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Lyou ES, Kim MS, Kim SB, Park M, Kim KD, Jung WH, Lee TK. Single-cell phenotypes revealed as a key biomarker in bacterial-fungal interactions: a case study of Staphylococcus and Malassezia. Microbiol Spectr 2023; 11:e0043723. [PMID: 37909790 PMCID: PMC10714763 DOI: 10.1128/spectrum.00437-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023] Open
Abstract
IMPORTANCE Evaluating bacterial-fungal interactions is important for understanding ecological functions in a natural habitat. Many studies have defined bacterial-fungal interactions according to changes in growth rates when co-cultivated. However, the current literature lacks detailed studies on phenotypic changes in single cells associated with transcriptomic profiles to understand the bacterial-fungal interactions. In our study, we measured the single-cell phenotypes of bacteria co-cultivated with fungi using Raman spectroscopy with its transcriptomic profiles and determined the consequence of these interactions in detail. This rapid and reliable phenotyping approach has the potential to provide new insights regarding bacterial-fungal interactions.
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Affiliation(s)
- Eun Sun Lyou
- Department of Environmental & Energy Engineering, Yonsei University, Wonju, South Korea
| | - Min Sung Kim
- Department of Environmental & Energy Engineering, Yonsei University, Wonju, South Korea
- Bio-Chemical Analysis Group, Centre for Research Equipment, Korea Basic Science Institute, Cheongju, South Korea
| | - Soo Bin Kim
- Department of Environmental & Energy Engineering, Yonsei University, Wonju, South Korea
| | - MinJi Park
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Kyong-Dong Kim
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Tae Kwon Lee
- Department of Environmental & Energy Engineering, Yonsei University, Wonju, South Korea
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2
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Koeksoy E, Bezuidt OM, Bayer T, Chan CS, Emerson D. Zetaproteobacteria Pan-Genome Reveals Candidate Gene Cluster for Twisted Stalk Biosynthesis and Export. Front Microbiol 2021; 12:679409. [PMID: 34220764 PMCID: PMC8250860 DOI: 10.3389/fmicb.2021.679409] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/06/2021] [Indexed: 12/15/2022] Open
Abstract
Twisted stalks are morphologically unique bacterial extracellular organo-metallic structures containing Fe(III) oxyhydroxides that are produced by microaerophilic Fe(II)-oxidizers belonging to the Betaproteobacteria and Zetaproteobacteria. Understanding the underlying genetic and physiological mechanisms of stalk formation is of great interest based on their potential as novel biogenic nanomaterials and their relevance as putative biomarkers for microbial Fe(II) oxidation on ancient Earth. Despite the recognition of these special biominerals for over 150 years, the genetic foundation for the stalk phenotype has remained unresolved. Here we present a candidate gene cluster for the biosynthesis and secretion of the stalk organic matrix that we identified with a trait-based analyses of a pan-genome comprising 16 Zetaproteobacteria isolate genomes. The “stalk formation in Zetaproteobacteria” (sfz) cluster comprises six genes (sfz1-sfz6), of which sfz1 and sfz2 were predicted with functions in exopolysaccharide synthesis, regulation, and export, sfz4 and sfz6 with functions in cell wall synthesis manipulation and carbohydrate hydrolysis, and sfz3 and sfz5 with unknown functions. The stalk-forming Betaproteobacteria Ferriphaselus R-1 and OYT-1, as well as dread-forming Zetaproteobacteria Mariprofundus aestuarium CP-5 and Mariprofundus ferrinatatus CP-8 contain distant sfz gene homologs, whereas stalk-less Zetaproteobacteria and Betaproteobacteria lack the entire gene cluster. Our pan-genome analysis further revealed a significant enrichment of clusters of orthologous groups (COGs) across all Zetaproteobacteria isolate genomes that are associated with the regulation of a switch between sessile and motile growth controlled by the intracellular signaling molecule c-di-GMP. Potential interactions between stalk-former unique transcription factor genes, sfz genes, and c-di-GMP point toward a c-di-GMP regulated surface attachment function of stalks during sessile growth.
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Affiliation(s)
- Elif Koeksoy
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States.,Leibniz Institute DSMZ (German Collection of Microorganisms and Cell Cultures), Braunschweig, Germany
| | - Oliver M Bezuidt
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
| | - Timm Bayer
- Geomicrobiology Group, Center for Applied Geoscience, University of Tübingen, Tübingen, Germany
| | - Clara S Chan
- Department of Earth Sciences, University of Delaware, Newark, DE, United States.,School of Marine Sciences and Policy, University of Delaware, Newark, DE, United States
| | - David Emerson
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
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Pili and other surface proteins influence the structure and the nanomechanical properties of Lactococcus lactis biofilms. Sci Rep 2021; 11:4846. [PMID: 33649417 PMCID: PMC7921122 DOI: 10.1038/s41598-021-84030-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/09/2021] [Indexed: 11/08/2022] Open
Abstract
Lactic acid bacteria, in particular Lactococcus lactis, are widely used in the food industry, for the control and/or the protection of the manufacturing processes of fermented food. While L. lactis has been reported to form compact and uniform biofilms it was recently shown that certain strains able to display pili at their surface form more complex biofilms exhibiting heterogeneous and aerial structures. As the impact of those biofilm structures on the biomechanical properties of the biofilms is poorly understood, these were investigated using AFM force spectroscopy and imaging. Three types of strains were used i.e., a control strain devoid of pili and surface mucus-binding protein, a strain displaying pili but no mucus-binding proteins and a strain displaying both pili and a mucus-binding protein. To identify potential correlations between the nanomechanical measurements and the biofilm architecture, 24-h old biofilms were characterized by confocal laser scanning microscopy. Globally the strains devoid of pili displayed smoother and stiffer biofilms (Young Modulus of 4-100 kPa) than those of piliated strains (Young Modulus around 0.04-0.1 kPa). Additional display of a mucus-binding protein did not affect the biofilm stiffness but made the biofilm smoother and more compact. Finally, we demonstrated the role of pili in the biofilm cohesiveness by monitoring the homotypic adhesion of bacteria to the biofilm surface. These results will help to understand the role of pili and mucus-binding proteins withstanding external forces.
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Todhanakasem T, Triwattana K, Pom J, Havanapan P, Koombhongse P, Thitisak P. Physiological studies of the Pediococcus pentosaceus biofilm. Lett Appl Microbiol 2021; 72:178-186. [PMID: 33059384 DOI: 10.1111/lam.13351] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/25/2020] [Accepted: 07/05/2020] [Indexed: 12/19/2022]
Abstract
Pediococcus pentosaceus, a bacterium recently used in human and animal probiotics, was used in combination with supports made from polylactic acid composite soybean meal was used to study biofilm formation, and it was found that dense biofilms developed by Day 1. Proteomic comparison between planktonic and biofilm cultures of P. pentosaceus showed distinct expression patterns of intracellular and extracellular proteins. Type I glyceraldehyde-3-phosphate dehydrogenase was upregulated in biofilm cultures and mediated cell adhesion and encouraged biofilm production. GMP synthase, which regulates GMP synthesis and acts as an intracellular signal molecule to control cell mechanisms and has been exploited in the development of new therapeutic agents, was also upregulated in the biofilm mode of growth. The present work serves as a basis for future studies examining the complex network of systems that regulate lactic acid bacterial (LAB) biofilm formation and can serve as a framework for studies of production of therapeutic agents from LAB.
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Affiliation(s)
- T Todhanakasem
- Department of Agro-Industry, Faculty of Biotechnology, Assumption University, Bangkapi, Bangkok, Thailand
| | - K Triwattana
- Department of Agro-Industry, Faculty of Biotechnology, Assumption University, Bangkapi, Bangkok, Thailand
| | - J Pom
- Department of Agro-Industry, Faculty of Biotechnology, Assumption University, Bangkapi, Bangkok, Thailand
| | - P Havanapan
- Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand
| | - P Koombhongse
- National Metal and Materials Technology Center (MTEC), Klong Luang, Thailand
| | - P Thitisak
- K.M.P. Biotech Co. Ltd, Chon Buri, Thailand
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5
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Proteomic analysis reveals the temperature-dependent presence of extracytoplasmic peptidases in the biofilm exoproteome of Listeria monocytogenes EGD-e. J Microbiol 2020; 58:761-771. [PMID: 32719941 DOI: 10.1007/s12275-020-9522-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 06/03/2020] [Accepted: 06/15/2020] [Indexed: 02/03/2023]
Abstract
The foodborne pathogen Listeria monocytogenes resists environmental stresses by forming biofilms. Because this pathogen transmits between the environment and the host, it must adapt to temperature as an environmental stress. In this study, we aimed to identify which proteins were present depending on the temperature in the biofilms of L. monocytogenes EGD-e. Proteins in the supernatants of biofilms formed at 25°C and 37°C were compared using two-dimensional gel electrophoresis and liquid chromatography with tandem mass spectrometry. The larger number of extracytoplasmic proteins associated with cell wall/membrane/envelop biogenesis was identified from the supernatant of biofilms formed at 25°C (7) than those at 37°C (0). Among the 16 extracytoplasmic proteins detected only at 25°C, three were peptidases, namely Spl, Cwh, and Lmo0186. Moreover, mRNA expression of the three peptidases was higher at 25°C than at 37°C. Interestingly, this adaptation of gene expression to temperature was present in sessile cells but not in dispersed cells. After inhibiting the activity of extracytoplasmic peptidases with a protease inhibitor, we noted that the levels of biofilm biomass increased with higher concentrations of the protease inhibitor only when L. monocytogenes grew biofilms at 25°C and not at 37°C. Overall, our data suggest an effect of temperature on the presence of peptidases in L. monocytogenes biofilms. Additionally, increasing the levels of extracytoplasmic peptidases in biofilms is likely a unique feature for sessile L. monocytogenes that causes a naturally occurring breakdown of biofilms and facilitates the pathogen exiting biofilms and disseminating into the environment.
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Inactivation of the sfgtr4 Gene of Shigella flexneri Induces Biofilm Formation and Affects Bacterial Pathogenicity. Microorganisms 2020; 8:microorganisms8060841. [PMID: 32512756 PMCID: PMC7355660 DOI: 10.3390/microorganisms8060841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/08/2020] [Accepted: 05/21/2020] [Indexed: 01/08/2023] Open
Abstract
Biofilm formation is a significant cause for the environmental persistence of foodborne pathogens. This phenomenon remains misunderstood in Shigellaflexneri whose pathogenicity is mainly associated with the virulence plasmid pWR100. Sequence analysis of the latter predicts a putative lipopolysaccharides (LPS) glycosyltransferase (Gtr) encoded by Sfgtr4, which is the second gene of the SfpgdA-orf186-virK-msbB2 locus. We demonstrated here that purified SfGtr4 exhibited a Gtr activity in vitro by transferring glucose to lipid A. To establish the role of SfGtr4 in virulence, we generated a Sfgtr4 mutant and assessed its phenotype in vitro. Sfgtr4 mutant significantly reduced HeLa cells invasion without impairing type III effectors secretion, increased susceptibility to lysozyme degradation, and enhanced bacterial killing by polymorphonuclear neutrophils (PMNs). SfGtr4 is related to proteins required in biofilm formation. We established conditions whereby wild-type Shigella formed biofilm and revealed that its appearance was accelerated by the Sfgtr4 mutant. Additional phenotypical analysis revealed that single SfpdgA and double SfpgdA-Sfgtr4 mutants behaved similarly to Sfgtr4 mutant. Furthermore, a molecular interaction between SfGtr4 and SfPgdA was identified. In summary, the dual contribution of SfGtr4 and SfPgdA to the pathogenicity and the regulation biofilm formation by S. flexneri was demonstrated here.
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Garrett EM, Sekulovic O, Wetzel D, Jones JB, Edwards AN, Vargas-Cuebas G, McBride SM, Tamayo R. Phase variation of a signal transduction system controls Clostridioides difficile colony morphology, motility, and virulence. PLoS Biol 2019; 17:e3000379. [PMID: 31658249 PMCID: PMC6837544 DOI: 10.1371/journal.pbio.3000379] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 11/07/2019] [Accepted: 10/15/2019] [Indexed: 12/20/2022] Open
Abstract
Recent work has revealed that Clostridioides difficile, a major cause of nosocomial diarrheal disease, exhibits phenotypic heterogeneity within a clonal population as a result of phase variation. Many C. difficile strains representing multiple ribotypes develop two colony morphotypes, termed rough and smooth, but the biological implications of this phenomenon have not been explored. Here, we examine the molecular basis and physiological relevance of the distinct colony morphotypes produced by this bacterium. We show that C. difficile reversibly differentiates into rough and smooth colony morphologies and that bacteria derived from the isolates display discrete motility behaviors. We identified an atypical phase-variable signal transduction system consisting of a histidine kinase and two response regulators, named herein colony morphology regulators RST (CmrRST), which mediates the switch in colony morphology and motility behaviors. The CmrRST-regulated surface motility is independent of flagella and type IV pili, suggesting a novel mechanism of cell migration in C. difficile. Microscopic analysis of cell and colony structure indicates that CmrRST promotes the formation of elongated bacteria arranged in bundled chains, which may contribute to bacterial migration on surfaces. In a hamster model of acute C. difficile disease, the CmrRST system is required for disease development. Furthermore, we provide evidence that CmrRST phase varies during infection, suggesting that the intestinal environment impacts the proportion of CmrRST-expressing C. difficile. Our findings indicate that C. difficile employs phase variation of the CmrRST signal transduction system to generate phenotypic heterogeneity during infection, with concomitant effects on bacterial physiology and pathogenesis.
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Affiliation(s)
- Elizabeth M. Garrett
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Ognjen Sekulovic
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Daniela Wetzel
- Department of Microbiology and Immunology, Emory University, Rollins Research Center, Atlanta, Georgia, United States of America
| | - Joshua B. Jones
- Department of Microbiology and Immunology, Emory University, Rollins Research Center, Atlanta, Georgia, United States of America
| | - Adrianne N. Edwards
- Department of Microbiology and Immunology, Emory University, Rollins Research Center, Atlanta, Georgia, United States of America
| | - Germán Vargas-Cuebas
- Department of Microbiology and Immunology, Emory University, Rollins Research Center, Atlanta, Georgia, United States of America
| | - Shonna M. McBride
- Department of Microbiology and Immunology, Emory University, Rollins Research Center, Atlanta, Georgia, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
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8
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Roles of lytic transglycosylases in biofilm formation and β-lactam resistance in methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2019:AAC.01277-19. [PMID: 31570396 DOI: 10.1128/aac.01277-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is responsible for numerous community outbreaks and is one of the most frequent causes of nosocomial infections with significant morbidity and mortality. While the function of lytic transglycosylases (LTs) in relation to cell division, biofilm formation, and antibiotic resistance has been determined for several bacteria, their role in S. aureus remains largely unknown. The only known LTs in S. aureus are immunodominant staphylococcal antigen A (IsaA) and Staphylococcus epidermidis D protein (SceD). Our study demonstrates that, in a strain of methicillin-resistant S. aureus (MRSA), IsaA and SceD contribute differently to biofilm formation and β-lactam resistance. Deletion of isaA, but not sceD, led to decreased biofilm formation. Additionally, in isaA-deleted strains, β-lactam resistance was significantly decreased compared to that of wild-type strains. Plasmid-based expression of mecA, a major determinant of β-lactam resistance in MRSA, in an isaA-deleted strain did not restore β-lactam resistance, demonstrating that the β-lactam susceptibility phenotype is exhibited by isaA mutant regardless of the production level of PBP2a. Overall, our results suggest that IsaA is a potential therapeutic target for MRSA infections.
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9
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Gaudu P, Yamamoto Y, Jensen PR, Hammer K, Lechardeur D, Gruss A. Genetics of Lactococci. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0035-2018. [PMID: 31298208 PMCID: PMC10957224 DOI: 10.1128/microbiolspec.gpp3-0035-2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Indexed: 11/20/2022] Open
Abstract
Lactococcus lactis is the best characterized species among the lactococci, and among the most consumed food-fermenting bacteria worldwide. Thanks to their importance in industrialized food production, lactococci are among the lead bacteria understood for fundamental metabolic pathways that dictate growth and survival properties. Interestingly, lactococci belong to the Streptococcaceae family, which includes food, commensal and virulent species. As basic metabolic pathways (e.g., respiration, metal homeostasis, nucleotide metabolism) are now understood to underlie virulence, processes elucidated in lactococci could be important for understanding pathogen fitness and synergy between bacteria. This chapter highlights major findings in lactococci and related bacteria, and covers five themes: distinguishing features of lactococci, metabolic capacities including the less known respiration metabolism in Streptococcaceae, factors and pathways modulating stress response and fitness, interbacterial dialogue via metabolites, and novel applications in health and biotechnology.
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Affiliation(s)
| | - Yuji Yamamoto
- Laboratory of Cellular Microbiology, School of Veterinary Medicine, Kitasato University, Towada, 034-8628, Aomori Japan
| | - Peter Ruhdal Jensen
- National Food Institute, Technical University of Denmark, DK-2800 Lyngby, Denmark
| | - Karin Hammer
- DTU Bioengineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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Abstract
Pathogenic oral biofilms are universal, chronic, and costly. Despite advances in understanding the mechanisms of biofilm formation and persistence, novel and effective treatment options remain scarce. Nanoparticle-mediated eradication of the biofilm matrix and resident bacteria holds great potential. In particular, nanoparticles that target specific microbial and biofilm features utilizing nontoxic materials are well-suited for clinical translation. However, much work remains to characterize the local and systemic effects of therapeutic agents that are topically applied to chronic biofilms, such as those that cause dental caries. In this Perspective, we summarize the pathogenesis of oral biofilms, describe current and future nanoparticle-mediated treatment approaches, and highlight outstanding questions that are paramount to answer for effectively targeting and treating oral biofilms.
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Vermassen A, Leroy S, Talon R, Provot C, Popowska M, Desvaux M. Cell Wall Hydrolases in Bacteria: Insight on the Diversity of Cell Wall Amidases, Glycosidases and Peptidases Toward Peptidoglycan. Front Microbiol 2019; 10:331. [PMID: 30873139 PMCID: PMC6403190 DOI: 10.3389/fmicb.2019.00331] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/08/2019] [Indexed: 11/13/2022] Open
Abstract
The cell wall (CW) of bacteria is an intricate arrangement of macromolecules, at least constituted of peptidoglycan (PG) but also of (lipo)teichoic acids, various polysaccharides, polyglutamate and/or proteins. During bacterial growth and division, there is a constant balance between CW degradation and biosynthesis. The CW is remodeled by bacterial hydrolases, whose activities are carefully regulated to maintain cell integrity or lead to bacterial death. Each cell wall hydrolase (CWH) has a specific role regarding the PG: (i) cell wall amidase (CWA) cleaves the amide bond between N-acetylmuramic acid and L-alanine residue at the N-terminal of the stem peptide, (ii) cell wall glycosidase (CWG) catalyses the hydrolysis of the glycosidic linkages, whereas (iii) cell wall peptidase (CWP) cleaves amide bonds between amino acids within the PG chain. After an exhaustive overview of all known conserved catalytic domains responsible for CWA, CWG, and CWP activities, this review stresses that the CWHs frequently display a modular architecture combining multiple and/or different catalytic domains, including some lytic transglycosylases as well as CW binding domains. From there, direct physiological and collateral roles of CWHs in bacterial cells are further discussed.
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Affiliation(s)
- Aurore Vermassen
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Sabine Leroy
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Régine Talon
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | | | - Magdalena Popowska
- Department of Applied Microbiology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
| | - Mickaël Desvaux
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
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Arioli S, Eraclio G, Della Scala G, Neri E, Colombo S, Scaloni A, Fortina MG, Mora D. Role of Temperate Bacteriophage ϕ20617 on Streptococcus thermophilus DSM 20617 T Autolysis and Biology. Front Microbiol 2018; 9:2719. [PMID: 30473689 PMCID: PMC6237837 DOI: 10.3389/fmicb.2018.02719] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 10/24/2018] [Indexed: 12/19/2022] Open
Abstract
Streptococcus thermophilus DSM 20167T showed autolytic behavior when cultured in lactose- and sucrose-limited conditions. The amount of cell lysis induced was inversely related to the energetic status of the cells, as demonstrated by exposing cells to membrane-uncoupling and glycolysis inhibitors. Genome sequence analysis of strain DSM 20617T revealed the presence of a pac-type temperate bacteriophage, designated Φ20617, whose genomic organization and structure resemble those of temperate streptococcal bacteriophages. The prophage integrated at the 3'-end of the gene encoding the glycolytic enzyme enolase (eno), between eno and the lipoteichoic acid synthase-encoding gene ltaS, affecting their transcription. Comparative experiments conducted on the wild-type strain and a phage-cured derivative strain revealed that the cell-wall integrity of the lysogenic strain was compromised even in the absence of detectable cell lysis. More importantly, adhesion to solid surfaces and heat resistance were significantly higher in the lysogenic strain than in the phage-cured derivative. The characterization of the phenotype of a lysogenic S. thermophilus and its phage-cured derivative is relevant to understanding the ecological constraints that drive the stable association between a temperate phage and its bacterial host.
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Affiliation(s)
- Stefania Arioli
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy
| | - Giovanni Eraclio
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy.,Sacco Srl, Cadorago, Italy
| | - Giulia Della Scala
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy.,Sacco Srl, Cadorago, Italy
| | - Eros Neri
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy.,Sacco Srl, Cadorago, Italy
| | - Stefano Colombo
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy
| | - Andrea Scaloni
- Proteomics and Mass Spectrometry Laboratory, Istituto per il Sistema Produzione Animale in Ambiente Mediterraneo, National Research Council, Naples, Italy
| | - Maria Grazia Fortina
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy
| | - Diego Mora
- Department of Food Environmental and Nutritional Sciences, University of Milan, Milan, Italy
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13
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Resuscitation-Promoting Factors Are Required for Mycobacterium smegmatis Biofilm Formation. Appl Environ Microbiol 2018; 84:AEM.00687-18. [PMID: 29915116 DOI: 10.1128/aem.00687-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/10/2018] [Indexed: 12/19/2022] Open
Abstract
Resuscitation-promoting factors (Rpfs) have previously been shown to act as growth-stimulatory molecules via their lysozyme-like activity on peptidoglycan in the bacterial cell wall. In this study, we investigated the ability of Mycobacterium smegmatis strains lacking rpf genes to form biofilms and tested their susceptibilities to cell wall-targeting agents. M. smegmatis contains four distinct rpf homologues, namely, MSMEG_5700 (rpfA), MSMEG_5439 (rpfB), MSMEG_4640 (rpfE2), and MSMEG_4643 (rpfE). During axenic growth of the wild-type strain, all four mRNA transcripts were expressed to various degrees, but the expression of MSMEG_4643 was significantly greater during exponential growth. Similarly, all rpf mRNA transcripts could be detected in biofilms grown for 7, 14, and 28 days, with MSMEG_4643 expressed at the highest abundance after 7 days. In-frame unmarked deletion mutants (single and combinatorial) were generated and displayed altered colony morphologies and the inability to form typical biofilms. Moreover, any strain lacking rpfA and rpfB simultaneously exhibited increased susceptibility to rifampin, vancomycin, and SDS. Exogenous Rpf supplementation in the form of culture filtrate failed to restore biofilm formation. Liquid chromatography-mass spectrometry (LC-MS) analysis of peptidoglycan (PG) suggested a reduction in 4-3 cross-linked PG in the ΔrpfABEE2 mutant strain. In addition, the level of PG-repeat units terminating in 1,6-anhydroMurNAc appeared to be significantly reduced in the quadruple rpf mutant. Collectively, our data have shown that Rpfs play an important role in biofilm formation, possibly through alterations in PG cross-linking and the production of signaling molecules.IMPORTANCE The cell wall of pathogenic mycobacteria is composed of peptidoglycan, arabinogalactan, mycolic acids, and an outer capsule. This inherent complexity renders it resistant to many antibiotics. Consequently, its biosynthesis and remodeling during growth directly impact viability. Resuscitation-promoting factors (Rpfs), enzymes with lytic transglycosylase activity, have been associated with the revival of dormant cells and subsequent resumption of vegetative growth. Mycobacterium smegmatis, a soil saprophyte and close relative of the human pathogen Mycobacterium tuberculosis, encodes four distinct Rpfs. Herein, we assessed the relationship between Rpfs and biofilm formation, which is used as a model to study drug tolerance and bacterial signaling in mycobacteria. We demonstrated that progressive deletion of rpf genes hampered the development of biofilms and reduced drug tolerance. These effects were accompanied by a reduction in muropeptide production and altered peptidoglycan cross-linking. Collectively, these observations point to an important role for Rpfs in mycobacterial communication and drug tolerance.
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14
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David B, Duchêne MC, Haustenne GL, Pérez-Núñez D, Chapot-Chartier MP, De Bolle X, Guédon E, Hols P, Hallet B. PBP2b plays a key role in both peripheral growth and septum positioning in Lactococcus lactis. PLoS One 2018; 13:e0198014. [PMID: 29791496 PMCID: PMC5965867 DOI: 10.1371/journal.pone.0198014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/11/2018] [Indexed: 12/11/2022] Open
Abstract
Lactococcus lactis is an ovoid bacterium that forms filaments during planktonic and biofilm lifestyles by uncoupling cell division from cell elongation. In this work, we investigate the role of the leading peptidoglycan synthase PBP2b that is dedicated to cell elongation in ovococci. We show that the localization of a fluorescent derivative of PBP2b remains associated to the septal region and superimposed with structural changes of FtsZ during both vegetative growth and filamentation indicating that PBP2b remains intimately associated to the division machinery during the whole cell cycle. In addition, we show that PBP2b-negative cells of L. lactis are not only defective in peripheral growth; they are also affected in septum positioning. This septation defect does not simply result from the absence of the protein in the cell growth machinery since it is also observed when PBP2b-deficient cells are complemented by a catalytically inactive variant of PBP2b. Finally, we show that round cells resulting from β-lactam treatment are not altered in septation, suggesting that shape elongation as such is not a major determinant for selection of the division site. Altogether, we propose that the specific PBP2b transpeptidase activity at the septum plays an important role for tagging future division sites during L. lactis cell cycle.
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Affiliation(s)
- Blandine David
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Marie-Clémence Duchêne
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Gabrielle Laurie Haustenne
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Daniel Pérez-Núñez
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | | | - Xavier De Bolle
- Microorganisms Biology Research Unit (URBM), University of Namur (UNamur), Namur, Belgium
| | - Eric Guédon
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
- STLO, INRA, Agrocampus Ouest, Rennes, France
| | - Pascal Hols
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- * E-mail: (BH); (PH)
| | - Bernard Hallet
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- * E-mail: (BH); (PH)
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15
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Role of cell surface composition and lysis in static biofilm formation by Lactobacillus plantarum WCFS1. Int J Food Microbiol 2018; 271:15-23. [PMID: 29477805 DOI: 10.1016/j.ijfoodmicro.2018.02.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 01/26/2018] [Accepted: 02/11/2018] [Indexed: 01/20/2023]
Abstract
Next to applications in fermentations, Lactobacillus plantarum is recognized as a food spoilage organism, and its dispersal from biofilms in food processing environments might be implicated in contamination or recontamination of food products. This study provides new insights into biofilm development by L. plantarum WCFS1 through comparative analysis of wild type and mutants affected in cell surface composition, including mutants deficient in the production of Sortase A involved in the covalent attachment of 27 predicted surface proteins to the cell wall peptidoglycan (ΔsrtA) and mutants deficient in the production of capsular polysaccharides (CPS1-4, Δcps1-4). Surface adhesion and biofilm formation studies revealed none of the imposed cell surface modifications to affect the initial attachment of cells to polystyrene while biofilm formation based on Crystal Violet (CV) staining was severely reduced in the ΔsrtA mutant and significantly increased in mutants lacking the cps1 cluster, compared to the wild-type strain. Fluorescence microscopy analysis of biofilm samples pointed to a higher presence of extracellular DNA (eDNA) in cps1 mutants and this corresponded with increased autolysis activity. Subsequent studies using Δacm2 and ΔlytA derivatives affected in lytic behaviour revealed reduced biofilm formation measured by CV staining, confirming the relevance of lysis for the build-up of the biofilm matrix with eDNA.
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16
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Couvigny B, Kulakauskas S, Pons N, Quinquis B, Abraham AL, Meylheuc T, Delorme C, Renault P, Briandet R, Lapaque N, Guédon E. Identification of New Factors Modulating Adhesion Abilities of the Pioneer Commensal Bacterium Streptococcus salivarius. Front Microbiol 2018. [PMID: 29515553 PMCID: PMC5826255 DOI: 10.3389/fmicb.2018.00273] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Biofilm formation is crucial for bacterial community development and host colonization by Streptococcus salivarius, a pioneer colonizer and commensal bacterium of the human gastrointestinal tract. This ability to form biofilms depends on bacterial adhesion to host surfaces, and on the intercellular aggregation contributing to biofilm cohesiveness. Many S. salivarius isolates auto-aggregate, an adhesion process mediated by cell surface proteins. To gain an insight into the genetic factors of S. salivarius that dictate host adhesion and biofilm formation, we developed a screening method, based on the differential sedimentation of bacteria in semi-liquid conditions according to their auto-aggregation capacity, which allowed us to identify twelve mutations affecting this auto-aggregation phenotype. Mutations targeted genes encoding (i) extracellular components, including the CshA surface-exposed protein, the extracellular BglB glucan-binding protein, the GtfE, GtfG and GtfH glycosyltransferases and enzymes responsible for synthesis of cell wall polysaccharides (CwpB, CwpK), (ii) proteins responsible for the extracellular localization of proteins, such as structural components of the accessory SecA2Y2 system (Asp1, Asp2, SecA2) and the SrtA sortase, and (iii) the LiaR transcriptional response regulator. These mutations also influenced biofilm architecture, revealing that similar cell-to-cell interactions govern assembly of auto-aggregates and biofilm formation. We found that BglB, CshA, GtfH and LiaR were specifically associated with bacterial auto-aggregation, whereas Asp1, Asp2, CwpB, CwpK, GtfE, GtfG, SecA2 and SrtA also contributed to adhesion to host cells and host-derived components, or to interactions with the human pathogen Fusobacterium nucleatum. Our study demonstrates that our screening method could also be used to identify genes implicated in the bacterial interactions of pathogens or probiotics, for which aggregation is either a virulence trait or an advantageous feature, respectively.
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Affiliation(s)
- Benoit Couvigny
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Saulius Kulakauskas
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Nicolas Pons
- MetaGenoPoliS, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | - Benoit Quinquis
- MetaGenoPoliS, INRA, Université Paris-Saclay, Jouy-en-Josas, France
| | | | - Thierry Meylheuc
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France.,INRA, Plateforme MIMA2, Jouy-en-Josas, France
| | - Christine Delorme
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Pierre Renault
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Romain Briandet
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Nicolas Lapaque
- MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Eric Guédon
- STLO, UMR 1253, INRA, Agrocampus Ouest, Rennes, France
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17
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Piercey MJ, Ells TC, Macintosh AJ, Truelstrup Hansen L. Variations in biofilm formation, desiccation resistance and Benzalkonium chloride susceptibility among Listeria monocytogenes strains isolated in Canada. Int J Food Microbiol 2017; 257:254-261. [PMID: 28710947 DOI: 10.1016/j.ijfoodmicro.2017.06.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 04/18/2017] [Accepted: 06/25/2017] [Indexed: 11/17/2022]
Abstract
Listeria monocytogenes is a pathogenic foodborne microorganism noted for its ability to survive in the environment and food processing facilities. Survival may be related to the phenotype of individual strains including the ability to form biofilms and resist desiccation and/or sanitizer exposure. The objectives of this research were to compare 14 L. monocytogenes strains isolated from blood (3), food (6) and water (5) with respect to their benzalkonium chloride (BAC) sensitivity, desiccation resistance, and ability to form biofilm. Correlations were tested between those responses, and the presence of the SSI-1 (Stress Survival Islet) and LGI1/CC8 (Listeria Genomic Island 1 in a clonal complex 8 background) genetic markers. Genetic sequences from four strains representing different phenotypes were also probed for predicted amino acid differences in biofilm, desiccation, and membrane related genes. The water isolates were among the most desiccation susceptible strains, while strains exhibiting desiccation resistance harboured SSI-1 or both the SSI-1 and LGI1/CC8 markers. BAC resistance was greatest in planktonic LGI1/CC8 cells (relative to non-LGI1/CC8 cells), and higher BAC concentrations were also needed to inhibit the formation of biofilm by LGI1/CC8 strains during incubation for 48h and 6days compared to other strains. Formation of biofilm on stainless steel was not significantly (p>0.05) different among the strains. Analysis of genetic sequence data from desiccation and BAC sensitive (CP4 5-1, CP5 2-3, both from water), intermediate (Lm568, food) and desiccation and BAC resistant (08 5578, blood, human outbreak) strains led to the finding of amino acid differences in predicted functional protein domains in several biofilm, desiccation and peptidoglycan related genes (e.g., lmo0263, lmo0433, lmo0434, lmo0771, lmo0973, lmo1080, lmo1224, lmo1370, lmo1744, and lmo2558). Notably, the LGI1/CC8 strain 08-5578 had a frameshift mutation in lmo1370, a gene previously associated with desiccation resistance. In conclusion, the more desiccation and BAC resistant LGI1/CC8 isolates may pose a challenge for sanitation efforts.
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Affiliation(s)
- Marta J Piercey
- Department of Process Engineering and Applied Science, Dalhousie University, 1360 Barrington Street, Halifax B3H 4R2, Canada.
| | - Timothy C Ells
- Agriculture and Agri-Food Canada, 32 Main Street, Kentville, Nova Scotia, Canada.
| | - Andrew J Macintosh
- Department of Process Engineering and Applied Science, Dalhousie University, 1360 Barrington Street, Halifax B3H 4R2, Canada.
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18
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Arena MP, Capozzi V, Spano G, Fiocco D. The potential of lactic acid bacteria to colonize biotic and abiotic surfaces and the investigation of their interactions and mechanisms. Appl Microbiol Biotechnol 2017; 101:2641-2657. [PMID: 28213732 DOI: 10.1007/s00253-017-8182-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/01/2017] [Accepted: 02/03/2017] [Indexed: 12/23/2022]
Abstract
Lactic acid bacteria (LAB) are a heterogeneous group of Gram-positive bacteria that comprise several species which have evolved in close association with humans (food and lifestyle). While their use to ferment food dates back to very ancient times, in the last decades, LAB have attracted much attention for their documented beneficial properties and for potential biomedical applications. Some LAB are commensal that colonize, stably or transiently, host mucosal surfaces, inlcuding the gut, where they may contribute to host health. In this review, we present and discuss the main factors enabling LAB adaptation to such lifestyle, including the gene reprogramming accompanying gut colonization, the specific bacterial components involved in adhesion and interaction with host, and how the gut niche has shaped the genome of intestine-adapted species. Moreover, the capacity of LAB to colonize abiotic surfaces by forming structured communities, i.e., biofilms, is briefly discussed, taking into account the main bacterial and environmental factors involved, particularly in relation to food-related environments. The vast spread of LAB surface-associated communities and the ability to control their occurrence hold great potentials for human health and food safety biotechnologies.
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Affiliation(s)
- Mattia Pia Arena
- Department of Agriculture, Food and Environment Sciences, University of Foggia, via Napoli 25, 71122, Foggia, Italy
| | - Vittorio Capozzi
- Department of Agriculture, Food and Environment Sciences, University of Foggia, via Napoli 25, 71122, Foggia, Italy
| | - Giuseppe Spano
- Department of Agriculture, Food and Environment Sciences, University of Foggia, via Napoli 25, 71122, Foggia, Italy.
| | - Daniela Fiocco
- Department of Clinical and Experimental Medicine, University of Foggia, Viale Pinto 1, 71122, Foggia, Italy
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19
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Ribeiro SC, O'Connor PM, Ross RP, Stanton C, Silva CC. An anti-listerial Lactococcus lactis strain isolated from Azorean Pico cheese produces lacticin 481. Int Dairy J 2016. [DOI: 10.1016/j.idairyj.2016.07.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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20
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AcmB Is an S-Layer-Associated β-N-Acetylglucosaminidase and Functional Autolysin in Lactobacillus acidophilus NCFM. Appl Environ Microbiol 2016; 82:5687-97. [PMID: 27422832 PMCID: PMC5007774 DOI: 10.1128/aem.02025-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 12/23/2022] Open
Abstract
Autolysins, also known as peptidoglycan hydrolases, are enzymes that hydrolyze specific bonds within bacterial cell wall peptidoglycan during cell division and daughter cell separation. Within the genome of Lactobacillus acidophilus NCFM, there are 11 genes encoding proteins with peptidoglycan hydrolase catalytic domains, 9 of which are predicted to be functional. Notably, 5 of the 9 putative autolysins in L. acidophilus NCFM are S-layer-associated proteins (SLAPs) noncovalently colocalized along with the surface (S)-layer at the cell surface. One of these SLAPs, AcmB, a β-N-acetylglucosaminidase encoded by the gene lba0176 (acmB), was selected for functional analysis. In silico analysis revealed that acmB orthologs are found exclusively in S-layer- forming species of Lactobacillus. Chromosomal deletion of acmB resulted in aberrant cell division, autolysis, and autoaggregation. Complementation of acmB in the ΔacmB mutant restored the wild-type phenotype, confirming the role of this SLAP in cell division. The absence of AcmB within the exoproteome had a pleiotropic effect on the extracellular proteins covalently and noncovalently bound to the peptidoglycan, which likely led to the observed decrease in the binding capacity of the ΔacmB strain for mucin and extracellular matrices fibronectin, laminin, and collagen in vitro. These data suggest a functional association between the S-layer and the multiple autolysins noncovalently colocalized at the cell surface of L. acidophilus NCFM and other S-layer-producing Lactobacillus species. IMPORTANCELactobacillus acidophilus is one of the most widely used probiotic microbes incorporated in many dairy foods and dietary supplements. This organism produces a surface (S)-layer, which is a self-assembling crystalline array found as the outermost layer of the cell wall. The S-layer, along with colocalized associated proteins, is an important mediator of probiotic activity through intestinal adhesion and modulation of the mucosal immune system. However, there is still a dearth of information regarding the basic cellular and evolutionary function of S-layers. Here, we demonstrate that multiple autolysins, responsible for breaking down the cell wall during cell division, are associated with the S-layer. Deletion of the gene encoding one of these S-layer-associated autolysins confirmed its autolytic role and resulted in reduced binding capacity to mucin and intestinal extracellular matrices. These data suggest a functional association between the S-layer and autolytic activity through the extracellular presentation of autolysins.
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21
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Solopova A, Formosa-Dague C, Courtin P, Furlan S, Veiga P, Péchoux C, Armalyte J, Sadauskas M, Kok J, Hols P, Dufrêne YF, Kuipers OP, Chapot-Chartier MP, Kulakauskas S. Regulation of Cell Wall Plasticity by Nucleotide Metabolism in Lactococcus lactis. J Biol Chem 2016; 291:11323-36. [PMID: 27022026 DOI: 10.1074/jbc.m116.714303] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Indexed: 12/21/2022] Open
Abstract
To ensure optimal cell growth and separation and to adapt to environmental parameters, bacteria have to maintain a balance between cell wall (CW) rigidity and flexibility. This can be achieved by a concerted action of peptidoglycan (PG) hydrolases and PG-synthesizing/modifying enzymes. In a search for new regulatory mechanisms responsible for the maintenance of this equilibrium in Lactococcus lactis, we isolated mutants that are resistant to the PG hydrolase lysozyme. We found that 14% of the causative mutations were mapped in the guaA gene, the product of which is involved in purine metabolism. Genetic and transcriptional analyses combined with PG structure determination of the guaA mutant enabled us to reveal the pivotal role of the pyrB gene in the regulation of CW rigidity. Our results indicate that conversion of l-aspartate (l-Asp) to N-carbamoyl-l-aspartate by PyrB may reduce the amount of l-Asp available for PG synthesis and thus cause the appearance of Asp/Asn-less stem peptides in PG. Such stem peptides do not form PG cross-bridges, resulting in a decrease in PG cross-linking and, consequently, reduced PG thickness and rigidity. We hypothesize that the concurrent utilization of l-Asp for pyrimidine and PG synthesis may be part of the regulatory scheme, ensuring CW flexibility during exponential growth and rigidity in stationary phase. The fact that l-Asp availability is dependent on nucleotide metabolism, which is tightly regulated in accordance with the growth rate, provides L. lactis cells the means to ensure optimal CW plasticity without the need to control the expression of PG synthesis genes.
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Affiliation(s)
- Ana Solopova
- From the Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747AG Groningen, The Netherlands
| | - Cécile Formosa-Dague
- Institute of Life Sciences, Université catholique de Louvain, Croix du Sud 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium, and
| | | | | | | | - Christine Péchoux
- Génétique Animale et Biologie Intégrative, Institut National de la Recherche Agronomique, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | | | | | - Jan Kok
- From the Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747AG Groningen, The Netherlands
| | - Pascal Hols
- Institute of Life Sciences, Université catholique de Louvain, Croix du Sud 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium, and
| | - Yves F Dufrêne
- Institute of Life Sciences, Université catholique de Louvain, Croix du Sud 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium, and
| | - Oscar P Kuipers
- From the Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747AG Groningen, The Netherlands
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22
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Identifying protective Streptococcus pyogenes vaccine antigens recognized by both B and T cells in human adults and children. Sci Rep 2016; 6:22030. [PMID: 26911649 PMCID: PMC4766568 DOI: 10.1038/srep22030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/04/2016] [Indexed: 01/01/2023] Open
Abstract
No commercial vaccine exists against Group A streptococci (GAS; Streptococcus pyogenes) and only little is known about anti-GAS protective immunity. In our effort to discover new protective vaccine candidates, we selected 21 antigens based on an in silico evaluation. These were all well-conserved among different GAS strains, upregulated in host-pathogen interaction studies, and predicted to be extracellular or associated with the surface of the bacteria. The antigens were tested for both antibody recognition and T cell responses in human adults and children. The antigenicity of a selected group of antigens was further validated using a high-density peptide array technology that also identified the linear epitopes. Based on immunological recognition, four targets were selected and tested for protective capabilities in an experimental GAS infection model in mice. Shown for the first time, three of these targets (spy0469, spy1228 and spy1801) conferred significant protection whereas one (spy1643) did not.
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23
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Nguyen UT, Harvey H, Hogan AJ, Afonso ACF, Wright GD, Burrows LL. Role of PBPD1 in stimulation of Listeria monocytogenes biofilm formation by subminimal inhibitory β-lactam concentrations. Antimicrob Agents Chemother 2014; 58:6508-17. [PMID: 25136010 PMCID: PMC4249420 DOI: 10.1128/aac.03671-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/10/2014] [Indexed: 12/19/2022] Open
Abstract
Disinfectant-tolerant Listeria monocytogenes biofilms can colonize surfaces that come into contact with food, leading to contamination and, potentially, food-borne illnesses. To better understand the process of L. monocytogenes biofilm formation and dispersal, we screened 1,120 off-patent FDA-approved drugs and identified several that modulate Listeria biofilm development. Among the hits were more than 30 β-lactam antibiotics, with effects ranging from inhibiting (≤50%) to stimulating (≥200%) biofilm formation compared to control. Most β-lactams also dispersed a substantial proportion of established biofilms. This phenotype did not necessarily involve killing, as >50% dispersal could be achieved with concentrations as low as 1/20 of the MIC of some cephalosporins. Penicillin-binding protein (PBP) profiling using a fluorescent penicillin analogue showed similar inhibition patterns for most β-lactams, except that biofilm-stimulatory drugs did not bind PBPD1, a low-molecular-weight d,d-carboxypeptidase. Compared to the wild type, a pbpD1 mutant had an attenuated biofilm response to stimulatory β-lactams. The cephalosporin-responsive CesRK two-component regulatory system, whose regulon includes PBPs, was not required for the response. The requirement for PBPD1 activity for β-lactam stimulation of L. monocytogenes biofilms shows that the specific set of PBPs that are inactivated by a particular drug dictates whether a protective biofilm response is provoked.
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Affiliation(s)
- Uyen T Nguyen
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Hanjeong Harvey
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Andrew J Hogan
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Alexandria C F Afonso
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Gerard D Wright
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences and the Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
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24
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Living biointerfaces based on non-pathogenic bacteria to direct cell differentiation. Sci Rep 2014; 4:5849. [PMID: 25068919 PMCID: PMC5376178 DOI: 10.1038/srep05849] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/07/2014] [Indexed: 01/03/2023] Open
Abstract
Genetically modified Lactococcus lactis, non-pathogenic bacteria expressing the FNIII7-10 fibronectin fragment as a protein membrane have been used to create a living biointerface between synthetic materials and mammalian cells. This FNIII7-10 fragment comprises the RGD and PHSRN sequences of fibronectin to bind α5β1 integrins and triggers signalling for cell adhesion, spreading and differentiation. We used L. lactis strain to colonize material surfaces and produce stable biofilms presenting the FNIII7-10 fragment readily available to cells. Biofilm density is easily tunable and remains stable for several days. Murine C2C12 myoblasts seeded over mature biofilms undergo bipolar alignment and form differentiated myotubes, a process triggered by the FNIII7-10 fragment. This biointerface based on living bacteria can be further modified to express any desired biochemical signal, establishing a new paradigm in biomaterial surface functionalisation for biomedical applications.
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25
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AlKhatib Z, Lagedroste M, Fey I, Kleinschrodt D, Abts A, Smits SHJ. Lantibiotic immunity: inhibition of nisin mediated pore formation by NisI. PLoS One 2014; 9:e102246. [PMID: 25014359 PMCID: PMC4094520 DOI: 10.1371/journal.pone.0102246] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/17/2014] [Indexed: 02/02/2023] Open
Abstract
Nisin, a 3.4 kDa antimicrobial peptide produced by some Lactococcus lactis strains is the most prominent member of the lantibiotic family. Nisin can inhibit cell growth and penetrates the target Gram-positive bacterial membrane by binding to Lipid II, an essential cell wall synthesis precursor. The assembled nisin-Lipid II complex forms pores in the target membrane. To gain immunity against its own-produced nisin, Lactococcus lactis is expressing two immunity protein systems, NisI and NisFEG. Here, we show that the NisI expressing strain displays an IC50 of 73±10 nM, an 8–10-fold increase when compared to the non-expressing sensitive strain. When the nisin concentration is raised above 70 nM, the cells expressing full-length NisI stop growing rather than being killed. NisI is inhibiting nisin mediated pore formation, even at nisin concentrations up to 1 µM. This effect is induced by the C-terminus of NisI that protects Lipid II. Its deletion showed pore formation again. The expression of NisI in combination with externally added nisin mediates an elongation of the chain length of the Lactococcus lactis cocci. While the sensitive strain cell-chains consist mainly of two cells, the NisI expressing cells display a length of up to 20 cells. Both results shed light on the immunity of lantibiotic producer strains, and their survival in high levels of their own lantibiotic in the habitat.
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Affiliation(s)
- Zainab AlKhatib
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Marcel Lagedroste
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Iris Fey
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Diana Kleinschrodt
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - André Abts
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sander H. J. Smits
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- * E-mail:
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26
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Abstract
Bacteria associate with surfaces and one another by elaborating an extracellular matrix to encapsulate cells, creating communities termed biofilms. Biofilms are beneficial in some ecological niches, but also contribute to the pathogenesis of serious and chronic infectious diseases. New approaches and quantitative measurements are needed to define the composition and architecture of bacterial biofilms to help drive the development of strategies to interfere with biofilm assembly. Solid-state NMR is uniquely suited to the examination of insoluble and complex macromolecular and whole-cell systems. This article highlights three examples that implement solid-state NMR to deliver insights into bacterial biofilm composition and changes in cell-wall composition as cells transition to the biofilm lifestyle. Most recently, solid-state NMR measurements provided a total accounting of the protein and polysaccharide components in the extracellular matrix of an E. coli biofilm and transform our qualitative descriptions of matrix composition into chemical parameters that permit quantitative comparisons among samples. We present additional data for whole biofilm samples (cells plus the extracellular matrix) that complement matrix-only analyses. The study of bacterial biofilms by solid-state NMR is an exciting avenue ripe with many opportunities and we close the article by articulating some outstanding questions and future directions in this area.
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Affiliation(s)
| | - Lynette Cegelski
- Department of Chemistry, Stanford University, CA 94305, United States
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Shao C, Sun Y, Wang N, Yu H, Zhou Y, Chen C, Jia J. Changes of proteome components of Helicobacter pylori biofilms induced by serum starvation. Mol Med Rep 2013; 8:1761-6. [PMID: 24100704 DOI: 10.3892/mmr.2013.1712] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 09/26/2013] [Indexed: 11/05/2022] Open
Abstract
Biofilm is the adaptive living mechanism of Helicobacter pylori (H. pylori) during survival and propagation. Nutrient starvation is an environmental pressure for H. pylori in vivo and in vitro. Serum starvation effectively mimics the microenvironment in which H. pylori colonizes healthy humans who carry H. pylori and patients with chronic atrophic gastritis. In addition, it also mimics the in vitro environmental pressures of H. pylori. An H. pylori biofilm was successfully induced with serum starvation. To identify novel proteins associated with biofilm formation at the early stage in H. pylori, high-resolution 2-dimensional gel electrophoresis was performed to obtain the proteome profiles of spiral H. pylori and early biofilm. Differential protein spots were identified using tandem matrix assisted laser desorption ionization time of flight mass spectrometry, which revealed 35 proteins. These proteins are associated with various biological functions, including flagellar movement, bacterial virulence, signal transduction and regulation. To verify the results, the expression of cagA at the mRNA and protein levels was examined by fluorescence quantitative PCR and western blot analysis, respectively. This study indicates that H. pylori form biofilms by initiating multiple mechanisms involving a number of signaling pathways.
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Affiliation(s)
- Chunhong Shao
- Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250012, P.R. China
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Functional screening of a metagenomic library reveals operons responsible for enhanced intestinal colonization by gut commensal microbes. Appl Environ Microbiol 2013; 79:3829-38. [PMID: 23584783 DOI: 10.1128/aem.00581-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Evidence suggests that gut microbes colonize the mammalian intestine through propagation as an adhesive microbial community. A bacterial artificial chromosome (BAC) library of murine bowel microbiota DNA in the surrogate host Escherichia coli DH10B was screened for enhanced adherence capability. Two out of 5,472 DH10B clones, 10G6 and 25G1, exhibited enhanced capabilities to adhere to inanimate surfaces in functional screens. DNA segments inserted into the 10G6 and 25G1 clones were 52 and 41 kb and included 47 and 41 protein-coding open reading frames (ORFs), respectively. DNA sequence alignments, tetranucleotide frequency, and codon usage analysis strongly suggest that these two DNA fragments are derived from species belonging to the genus Bacteroides. Consistent with this finding, a large portion of the predicted gene products were highly homologous to those of Bacteroides spp. Transposon mutagenesis and subsequent experiments that involved heterologous expression identified two operons associated with enhanced adherence. E. coli strains transformed with the 10a or 25b operon adhered to the surface of intestinal epithelium and colonized the mouse intestine more vigorously than did the control strain. This study has revealed the genetic determinants of unknown commensals (probably resembling Bacteroides species) that enhance the ability of the bacteria to colonize the murine bowel.
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Muscariello L, Marino C, Capri U, Vastano V, Marasco R, Sacco M. CcpA and three newly identified proteins are involved in biofilm development in Lactobacillus plantarum. J Basic Microbiol 2012; 53:62-71. [PMID: 22585750 DOI: 10.1002/jobm.201100456] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 11/24/2011] [Indexed: 12/17/2022]
Abstract
The aim of this study was to identify genes involved in biofilm development in the probiotic lactic acid bacterium Lactobacillus plantarum. The ability of L. plantarum LM3 and of some derivative mutant strains to form biofilm has been investigated. Biofilm microtitre plate assays showed that L. plantarum LM3-2, carrying a null mutation in the ccpA gene, coding the CcpA master regulator, was partially impaired in biofilm production compared to wild type (LM3). Moreover, we found three genes in the L. plantarum genome, hereby named flmA, flmB, and flmC, whose deduced amino acid sequences show significant identity with the Streptococcus mutans BrpA (biofilm regulatory protein A). We investigated the role of FlmA, FlmB, and FlmC in biofilm formation by isolating strains carrying null mutations in the corresponding genes. Our results suggest involvement of the Flm proteins in biofilm development. Moreover, transcriptional studies show that expression of flmA, flmB, and flmC is under the control of CcpA. These results, together with the reduced ability of LM3-2 (ccpA1) to form biofilm, strongly suggest a positive role of the master regulator CcpA in biofilm development.
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Affiliation(s)
- Lidia Muscariello
- Dipartimento di Scienze Ambientali, Seconda Università di Napoli, Caserta, Italy
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Hanke ML, Kielian T. Deciphering mechanisms of staphylococcal biofilm evasion of host immunity. Front Cell Infect Microbiol 2012; 2:62. [PMID: 22919653 PMCID: PMC3417388 DOI: 10.3389/fcimb.2012.00062] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 04/20/2012] [Indexed: 12/19/2022] Open
Abstract
Biofilms are adherent communities of bacteria contained within a complex matrix. Although host immune responses to planktonic staphylococcal species have been relatively well-characterized, less is known regarding immunity to staphylococcal biofilms and how they modulate anti-bacterial effector mechanisms when organized in this protective milieu. Previously, staphylococcal biofilms were thought to escape immune recognition on the basis of their chronic and indolent nature. Instead, we have proposed that staphylococcal biofilms skew the host immune response away from a proinflammatory bactericidal phenotype toward an anti-inflammatory, pro-fibrotic response that favors bacterial persistence. This possibility is supported by recent studies from our laboratory using a mouse model of catheter-associated biofilm infection, where S. aureus biofilms led to the accumulation of alternatively activated M2 macrophages that exhibit anti-inflammatory and pro-fibrotic properties. In addition, relatively few neutrophils were recruited into S. aureus biofilms, representing another mechanism that deviates from planktonic infections. However, it is important to recognize the diversity of biofilm infections, in that studies by others have demonstrated the induction of distinct immune responses during staphylococcal biofilm growth in other models, suggesting influences from the local tissue microenvironment. This review will discuss the immune defenses that staphylococcal biofilms evade as well as conceptual issues that remain to be resolved. An improved understanding of why the host immune response is unable to clear biofilm infections could lead to targeted therapies to reverse these defects and expedite biofilm clearance.
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Affiliation(s)
| | - Tammy Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, OmahaNE, USA
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31
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Liu W, Dong N, Zhang XH. Overexpression of mltA in Edwardsiella tarda reduces resistance to antibiotics and enhances lethality in zebra fish. J Appl Microbiol 2012; 112:1075-85. [PMID: 22443589 DOI: 10.1111/j.1365-2672.2012.05291.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIMS The aim of this study was to investigate the role of membrane-bound lytic murein transglycosylase A (MltA) in a bacterial fish pathogen Edwardsiella tarda. METHODS AND RESULTS An mltA in-frame deletion mutant (ΔmltA) and an mltA overexpression strain (mltA(+)) of Edw. tarda were constructed through double-crossover allelic exchange and by transformation of a low-copy plasmid carrying the intact mltA into the ΔmltA mutant, respectively. Either inactivation or overexpression of MltA in Edw. tarda resulted in elevated sensitivity to β-lactam antibiotics and lower viability in oligotrophic or high osmotic environment than wild-type strain. Autolysis induced by EDTA was reduced in ΔmltA strain, while mltA(+) strain was virtually flimsy, indicating that MltA is responsible for the lysis effect. Moreover, mltA(+) strain exhibited significant increases in lipopolysaccharide (LPS) biosynthesis and virulence to zebra fish compared with wild-type strain. CONCLUSIONS The results indicated that MltA plays essential roles in β-lactam antibiotics and environmental stresses resistance, autolysis, LPS biosynthesis and pathogenicity of Edw. tarda. This is the first report that MltA has a virulence-related function in Edw. tarda. SIGNIFICANCE AND IMPACT OF THE STUDY This study provided useful information for further studies on pathogenesis of Edw. tarda.
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Affiliation(s)
- W Liu
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
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32
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Geng J, Chiu CH, Tang P, Chen Y, Shieh HR, Hu S, Chen YYM. Complete genome and transcriptomes of Streptococcus parasanguinis FW213: phylogenic relations and potential virulence mechanisms. PLoS One 2012; 7:e34769. [PMID: 22529932 PMCID: PMC3329508 DOI: 10.1371/journal.pone.0034769] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/05/2012] [Indexed: 01/13/2023] Open
Abstract
Streptococcus parasanguinis, a primary colonizer of the tooth surface, is also an opportunistic pathogen for subacute endocarditis. The complete genome of strain FW213 was determined using the traditional shotgun sequencing approach and further refined by the transcriptomes of cells in early exponential and early stationary growth phases in this study. The transcriptomes also discovered 10 transcripts encoding known hypothetical proteins, one pseudogene, five transcripts matched to the Rfam and additional 87 putative small RNAs within the intergenic regions defined by the GLIMMER analysis. The genome contains five acquired genomic islands (GIs) encoding proteins which potentially contribute to the overall pathogenic capacity and fitness of this microbe. The differential expression of the GIs and various open reading frames outside the GIs at the two growth phases suggested that FW213 possess a range of mechanisms to avoid host immune clearance, to colonize host tissues, to survive within oral biofilms and to overcome various environmental insults. Furthermore, the comparative genome analysis of five S. parasanguinis strains indicates that albeit S. parasanguinis strains are highly conserved, variations in the genome content exist. These variations may reflect differences in pathogenic potential between the strains.
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Affiliation(s)
- Jianing Geng
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Cheng-Hsun Chiu
- Division of Pediatric Infectious Diseases, Molecular Infectious Disease Research Center, Chang Gung Children's Hospital, Tao-Yuan, Taiwan
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Tao-Yuan, Taiwan
| | - Petrus Tang
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- Bioinformatics Center, Chang Gung University, Tao-Yuan, Taiwan
| | - Yaping Chen
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- Graduate University of the Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Hui-Ru Shieh
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- Department of Microbiology and Immunology, Chang Gung University, Tao-Yuan, Taiwan
| | - Songnian Hu
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Yi-Ywan M. Chen
- Graduate Institute of Basic Medical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- Department of Microbiology and Immunology, Chang Gung University, Tao-Yuan, Taiwan
- * E-mail:
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33
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Maeda T, Yoshimura T, García-Contreras R, Ogawa HI. Purification and characterization of a serine protease secreted by Brevibacillus sp. KH3 for reducing waste activated sludge and biofilm formation. BIORESOURCE TECHNOLOGY 2011; 102:10650-10656. [PMID: 21925876 DOI: 10.1016/j.biortech.2011.08.098] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 08/22/2011] [Accepted: 08/22/2011] [Indexed: 05/31/2023]
Abstract
A novel protease secreted by Brevibacillus sp. KH3 isolated from excess sludge at 50 °C and used as a sludge-lysing strain was investigated in this study. Sludge reduction was minimized by protease inhibitors and a 40-kDa protease, which significantly contributed to this sludge-reducing activity, was purified as the target protein. The final purified protease demonstrated 92-fold higher specific activity than the initial crude extracts. The sludge-reducing efficiency deteriorated relative to decreased protease activity triggered by EDTA; thus, the purified protease was a causative agent in reducing excess sludge. The 40-kDa protease was a serine metalloprotease and showed the highest activity at 50 °C and pH 8.0, and the activity was enhanced in the presence of calcium ions, indicating that the purified protease contained calcium ion. Furthermore, this 40-kDa protease inhibited biofilm formation in excess sludge. These results imply that sludge reduction is because of reduction of biofilm formation in excess sludge.
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Affiliation(s)
- Toshinari Maeda
- Department of Biological Functions and Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu 808-0196, Japan.
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34
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Okamoto A, Hasegawa T, Yamada K, Ohta M. Application of both high-performance liquid chromatography combined with tandem mass spectrometry shotgun and 2-D polyacrylamide gel electrophoresis for streptococcal exoproteins gave reliable proteomic data. Microbiol Immunol 2011; 55:84-94. [PMID: 21204954 DOI: 10.1111/j.1348-0421.2010.00302.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Streptococci secrete a large number of exoproteins including virulence-associated toxins and enzymes. To construct a reliable database of streptococcal exoproteins, we integrated the results that were derived from two approaches: LC-based shotgun proteomic analysis and 2-D PAGE-based proteomic analysis. We identified 74 and 82 proteins by LC-based and gel-based analysis, respectively. Forty-five proteins were identified by both methods. In addition, two proteins, one identified by both methods and the other only by LC-based shotgun analysis, were newly annotated. We therefore found the importance of combinational analysis by the two methods for the construction of a more reliable database.
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Affiliation(s)
- Akira Okamoto
- Department of Bacteriology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan
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35
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Thurlow LR, Hanke ML, Fritz T, Angle A, Aldrich A, Williams SH, Engebretsen IL, Bayles KW, Horswill AR, Kielian T. Staphylococcus aureus biofilms prevent macrophage phagocytosis and attenuate inflammation in vivo. THE JOURNAL OF IMMUNOLOGY 2011; 186:6585-96. [PMID: 21525381 DOI: 10.4049/jimmunol.1002794] [Citation(s) in RCA: 464] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Biofilms are complex communities of bacteria encased in a matrix composed primarily of polysaccharides, extracellular DNA, and protein. Staphylococcus aureus can form biofilm infections, which are often debilitating due to their chronicity and recalcitrance to antibiotic therapy. Currently, the immune mechanisms elicited during biofilm growth and their impact on bacterial clearance remain to be defined. We used a mouse model of catheter-associated biofilm infection to assess the functional importance of TLR2 and TLR9 in the host immune response during biofilm formation, because ligands for both receptors are present within the biofilm. Interestingly, neither TLR2 nor TLR9 impacted bacterial density or inflammatory mediator secretion during biofilm growth in vivo, suggesting that S. aureus biofilms circumvent these traditional bacterial recognition pathways. Several potential mechanisms were identified to account for biofilm evasion of innate immunity, including significant reductions in IL-1β, TNF-α, CXCL2, and CCL2 expression during biofilm infection compared with the wound healing response elicited by sterile catheters, limited macrophage invasion into biofilms in vivo, and a skewing of the immune response away from a microbicidal phenotype as evidenced by decreases in inducible NO synthase expression concomitant with robust arginase-1 induction. Coculture studies of macrophages with S. aureus biofilms in vitro revealed that macrophages successful at biofilm invasion displayed limited phagocytosis and gene expression patterns reminiscent of alternatively activated M2 macrophages. Collectively, these findings demonstrate that S. aureus biofilms are capable of attenuating traditional host proinflammatory responses, which may explain why biofilm infections persist in an immunocompetent host.
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Affiliation(s)
- Lance R Thurlow
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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The major autolysin of Streptococcus gordonii is subject to complex regulation and modulates stress tolerance, biofilm formation, and extracellular-DNA release. J Bacteriol 2011; 193:2826-37. [PMID: 21478346 DOI: 10.1128/jb.00056-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A gene, designated atlS, encoding a major autolysin from Streptococcus gordonii, was identified and characterized. The predicted AtlS protein is 1,160 amino acids and 127 kDa and has a conserved β1,4-N-acetylmuramidase domain. Zymographic analysis of wild-type S. gordonii revealed peptidoglycan hydrolase activities with molecular masses of 130 and 90 kDa that were absent in an atlS deletion mutant. Western blotting revealed that the 90-kDa band was derived from the 130-kDa protein. Inactivation of atlS resulted in formation of long chains by the cells, markedly decreased autolytic capacity, poor biofilm formation, diminished tolerance of acid and oxidative stress, and decreased production of extracellular DNA (eDNA). The biofilm-forming capacity of the atlS mutant could be almost completely restored to that of the wild-type strain by adding purified recombinant AtlA autolysin of S. mutans but was only partially restored by addition of eDNA. Autolysis, eDNA release, and atlS expression increased sharply when cells entered stationary phase and were greatly enhanced in cells growing with aeration. The LytST and VicRK two-component systems were both required for the induction of atlS by aeration, and purified LytT was able to bind to the promoter region of atlS in vitro. Thus, AtlS and its associated regulatory cascade dominantly control phenotypes of S. gordonii that are critical to colonization, persistence, and competition with other commensal and pathogenic oral bacteria in response to the redox environment and growth domain.
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Parti RP, Biswas D, Helgeson S, Michael FS, Cox A, Dillon JAR. Attenuated virulence of min operon mutants of Neisseria gonorrhoeae and their interactions with human urethral epithelial cells. Microbes Infect 2011; 13:545-54. [PMID: 21315173 DOI: 10.1016/j.micinf.2011.01.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 11/29/2022]
Abstract
Neisseria gonorrhoeae, a sexually-transmitted gram-negative bacterium, causes gonorrhoea in humans. The min genes of N. gonorrhoeae are involved in cell division site selection with oxyR co-transcribed with these genes. The mutation in min genes and oxy R cause aberrant cell morphology and aggregation patterns, respectively. Our objective was to assess the contribution of neisserial min operon cell division genes i.e. minC, minD and oxyR in virulence. Compared to the N. gonorrhoeae parental strain (Ng CH811Str(R)), its isogenic mutants with insertionally inactivated minC (Ng CSRC1), minD (Ng CJSD1) or oxyR (Ng KB1) showed reduced adherence to and invasion of urethral epithelial cells. This may be explained by defective microcolony formation in the mutant strains, possibly owing to abnormal morphology and aggregation. The expression levels of surface virulence factors like Opa, pilin and lipooligosaccharide in the mutants were unchanged relative to Ng CH811Str(R). Furthermore, in urethral epithelial cells, the min and oxyR mutants induced the release of proinflammatory cytokines like IL6 and IL8 to levels similar to that induced by the parental strain. Taken together, our studies indicate that inactivation of minC, minD or oxyR in N. gonorrhoeae attenuates its ability to bind to and invade urethral epithelial cells without altering its potential to induce IL6 and IL8 release.
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Affiliation(s)
- Rajinder P Parti
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada
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38
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Pérez-Núñez D, Briandet R, David B, Gautier C, Renault P, Hallet B, Hols P, Carballido-López R, Guédon E. A new morphogenesis pathway in bacteria: unbalanced activity of cell wall synthesis machineries leads to coccus-to-rod transition and filamentation in ovococci. Mol Microbiol 2010; 79:759-71. [PMID: 21255117 DOI: 10.1111/j.1365-2958.2010.07483.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacteria display a variety of shapes, which have biological relevance. In most eubacteria, cell shape is maintained by the tough peptidoglycan (PG) layer of the cell wall, the sacculus. The organization of PG synthesis machineries, orchestrated by different cytoskeletal elements, determines the specific shapes of sacculi. In rod-shaped bacteria, the actin-like (MreB) and the tubuline-like (FtsZ) cytoskeletons control synthesis of the sidewall (elongation) and the crosswall (septation) respectively. Much less is known concerning cell morphogenesis in cocci, which lack MreB proteins. While spherical cocci exclusively display septal growth, ovococci additionally display peripheral growth, which is responsible of the slight longitudinal expansion that generates their ovoid shape. Here, we report that the ovococcus Lactococcus lactis has the ability to become rod-shaped. L. lactis IL1403 wild-type cells form long aseptate filaments during both biofilm and planktonic growth in a synthetic medium. Nascent PG insertion and the division protein FtsK localize in multiple peripheral rings regularly spaced along the filaments. We show that filamentation results from septation inhibition, and that penicillin-binding proteins PBP2x and PBP2b play a direct role in this process. We propose a model for filament formation in L. lactis, and discuss the possible biological role of such morphological differentiation.
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Affiliation(s)
- Daniel Pérez-Núñez
- INRA, UMR1319 Micalis, Domaine de Vilvert, F-78352 Jouy-en-Josas, France
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Kylä-Nikkilä K, Alakuijala U, Saris PEJ. Immobilization of Lactococcus lactis to cellulosic material by cellulose-binding domain of Cellvibrio japonicus. J Appl Microbiol 2010; 109:1274-83. [PMID: 20497279 DOI: 10.1111/j.1365-2672.2010.04757.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIMS Immobilization of whole cells can be used to accumulate cells in a bioreactor and thus increase the cell density and potentially productivity, also. Cellulose is an excellent matrix for immobilization purposes because it does not require chemical modifications and is commercially available in many different forms at low price. The aim of this study was to construct a Lactococcus lactis strain capable of immobilizing to a cellulosic matrix. METHODS AND RESULTS In this study, the Usp45 signal sequence fused with the cellulose-binding domain (CBD) (112 amino acids) of XylA enzyme from Cellvibrio japonicus was fused with PrtP or AcmA anchors derived from L. lactis. A successful surface display of L. lactis cells expressing these fusion proteins under the P45 promoter was achieved and detected by whole-cell ELISA. A rapid filter paper assay was developed to study the cellulose-binding capability of these recombinant strains. As a result, an efficient immobilization to filter paper was demonstrated for the L. lactis cells expressing the CBD-fusion protein. The highest immobilization (92%) was measured for the strain expressing the CBD in fusion with the 344 amino acid PrtP anchor. CONCLUSIONS The result from the binding tests indicated that a new phenotype for L. lactis with cellulose-binding capability was achieved with both PrtP (LPXTG type anchor) and AcmA (LysM type anchor) fusions with CBD. SIGNIFICANCE AND IMPACT OF THE STUDY We demonstrated that an efficient immobilization of recombinant L. lactis cells to cellulosic matrix is possible. This is a step forward in developing efficient immobilization systems for lactococcal strains for industrial-scale fermentations.
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Affiliation(s)
- K Kylä-Nikkilä
- Department of Applied Chemistry and Microbiology, Division of Microbiology, University of Helsinki, Helsinki, Finland
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Ahn SJ, Rice KC, Oleas J, Bayles KW, Burne RA. The Streptococcus mutans Cid and Lrg systems modulate virulence traits in response to multiple environmental signals. MICROBIOLOGY-SGM 2010; 156:3136-3147. [PMID: 20671018 PMCID: PMC3068699 DOI: 10.1099/mic.0.039586-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The tight control of autolysis by Streptococcus mutans is critical for proper virulence gene expression and biofilm formation. A pair of dicistronic operons, SMU.575/574 (lrgAB) and SMU.1701/1700 (designated cidAB), encode putative membrane proteins that share structural features with the bacteriophage-encoded holin family of proteins, which modulate host cell lysis during lytic infection. Analysis of S. mutans lrg and cid mutants revealed a role for these operons in autolysis, biofilm formation, glucosyltransferase expression and oxidative stress tolerance. Expression of lrgAB was repressed during early exponential phase and was induced over 1000-fold as cells entered late exponential phase, whereas cidAB expression declined from early to late exponential phase. A two-component system encoded immediately upstream of lrgAB (LytST) was required for activation of lrgAB expression, but not for cid expression. In addition to availability of oxygen, glucose levels were revealed to affect lrg and cid transcription differentially and significantly, probably through CcpA (carbon catabolite protein A). Collectively, these findings demonstrate that the Cid/Lrg system can affect several virulence traits of S. mutans, and its expression is controlled by two major environmental signals, oxygen and glucose. Moreover, cid/lrg expression is tightly regulated by LytST and CcpA.
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Affiliation(s)
- Sang-Joon Ahn
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
| | - Kelly C. Rice
- Department of Microbiology and Cell Science, College of Agricultural and Life Sciences, University of Florida, Gainesville, FL 32610, USA
| | - Janneth Oleas
- Department of Microbiology and Cell Science, College of Agricultural and Life Sciences, University of Florida, Gainesville, FL 32610, USA
| | - Kenneth W. Bayles
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Robert A. Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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Chapot-Chartier MP, Vinogradov E, Sadovskaya I, Andre G, Mistou MY, Trieu-Cuot P, Furlan S, Bidnenko E, Courtin P, Péchoux C, Hols P, Dufrêne YF, Kulakauskas S. Cell surface of Lactococcus lactis is covered by a protective polysaccharide pellicle. J Biol Chem 2010; 285:10464-71. [PMID: 20106971 DOI: 10.1074/jbc.m109.082958] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Gram-positive bacteria, the functional role of surface polysaccharides (PS) that are not of capsular nature remains poorly understood. Here, we report the presence of a novel cell wall PS pellicle on the surface of Lactococcus lactis. Spontaneous PS-negative mutants were selected using semi-liquid growth conditions, and all mutations were mapped in a single chromosomal locus coding for PS biosynthesis. PS molecules were shown to be composed of hexasaccharide phosphate repeating units that are distinct from other bacterial PS. Using complementary atomic force and transmission electron microscopy techniques, we showed that the PS layer forms an outer pellicle surrounding the cell. Notably, we found that this cell wall layer confers a protective barrier against host phagocytosis by murine macrophages. Altogether, our results suggest that the PS pellicle could represent a new cell envelope structural component of Gram-positive bacteria.
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Genetic features of resident biofilms determine attachment of Listeria monocytogenes. Appl Environ Microbiol 2009; 75:7814-21. [PMID: 19837841 DOI: 10.1128/aem.01333-09] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Planktonic Listeria monocytogenes cells in food-processing environments tend most frequently to adhere to solid surfaces. Under these conditions, they are likely to encounter resident biofilms rather than a raw solid surface. Although metabolic interactions between L. monocytogenes and resident microflora have been widely studied, little is known about the biofilm properties that influence the initial fixation of L. monocytogenes to the biofilm interface. To study these properties, we created a set of model resident Lactococcus lactis biofilms with various architectures, types of matrices, and individual cell surface properties. This was achieved using cell wall mutants that affect bacterial chain formation, exopolysaccharide (EPS) synthesis and surface hydrophobicity. The dynamics of the formation of these biofilm structures were analyzed in flow cell chambers using in situ time course confocal laser scanning microscopy imaging. All the L. lactis biofilms tested reduced the initial immobilization of L. monocytogenes compared to the glass substratum of the flow cell. Significant differences were seen in L. monocytogenes settlement as a function of the genetic background of resident lactococcal biofilm cells. In particular, biofilms of the L. lactis chain-forming mutant resulted in a marked increase in L. monocytogenes settlement, while biofilms of the EPS-secreting mutant efficiently prevented pathogen fixation. These results offer new insights into the role of resident biofilms in governing the settlement of pathogens on food chain surfaces and could be of relevance in the field of food safety controls.
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Niderkorn V, Morgavi D, Aboab B, Lemaire M, Boudra H. Cell wall component and mycotoxin moieties involved in the binding of fumonisin B1and B2by lactic acid bacteria. J Appl Microbiol 2009; 106:977-85. [DOI: 10.1111/j.1365-2672.2008.04065.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Interconnections between Sigma B, agr, and proteolytic activity in Staphylococcus aureus biofilm maturation. Infect Immun 2009; 77:1623-35. [PMID: 19188357 DOI: 10.1128/iai.01036-08] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus is a proficient biofilm former on host tissues and medical implants. We mutagenized S. aureus strain SH1000 to identify loci essential for ica-independent mechanisms of biofilm maturation and identified multiple insertions in the rsbUVW-sigB operon. Following construction and characterization of a sigB deletion, we determined that the biofilm phenotype was due to a lack of sigma factor B (SigB) activity. The phenotype was conserved in a sigB mutant of USA300 strain LAC, a well-studied community-associated methicillin-resistant S. aureus isolate. We determined that agr RNAIII levels were elevated in the sigB mutants, and high levels of RNAIII expression are known to have antibiofilm effects. By introducing an agr mutation into the SH1000 or LAC sigB deletion strain, S. aureus regained biofilm capacity, indicating that the biofilm phenotype was agr dependent. Protease activity is linked to agr activity and ica-independent biofilm formation, and we observed that the protease inhibitors phenylmethylsulfonyl fluoride and alpha-macroglobulin could reverse the sigB biofilm defect. Similarly, inactivating genes encoding both the aureolysin and Spl extracellular proteases in the sigB mutant restored biofilm capacity. Due to the growing link between murein hydrolase activity and biofilm maturation, autolysin zymography was performed, which revealed an altered profile in the sigB mutant; again, the phenotype could be repaired through protease inactivation. These findings indicate that the lack of SigB activity results in increased RNAIII expression, thus elevating extracellular protease levels and altering the murein hydrolase activity profile. Altogether, our observations demonstrate that SigB is an essential regulator of S. aureus biofilm maturation.
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Giaouris E, Chapot-Chartier MP, Briandet R. Surface physicochemical analysis of natural Lactococcus lactis strains reveals the existence of hydrophobic and low charged strains with altered adhesive properties. Int J Food Microbiol 2008; 131:2-9. [PMID: 18954916 DOI: 10.1016/j.ijfoodmicro.2008.09.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 08/20/2008] [Accepted: 09/09/2008] [Indexed: 11/17/2022]
Abstract
The cell surface physicochemical properties of 50 Lactococcus lactis strains of different subspecies and isolated from different origins (dairy, vegetal and animal) were examined. Cell surface hydrophobicity and Lewis acid-base properties were evaluated by affinity measurements to solvents in a partitioning test, while the global electrical charge of the cells was assessed by micro-electrophoresis using a laser zeta-meter. A global multivariate analysis of the results revealed a high natural diversity of L. lactis cell surface properties. While 52% of the strains present a hydrophilic and electronegative cell wall surface, a group of strikingly hydrophobic strains (12% of the strains) and a group of strains with unusual low charged surface (18%) were identified. Adhesion on polystyrene microtitre plates was evaluated for twelve strains selected from the multivariate analysis as representatives of the various observed cell wall surface physicochemical patterns. A significant correlation between adhesion, hydrophobicity and low electronegativity was observed when adhesion was performed in a low ionic strength suspending medium. The most adhesive strains were hydrophobic or low charged. The presence of repulsive electrostatic interactions led to a decrease in adhesion of the most negatively charged hydrophilic strains. The present study highlights the diversity of L. lactis cell surface physicochemical properties, diversity that could not be connected to the origin or to the subspecies of the strains.
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Affiliation(s)
- Efstathios Giaouris
- Unité mixte de recherche en Bioadhesion et Hygiène des Matériaux, UMR 763 INRA-AgroParisTech, 25 avenue de la République, 91300 Massy, France
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Variations in the degree of D-Alanylation of teichoic acids in Lactococcus lactis alter resistance to cationic antimicrobials but have no effect on bacterial surface hydrophobicity and charge. Appl Environ Microbiol 2008; 74:4764-7. [PMID: 18539809 DOI: 10.1128/aem.00078-08] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An increase of the degree of d-alanylation of teichoic acids in Lactococcus lactis resulted in a significant increase of bacterial resistance toward the cationic antimicrobials nisin and lysozyme, whereas the absence of D-alanylation led to a decreased resistance toward the same compounds. In contrast, the same variations of the D-alanylation degree did not modify bacterial cell surface charge and hydrophobicity. Bacterial adhesion to polystyrene and glass surfaces was not modified either.
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Vollmer W, Joris B, Charlier P, Foster S. Bacterial peptidoglycan (murein) hydrolases. FEMS Microbiol Rev 2008; 32:259-86. [PMID: 18266855 DOI: 10.1111/j.1574-6976.2007.00099.x] [Citation(s) in RCA: 609] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Most bacteria have multiple peptidoglycan hydrolases capable of cleaving covalent bonds in peptidoglycan sacculi or its fragments. An overview of the different classes of peptidoglycan hydrolases and their cleavage sites is provided. The physiological functions of these enzymes include the regulation of cell wall growth, the turnover of peptidoglycan during growth, the separation of daughter cells during cell division and autolysis. Specialized hydrolases enlarge the pores in the peptidoglycan for the assembly of large trans-envelope complexes (pili, flagella, secretion systems), or they specifically cleave peptidoglycan during sporulation or spore germination. Moreover, peptidoglycan hydrolases are involved in lysis phenomena such as fratricide or developmental lysis occurring in bacterial populations. We will also review the current view on the regulation of autolysins and on the role of cytoplasm hydrolases in peptidoglycan recycling and induction of beta-lactamase.
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Affiliation(s)
- Waldemar Vollmer
- Institute for Cell and Molecular Biosciences, University of Newcastle upon Tyne, Newcastle upon Tyne, UK.
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Abstract
Oxygen profoundly affects the composition of oral biofilms. Recently, we showed that exposure of Streptococcus mutans to oxygen strongly inhibits biofilm formation and alters cell surface biogenesis. To begin to dissect the underlying mechanisms by which oxygen affects known virulence traits of S. mutans, transcription profiling was used to show that roughly 5% of the genes of this organism are differentially expressed in response to aeration. Among the most profoundly upregulated genes were autolysis-related genes and those that encode bacteriocins, the ClpB protease chaperone subunit, pyruvate dehydrogenase, the tricarboxylic acid cycle enzymes, NADH oxidase enzymes, and certain carbohydrate transporters and catabolic pathways. Consistent with our observation that the ability of S. mutans to form biofilms was severely impaired by oxygen exposure, transcription of the gtfB gene, which encodes one of the primary enzymes involved in the production of water-insoluble, adhesive glucan exopolysaccharides, was down-regulated in cells growing aerobically. Further investigation revealed that transcription of gtfB, but not gtfC, was responsive to oxygen and that aeration causes major changes in the amount and degree of cell association of the Gtf enzymes. Moreover, inactivation of the VicK sensor kinase affected the expression and localization the GtfB and GtfC enzymes. This study provides novel insights into the complex transcriptional and posttranscriptional regulatory networks used by S. mutans to modulate virulence gene expression and exopolysaccharide production in response to changes in oxygen availability.
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Ahn SJ, Burne RA. Effects of oxygen on biofilm formation and the AtlA autolysin of Streptococcus mutans. J Bacteriol 2007; 189:6293-302. [PMID: 17616606 PMCID: PMC1951938 DOI: 10.1128/jb.00546-07] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Streptococcus mutans atlA gene encodes an autolysin required for biofilm maturation and biogenesis of a normal cell surface. We found that the capacity to form biofilms by S. mutans, one of the principal causative agents of dental caries, was dramatically impaired by growth of the organism in an aerated environment and that cells exposed to oxygen displayed marked changes in surface protein profiles. Inactivation of the atlA gene alleviated repression of biofilm formation in the presence of oxygen. Also, the formation of long chains, a characteristic of AtlA-deficient strains, was less evident in cells grown with aeration. The SMu0629 gene is immediately upstream of atlA and encodes a product that contains a C-X-X-C motif, a characteristic of thiol-disulfide oxidoreductases. Inactivation of SMu0629 significantly reduced the levels of AtlA protein and led to resistance to autolysis. The SMu0629 mutant also displayed an enhanced capacity to form biofilms in the presence of oxygen compared to that of the parental strain. The expression of SMu0629 was shown to be under the control of the VicRK two-component system, which influences oxidative stress tolerance in S. mutans. Disruption of vicK also led to inhibition of processing of AtlA, and the mutant was hyperresistant to autolysis. When grown under aerobic conditions, the vicK mutant also showed significantly increased biofilm formation compared to strain UA159. This study illustrates the central role of AtlA and VicK in orchestrating growth on surfaces and envelope biogenesis in response to redox conditions.
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Affiliation(s)
- Sang-Joon Ahn
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL 32610, USA
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Veiga P, Bulbarela-Sampieri C, Furlan S, Maisons A, Chapot-Chartier MP, Erkelenz M, Mervelet P, Noirot P, Frees D, Kuipers OP, Kok J, Gruss A, Buist G, Kulakauskas S. SpxB Regulates O-Acetylation-dependent Resistance of Lactococcus lactis Peptidoglycan to Hydrolysis. J Biol Chem 2007; 282:19342-54. [PMID: 17485463 DOI: 10.1074/jbc.m611308200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endogenous peptidoglycan (PG)-hydrolyzing enzymes, the autolysins, are needed to relax the rigid PG sacculus to allow bacterial cell growth and separation. PGs of pathogens and commensal bacteria may also be degraded by hydrolases of animal origin (lysozymes), which act as antimicrobials. The genetic mechanisms regulating PG resistance to hydrolytic degradation were dissected in the Gram-positive bacterium Lactococcus lactis. We found that the ability of L. lactis to counteract PG hydrolysis depends on the degree of acetylation. Overexpression of PG O-acetylase (encoded by oatA) led to bacterial growth arrest, indicating the potential lethality of oatA and a need for its tight regulation. A novel regulatory factor, SpxB (previously denoted as YneH), exerted a positive effect on oatA expression. Our results indicate that SpxB binding to RNA polymerase constitutes a previously missing link in the multistep response to cell envelope stress, provoked by PG hydrolysis with lysozyme. We suggest that the two-component system CesSR responds to this stress by inducing SpxB, thus favoring its interactions with RNA polymerase. Induction of PG O-acetylation by this cascade renders it resistant to hydrolysis.
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Affiliation(s)
- Patrick Veiga
- Unité Bactéries Lactiques et Pathogènes Opportunistes, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas Cedex, France
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