369.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Liu M, Naka H, Crosa JH. HlyU acts as an H-NS antirepressor in the regulation of the RTX toxin gene essential for the virulence of the human pathogen Vibrio vulnificus CMCP6. Mol Microbiol 2009; 72:491-505. [PMID: 19320834 DOI: 10.1111/j.1365-2958.2009.06664.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In Vibrio vulnificus, HlyU upregulates the expression of the large RTX toxin gene. In this work we identified the binding site of HlyU to -417 to -376 bp of the rtxA1 operon transcription start site. lacZ fusions for a series of progressive deletions from the rtxA1 operon promoter showed that transcriptional activity increased independently of HlyU when its binding site was absent. Thus HlyU must regulate the rtxA1 operon expression by antagonizing a negative regulator. Concomitantly we found that an hns mutant resulted in an increase in the expression of the rtxA1 operon genes. Multiple copies of HlyU can increase the promoter activity only in the presence of H-NS underscoring the hypothesis that HlyU must alleviate the repression by this protein. H-NS binds to a region that extends upstream and downstream of the rtxA1 operon promoter. In the upstream region it binds to five AT-rich sites of which two overlap the HlyU binding site. Competitive footprinting and gel shift data demonstrate HlyU's higher affinity as compared with H-NS resulting in the de-repression and a corresponding increased expression of the rtxA1 operon.
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Affiliation(s)
- Moqing Liu
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, USA
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23
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Vibrio biofilms: so much the same yet so different. Trends Microbiol 2009; 17:109-18. [PMID: 19231189 DOI: 10.1016/j.tim.2008.12.004] [Citation(s) in RCA: 314] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 11/11/2008] [Accepted: 12/05/2008] [Indexed: 12/20/2022]
Abstract
Vibrios are natural inhabitants of aquatic environments and form symbiotic or pathogenic relationships with eukaryotic hosts. Recent studies reveal that the ability of vibrios to form biofilms (i.e. matrix-enclosed, surface-associated communities) depends upon specific structural genes (flagella, pili and exopolysaccharide biosynthesis) and regulatory processes (two-component regulators, quorum sensing and c-di-GMP signaling). Here, we compare and contrast mechanisms and regulation of biofilm formation by Vibrio species, with a focus on Vibrio cholerae, Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio fischeri. Although many aspects are the same, others differ dramatically. Crucial questions that remain to be answered regarding the molecular underpinnings of Vibrio biofilm formation are also discussed.
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Molecular analysis of the Enterobacter sakazakii O-antigen gene locus. Appl Environ Microbiol 2008; 74:3783-94. [PMID: 18441119 DOI: 10.1128/aem.02302-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nucleotide polymorphism associated with the O-antigen-encoding locus, rfb, in Enterobacter sakazakii was determined by PCR-restriction fragment length polymorphism analysis. Based on the analysis of these DNA profiles, 12 unique banding patterns were detected among a collection of 62 strains from diverse origins. Two common profiles were identified and were designated serotypes O:1 and O:2. DNA sequencing of the 12,500-bp region flanked by galF and gnd identified 11 open reading frames, all with the same transcriptional direction. Analysis of the proximal region of both sequences demonstrated remarkable heterogeneity. A PCR assay targeting genes specific for the two prominent serotypes was developed and applied for the identification of these strains recovered from food, environmental, and clinical samples.
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Further characterization of Vibrio vulnificus rugose variants and identification of a capsular and rugose exopolysaccharide gene cluster. Infect Immun 2008; 76:1485-97. [PMID: 18212074 DOI: 10.1128/iai.01289-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Capsular polysaccharide (CPS) is a major virulence factor in Vibrio vulnificus, and encapsulated strains have an opaque, smooth (OpS) colony morphology, while nonencapsulated strains have a translucent, smooth (TrS) colony morphology. Previously, we showed that OpS and TrS parental strains can yield a third colony type, rugose (R), and that the resulting strains, with the OpR and TrR phenotypes, respectively, form copious biofilms. Here we show that while OpR and TrR strains both produce three-dimensional biofilm structures that are indicative of rugose extracellular polysaccharide (rEPS) production, OpR strains also retain expression of CPS and are virulent in an iron-supplemented mouse model, while TrR strains lack CPS and are avirulent. Chlorine resistance assays further distinguished OpR and TrR isolates as exposure to 3 microg/ml NaOCl eradicated both OpS and OpR strains, while both TrS and TrR strains survived, but at rates which were significantly different from one another. Taken together, these results further emphasize the importance of CPS for virulence of V. vulnificus and establish a correlation between CPS expression and chlorine sensitivity in this organism. Using reverse transcriptase PCR, we also identified a nine-gene cluster associated with both CPS and rEPS expression in V. vulnificus, designated the wcr (capsular and rugose polysaccharide) locus, with expression occurring primarily in R variants. The latter results set the stage for characterization of functional determinants which individually or collectively contribute to expression of multiple EPS forms in this pathogen.
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Detection and characterization of a functional insertion sequence, ISVpa2, in Vibrio parahaemolyticus. Gene 2007; 409:92-9. [PMID: 18164873 DOI: 10.1016/j.gene.2007.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 11/20/2007] [Accepted: 11/27/2007] [Indexed: 11/22/2022]
Abstract
PCR analysis of the pandemic strain of Vibrio parahaemolyticus, KX-V237 (total genome sequenced) showed a subculture where the size of the amplicons had increased. The purpose of this study was to analyze the mechanism of this change. We found a 1,243-bp DNA sequence inserted in one of the pandemic marker genes in this strain. The inserted DNA sequence possessed the genetic structures shared by insertion sequences (ISs) of the IS3 family. This IS had 26-bp imperfect terminal inverted repeats (IRs) and two partially overlapping reading frames, orfA and orfB. OrfA codes for a helix-turn-helix, OrfA and OrfAB produced by translational frameshifting code for leucine zipper motifs, and OrfB codes for a DDE motif. orfA and orfB were homologous to those in the IS3 family. This IS was named ISVpa2. Southern blot analysis showed the copy number of ISVpa2 in our stock culture and its subculture of KX-V237 was three and four, respectively; whereas it was only one in the reported genome sequence. Analysis of the flanking sequences for seven ISVpa2 copies showed ISVpa2 is capable of inserting at multiple sites and ISVpa2 causes genetic rearrangements including insertional inactivation of the target gene and adjacent deletion. ISVpa2 created 3-base duplications upon insertion. PCR, hybridization, and nucleotide sequence analyses showed ISVpa2 homologs were detected in all of the 62 other strains of V. parahaemolyticus examined; and in some strains of Vibrio vulnificus (98% identity), Vibrio penaeicida (86% identity), and Vibrio splendidus (87% identity); but was not in 25 other species in the genus Vibrio. The data demonstrate that ISVpa2 is a transpositionally active IS discovered for the first time in V. parahaemolyticus and suggest that ISVpa2 may be transferred among the species of the genus Vibrio.
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Identification of a Wzy polymerase required for group IV capsular polysaccharide and lipopolysaccharide biosynthesis in Vibrio vulnificus. Infect Immun 2007; 75:5550-8. [PMID: 17923517 DOI: 10.1128/iai.00932-07] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The estuarine bacterium Vibrio vulnificus is a human and animal pathogen. The expression of capsular polysaccharide (CPS) is essential for virulence. We used a new mini-Tn10 delivery vector, pNKTXI-SceI, to generate a mutant library and identify genes essential for CPS biosynthesis. Twenty-one acapsular mutants were isolated, and the disrupted gene in one mutant, coding for a polysaccharide polymerase (wzy), is described here. A wecA gene initiating glycosyltransferase was among the genes identified in the region flanking the wzy gene. This, together with the known structure of the CPS, supports a group IV capsule designation for the locus; however, its overall organization mirrored that of group I capsules. This new arrangement may be linked to our finding that the CPS region appears to have been recently acquired by horizontal transfer. Alcian Blue staining and immunoblotting with antisera against the wild-type strain indicated that the wzy::Tn10 mutant failed to produce CPS and was attenuated relative to the wild type in a septicemic mouse model. Interestingly, immunoblotting revealed that the mutant was also defective in lipopolysaccharide (LPS) production. However, the core-plus-one O-antigen pattern typical of wzy mutations was apparent. CPS production, LPS production, and virulence were restored following complementation with the wild-type wzy gene. Hence, Wzy participates in both CPS and LPS biosynthesis and is required for virulence in strain 27562. To our knowledge, this is the first functional demonstration of a Wzy polysaccharide polymerase in V. vulnificus and is the first to show a link between LPS and CPS biosynthesis.
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Boucher Y, Labbate M, Koenig JE, Stokes HW. Integrons: mobilizable platforms that promote genetic diversity in bacteria. Trends Microbiol 2007; 15:301-9. [PMID: 17566739 DOI: 10.1016/j.tim.2007.05.004] [Citation(s) in RCA: 205] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 04/13/2007] [Accepted: 05/25/2007] [Indexed: 10/23/2022]
Abstract
Integrons facilitate the capture of potentially adaptive exogenous genetic material by their host genomes. It is now clear that integrons are not limited to the clinical contexts in which they were originally discovered because approximately 10% of bacterial genomes that have been partially or completely sequenced harbour this genetic element. This wealth of sequence information has revealed that integrons are not only much more phylogenetically diverse than previously thought but also more mobilizable, with many integrons having been subjected to frequent lateral gene transfer throughout their evolutionary history. This indicates that the genetic characteristics that make integrons such efficient vectors for the spread of antibiotic resistance genes have been associated with these elements since their earliest origins. Here, we give an overview of the structural and phylogenetic diversity of integrons and describe evolutionary events that have contributed to the success of these genetic elements.
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Affiliation(s)
- Yan Boucher
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
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Liu M, Alice AF, Naka H, Crosa JH. The HlyU protein is a positive regulator of rtxA1, a gene responsible for cytotoxicity and virulence in the human pathogen Vibrio vulnificus. Infect Immun 2007; 75:3282-9. [PMID: 17438022 PMCID: PMC1932941 DOI: 10.1128/iai.00045-07] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio vulnificus is an opportunistic human pathogen that preferentially infects compromised iron-overloaded patients, causing a fatal primary septicemia with very rapid progress, resulting in a high mortality rate. In this study we determined that the HlyU protein, a virulence factor in V. vulnificus CMCP6, up-regulates the expression of VV20479, a homologue of the Vibrio cholerae RTX (repeats in toxin) toxin gene that we named rtxA1. This gene is part of an operon together with two other open reading frames, VV20481 and VV20480, that encode two predicted proteins, a peptide chain release factor 1 and a hemolysin acyltransferase, respectively. A mutation in rtxA1 not only contributes to the loss of cytotoxic activity but also results in a decrease in virulence, whereas a deletion of VV20481 and VV20480 causes a slight decrease in virulence but with no effect in cytotoxicity. Activation of the expression of the rtxA1 operon by HlyU occurs at the transcription initiation level by binding of the HlyU protein to a region upstream of this operon.
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Affiliation(s)
- Moqing Liu
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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The capsule polysaccharide structure and biogenesis for non-O1 Vibrio cholerae NRT36S: genes are embedded in the LPS region. BMC Microbiol 2007; 7:20. [PMID: 17362509 PMCID: PMC1847822 DOI: 10.1186/1471-2180-7-20] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 03/15/2007] [Indexed: 12/01/2022] Open
Abstract
Background In V. cholerae, the biogenesis of capsule polysaccharide is poorly understood. The elucidation of capsule structure and biogenesis is critical to understanding the evolution of surface polysaccharide and the internal relationship between the capsule and LPS in this species. V. cholerae serogroup O31 NRT36S, a human pathogen that produces a heat-stable enterotoxin (NAG-ST), is encapsulated. Here, we report the covalent structure and studies of the biogenesis of the capsule in V. cholerae NRT36S. Results The structure of the capsular (CPS) polysaccharide was determined by high resolution NMR spectroscopy and shown to be a complex structure with four residues in the repeating subunit. The gene cluster of capsule biogenesis was identified by transposon mutagenesis combined with whole genome sequencing data (GenBank accession DQ915177). The capsule gene cluster shared the same genetic locus as that of the O-antigen of lipopolysaccharide (LPS) biogenesis gene cluster. Other than V. cholerae O139, this is the first V. cholerae CPS for which a structure has been fully elucidated and the genetic locus responsible for biosynthesis identified. Conclusion The co-location of CPS and LPS biosynthesis genes was unexpected, and would provide a mechanism for simultaneous emergence of new O and K antigens in a single strain. This, in turn, may be a key element for V. cholerae to evolve new strains that can escape immunologic detection by host populations.
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Bisharat N, Amaro C, Fouz B, Llorens A, Cohen DI. Serological and molecular characteristics of Vibrio vulnificus biotype 3: evidence for high clonality. Microbiology (Reading) 2007; 153:847-856. [PMID: 17322205 DOI: 10.1099/mic.0.2006/003723-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vibrio vulnificus biotype 3 has been implicated as the causative pathogen of an ongoing disease outbreak that erupted in Israel in 1996. Recent work based on multi-locus sequence typing (MLST) showed that V. vulnificus biotype 3 is genetically homogeneous. The aim of this study was to investigate the existence of subpopulations within this homogeneous biotype by characterizing the surface antigens and analysing the sequence diversity of selected outer-membrane protein (OMP)-encoding genes. Rabbit antisera were prepared against biotype 1, 2 and 3 strains. The results of the slide-agglutination test, dot-blot assay (using fresh and boiled cells), and immunoblotting of lipopolysaccharides (LPS) and OMPs were evaluated. By slide-agglutination and dot-blot assays all biotype 3 strains agglutinated with the selected biotype 3 strain. This homogeneity was supported by immunoblot analysis of the LPS. Analysis of OMP patterns revealed that all three biotypes share a considerable number of common bands that are antigenically related. Cluster analysis of DNA sequence data from selected OMP-encoding genes showed that biotype 3 strains form a genetically distinct and homogeneous clone. The homogeneity of surface antigens and the lack of any sequence diversity among both housekeeping and OMP-encoding genes reaffirms the highly clonal nature of biotype 3 and suggests that it has only recently descended from the parent population of V. vulnificus.
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Affiliation(s)
- Naiel Bisharat
- Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Carmen Amaro
- Departamento de Microbiologia y Ecologia, Campus de Burjassot, Universidad de Valencia, Valencia 46100, Spain
| | - Belén Fouz
- Departamento de Microbiologia y Ecologia, Campus de Burjassot, Universidad de Valencia, Valencia 46100, Spain
| | - Amparo Llorens
- Departamento de Microbiologia y Ecologia, Campus de Burjassot, Universidad de Valencia, Valencia 46100, Spain
| | - Daniel I Cohen
- Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
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Rosche TM, Smith B, Oliver JD. Evidence for an intermediate colony morphology of Vibrio vulnificus. Appl Environ Microbiol 2006; 72:4356-9. [PMID: 16751551 PMCID: PMC1489594 DOI: 10.1128/aem.02937-05] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio vulnificus causes both food-borne disease and wound infections. Most V. vulnificus strains express capsular polysaccharide (CPS), which is required for the virulence of this organism. Under standard growth conditions, CPS expression is lost at a relatively high frequency (10(-3) to 10(-4)), resulting in a switch from an opaque (Op, CPS+) colony morphology to a translucent (Tr, CPS-) colony morphology. The wzb gene, which encodes a phosphatase required for CPS expression, has been proposed to be involved in this switch through a site-specific deletion of the entire gene. In an examination of five strains, we found that the frequency of wzb deletion in Tr colonies varies by strain and therefore does not account for all the Tr colonies that are seen. In addition, we have identified a third, intermediate (Int) colony morphotype, in which the colonies appear less opaque but are not fully translucent. PCR studies have demonstrated that Int colonies still contain the wzb gene, while reverse transcriptase PCR studies have shown that although Int strains retain expression of wzb, in some cases the transcription of wzb is reduced. Int strains switch to a true Tr (wzb negative) morphotype at a very high frequency (nearly 100%) under certain conditions. Finally, Int colonies, which in some cases can easily be mistaken for Tr colonies, have been observed to occasionally revert to Op, while Tr colonies containing a wzb deletion presumably are unable to revert to the encapsulated form.
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Affiliation(s)
- Thomas M Rosche
- Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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Hilton T, Rosche T, Froelich B, Smith B, Oliver J. Capsular polysaccharide phase variation in Vibrio vulnificus. Appl Environ Microbiol 2006; 72:6986-93. [PMID: 16936057 PMCID: PMC1636181 DOI: 10.1128/aem.00544-06] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Commonly found in raw oysters, Vibrio vulnificus poses a serious health threat to immunocompromised individuals and those with serum iron overload, with a fatality rate of approximately 50%. An essential virulence factor is its capsular polysaccharide (CPS), which is responsible for a significant increase in virulence compared to nonencapsulated strains. However, this bacterium is known to vary the amount of CPS expressed on the cell surface, converting from an opaque (Op) colony phenotype to a translucent (Tr) colony phenotype. In this study, the consistency of CPS conversion was determined for four strains of V. vulnificus. Environmental conditions including variations in aeration, temperature, incubation time, oxidative stress, and media (heart infusion or modified maintenance medium agar) were investigated to determine their influence on CPS conversion. All conditions, with the exception of variations in media and oxidative stress, significantly affected the conversion of the population, with high ranges of CPS expression found even within cells from a single colony. The global quorum-sensing regulators RpoS and AI-2 were also examined. While RpoS was found to significantly mediate phenotypic conversion, quorum sensing was not. Finally, 12 strains that comprise the recently found clinical (C) and environmental (E) genotypes of V. vulnificus were examined to determine their rates of population conversion. C-genotype strains, which are most often associated with infection, had a significantly lower rate of population conversion from Op to Tr phenotypes than did E-genotype strains (ca. 38% versus ca. 14%, respectively). Biofilm capabilities of these strains, however, were not correlated with increased population conversion.
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Affiliation(s)
- Tamara Hilton
- University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223
| | - Tom Rosche
- University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223
| | - Brett Froelich
- University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223
| | - Benjamin Smith
- University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223
| | - James Oliver
- University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, North Carolina 28223
- Corresponding author. Mailing address: University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223. Phone: (704) 687-8516. Fax: (704) 687-3457. E-mail:
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Abstract
Integrons are assembly platforms - DNA elements that acquire open reading frames embedded in exogenous gene cassettes and convert them to functional genes by ensuring their correct expression. They were first identified by virtue of their important role in the spread of antibiotic-resistance genes. More recently, our understanding of their importance in bacterial genome evolution has broadened with the discovery of larger integron structures, termed superintegrons. These DNA elements contain hundreds of accessory genes and constitute a significant fraction of the genomes of many bacterial species. Here, the basic biology of integrons and superintegrons, their evolutionary history and the evidence for the existence of a novel recombination pathway is reviewed.
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Affiliation(s)
- Didier Mazel
- Unité Plasticité du Génome Bactérien- CNRS URA 2171, Department Génomes et Génétique, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris, France.
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Chatzidaki-Livanis M, Jones MK, Wright AC. Genetic variation in the Vibrio vulnificus group 1 capsular polysaccharide operon. J Bacteriol 2006; 188:1987-98. [PMID: 16484211 PMCID: PMC1426558 DOI: 10.1128/jb.188.5.1987-1998.2006] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio vulnificus produces human disease associated with raw-oyster consumption or wound infections, but fatalities are limited to persons with chronic underlying illness. Capsular polysaccharide (CPS) is required for virulence, and CPS expression correlates with opaque (Op) colonies that show "phase variation" to avirulent translucent (Tr) phenotypes with reduced CPS. The results discussed here confirmed homology of a V. vulnificus CPS locus to the group 1 CPS operon in Escherichia coli. However, two distinct V. vulnificus genotypes or alleles were associated with the operon, and they diverged at sequences encoding hypothetical proteins and also at unique, intergenic repetitive DNA elements. Phase variation was examined under conditions that promoted high-frequency transition of Op to Tr forms. Recovery of Tr isolates in these experiments showed multiple genotypes, which were designated TR1, TR2, and TR3: CPS operons of TR1 isolates were identical to the Op parent, and cells remained phase variable but expressed reduced CPS. TR2 and TR3 showed deletion mutations in one (wzb) or multiple genes, respectively, and deletion mutants were acapsular and locked in the Tr phase. Complementation in trans restored the Op phenotype in strains with the wzb deletion mutation. Allelic variation in repetitive elements determined the locations, rates, and extents of deletion mutations. Thus, different mechanisms are responsible for reversible phase variation in CPS expression versus genetic deletions in the CPS operon of V. vulnificus. Repetitive-element-mediated deletion mutations were highly conserved within the species and are likely to promote survival in estuarine environments.
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Affiliation(s)
- Maria Chatzidaki-Livanis
- University of Florida, Department of Food Science and Human Nutrition, P.O. Box 110370, Gainesville, FL 32611, USA
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Park NY, Lee JH, Kim MW, Jeong HG, Lee BC, Kim TS, Choi SH. Identification of the Vibrio vulnificus wbpP gene and evaluation of its role in virulence. Infect Immun 2006; 74:721-8. [PMID: 16369029 PMCID: PMC1346593 DOI: 10.1128/iai.74.1.721-728.2006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A wbpP gene encoding a putative UDP-N-acetyl-D-glucosamine C(4) epimerase was identified and cloned from Vibrio vulnificus. The functions of the wbpP gene, assessed by the construction of an isogenic mutant and by evaluating its phenotype changes, demonstrated that WbpP is essential in both the pathogenesis and the capsular polysaccharide biosynthesis of V. vulnificus.
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Affiliation(s)
- Na Young Park
- Department of Food Science and Technology, School of Agricultural Biotechnology, Center for Agricultural Biomaterials, Seoul National University, Seoul 151-742, South Korea
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Kim YR, Kim SY, Kim CM, Lee SE, Rhee JH. Essential role of an adenylate cyclase in regulating Vibrio vulnificus virulence. FEMS Microbiol Lett 2005; 243:497-503. [PMID: 15686854 DOI: 10.1016/j.femsle.2005.01.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Revised: 12/01/2004] [Accepted: 01/10/2005] [Indexed: 11/24/2022] Open
Abstract
Vibrio vulnificus, a halophilic estuarine bacterium, causes a fatal septicemia and necrotizing wound infection. To investigate the role of cAMP in V. vulnificus virulence regulation, an in-frame deletion mutant of the cya gene encoding adenylate cyclase was constructed. The cya null mutation resulted in a pleiotropic change of virulence phenotypes. The production of hemolysin and protease, the motility, and the cytotoxicity were decreased by the cya mutation. The defects in the cya mutant were functionally complemented in trans by a plasmid carrying the wild type cya allele. The V. vulnificus cya mutant exhibited a 100-fold increase in LD50 to mice. The result indicates that cAMP plays an essential role in the global regulation of V. vulnificus virulence.
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Affiliation(s)
- Young Ran Kim
- Research Institute of Vibrio Infection and Genome Research Center for Enteropathogenic Bacteria, Chonnam National University Medical School, Gwangju 501-746, South Korea
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38
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Grau BL, Henk MC, Pettis GS. High-frequency phase variation of Vibrio vulnificus 1003: isolation and characterization of a rugose phenotypic variant. J Bacteriol 2005; 187:2519-25. [PMID: 15774896 PMCID: PMC1065241 DOI: 10.1128/jb.187.7.2519-2525.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The marine bacterium Vibrio vulnificus is a human pathogen that can spontaneously switch between virulent opaque and avirulent translucent phenotypes. Here, we document an additional form, the rugose variant, which produces copious biofilms and which may contribute both to pathogenicity of V. vulnificus and to its survival under adverse environmental conditions.
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Affiliation(s)
- Brenda L Grau
- Department of Biological Sciences, 107 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803, USA.
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39
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Abstract
Vibrios are ubiquitous and abundant in the aquatic environment. A high abundance of vibrios is also detected in tissues and/or organs of various marine algae and animals, e.g., abalones, bivalves, corals, fish, shrimp, sponges, squid, and zooplankton. Vibrios harbour a wealth of diverse genomes as revealed by different genomic techniques including amplified fragment length polymorphism, multilocus sequence typing, repetetive extragenic palindrome PCR, ribotyping, and whole-genome sequencing. The 74 species of this group are distributed among four different families, i.e., Enterovibrionaceae, Photobacteriaceae, Salinivibrionaceae, and Vibrionaceae. Two new genera, i.e., Enterovibrio norvegicus and Grimontia hollisae, and 20 novel species, i.e., Enterovibrio coralii, Photobacterium eurosenbergii, V. brasiliensis, V. chagasii, V. coralliillyticus, V. crassostreae, V. fortis, V. gallicus, V. hepatarius, V. hispanicus, V. kanaloaei, V. neonatus, V. neptunius, V. pomeroyi, V. pacinii, V. rotiferianus, V. superstes, V. tasmaniensis, V. ezurae, and V. xuii, have been described in the last few years. Comparative genome analyses have already revealed a variety of genomic events, including mutations, chromosomal rearrangements, loss of genes by decay or deletion, and gene acquisitions through duplication or horizontal transfer (e.g., in the acquisition of bacteriophages, pathogenicity islands, and super-integrons), that are probably important driving forces in the evolution and speciation of vibrios. Whole-genome sequencing and comparative genomics through the application of, e.g., microarrays will facilitate the investigation of the gene repertoire at the species level. Based on such new genomic information, the taxonomy and the species concept for vibrios will be reviewed in the next years.
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Affiliation(s)
- Fabiano L Thompson
- Laboratory of Microbiology, Ghent University, K.L. Ledeganckstraat 35, Ghent 9000, Belgium.
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Chen CY, Wu KM, Chang YC, Chang CH, Tsai HC, Liao TL, Liu YM, Chen HJ, Shen ABT, Li JC, Su TL, Shao CP, Lee CT, Hor LI, Tsai SF. Comparative genome analysis of Vibrio vulnificus, a marine pathogen. Genome Res 2004; 13:2577-87. [PMID: 14656965 PMCID: PMC403799 DOI: 10.1101/gr.1295503] [Citation(s) in RCA: 310] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The halophile Vibrio vulnificus is an etiologic agent of human mortality from seafood-borne infections. We applied whole-genome sequencing and comparative analysis to investigate the evolution of this pathogen. The genome of biotype 1 strain, V. vulnificus YJ016, was sequenced and includes two chromosomes of estimated 3377 kbp and 1857 kbp in size, and a plasmid of 48,508 bp. A super-integron (SI) was identified, and the SI region spans 139 kbp and contains 188 gene cassettes. In contrast to non-SI sequences, the captured gene cassettes are unique for any given Vibrio species and are highly variable among V. vulnificus strains. Multiple rearrangements were found when comparing the 5.3-Mbp V. vulnificus YJ016 genome and the 4.0-Mbp V. cholerae El Tor N16961 genome. The organization of gene clusters of capsular polysaccharide, iron metabolism, and RTX toxin showed distinct genetic features of V. vulnificus and V. cholerae. The content of the V. vulnificus genome contained gene duplications and evidence of horizontal transfer, allowing for genetic diversity and function in the marine environment. The genomic information obtained in this study can be applied to monitoring vibrio infections and identifying virulence genes in V. vulnificus.
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Affiliation(s)
- Chung-Yung Chen
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Taipei 115, Taiwan
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Güvener ZT, McCarter LL. Multiple regulators control capsular polysaccharide production in Vibrio parahaemolyticus. J Bacteriol 2003; 185:5431-41. [PMID: 12949095 PMCID: PMC193756 DOI: 10.1128/jb.185.18.5431-5441.2003] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio parahaemolyticus, a biofouling marine bacterium and human pathogen, undergoes phase variation displaying translucent (TR) and opaque (OP) colony morphologies. Prior studies demonstrated that OP colonies produce more capsular polysaccharide (CPS) than TR colonies and that opacity is controlled by the Vibrio harveyi LuxR-type transcriptional activator OpaR. CPS has also been shown to be regulated by the scrABC signaling pathway, which involves a GGDEF-EAL motif-containing sensory protein. The present study identifies cps genes and examines their regulation. Transposon insertions in the cps locus, which contains 11 genes, abolished opacity. Such mutants failed to produce CPS and were defective in pellicle formation in microtiter wells and in a biofilm attachment assay. Reporter fusions to cpsA, the first gene in the locus, showed approximately 10-fold-enhanced transcription in the OP (opaR+) strain compared to a TR (deltaopaR) strain. Two additional transcriptional regulators were discovered. One potential activator, CpsR, participates in the scrABC GGDEF-EAL-signaling pathway; CpsR was required for the increased cps expression observed in scrA deltaopaR strains. CpsR, which contains a conserved module found in members of the AAA+ superfamily of ATP-interacting proteins, is homologous to Vibrio cholerae VpsR; however, unlike VpsR, CpsR was not essential for cps expression. CpsS, the second newly identified regulator, contains a CsgD-type DNA-binding domain and appears to act as a repressor. Mutants with cpsS defects have greatly elevated cps transcription; their high level of cpsA expression was CpsR dependent in TR strains and primarily OpaR dependent in OP strains. Thus, a network of positive and negative regulators modulates CPS production in V. parahaemolyticus.
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Affiliation(s)
- Zehra Tüzün Güvener
- Department of Microbiology, The University of Iowa, Iowa City, Iowa 52242, USA
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