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Elpers L, Lüken L, Lange F, Hensel M. Factors Required for Adhesion of Salmonella enterica Serovar Typhimurium to Lactuca sativa (Lettuce). Microbiol Spectr 2023; 11:e0343622. [PMID: 36533955 PMCID: PMC9927257 DOI: 10.1128/spectrum.03436-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is a major cause of foodborne gastroenteritis. Recent outbreaks of infections by S. enterica serovar Typhimurium are often associated with non-animal-related food, i.e., vegetables, fruits, herbs, sprouts, and nuts. One main problem related to the consumption of fresh produce is the minimal processing, especially for leafy green salads. In this study, we focused on butterhead lettuce (Lactuca sativa) to which S. enterica serovar Typhimurium adheres at higher rates compared to Valerianella locusta, resulting in prolonged persistence. Here, we systematically analyzed factors contributing to adhesion of S. enterica serovar Typhimurium to L. sativa leaves. Application of a reductionist, synthetic approach, including the controlled surface expression of specific adhesive structures of S. enterica serovar Typhimurium, one at a time, enabled the identification of relevant fimbrial and nonfimbrial adhesins, the O-antigen of lipopolysaccharide, the flagella, and chemotaxis being involved in binding to L. sativa leaves. The analyses revealed contributions of Lpf fimbriae, Sti fimbriae, autotransported adhesin MisL, T1SS-secreted BapA, intact lipopolysaccharide (LPS), and flagella-mediated motility to adhesion of S. enterica serovar Typhimurium to L. sativa leaves. In addition, we identified BapA as a potential adhesin involved in binding to V. locusta and L. sativa leaf surfaces. IMPORTANCE The number of produce-associated outbreaks by gastrointestinal pathogens is increasing and underlines the relevance to human health. The mechanisms involved in the colonization of, persistence on, and transmission by, fresh produce are poorly understood. Here, we investigated the contribution of adhesive factors of S. enterica serovar Typhimurium in the initial phase of plant colonization, i.e., the binding to the plant surface. We used the previously established reductionist, synthetic approach to identify factors that contribute to the surface binding of S. enterica serovar Typhimurium to leaves of L. sativa by expressing all known adhesive structures by remote control expression system.
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Affiliation(s)
- Laura Elpers
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Lena Lüken
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Fabio Lange
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- Center for Cellular Nanoanalytics (CellNanOs), Universität Osnabrück, Osnabrück, Germany
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2
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Flagellar Phenotypes Impact on Bacterial Transport and Deposition Behavior in Porous Media: Case of Salmonella enterica Serovar Typhimurium. Int J Mol Sci 2022; 23:ijms232214460. [PMID: 36430938 PMCID: PMC9698738 DOI: 10.3390/ijms232214460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/11/2022] [Accepted: 11/16/2022] [Indexed: 11/23/2022] Open
Abstract
Bacterial contamination of groundwater has always been an ecological problem worthy of attention. In this study, Salmonella enterica serovar Typhimurium with different flagellar phenotypes mainly characterized during host-pathogen interaction were analyzed for their transport and deposition behavior in porous media. Column transport experiments and a modified mobile-immobile model were applicated on different strains with flagellar motility (wild-type) or without motility (ΔmotAB), without flagella (ΔflgKL), methylated and unmethylated flagellin (ΔfliB), and different flagella phases (fliCON, fljBON). Results showed that flagella motility could promote bacterial transport and deposition due to their biological advantages of moving and attaching to surfaces. We also found that the presence of non-motile flagella improved bacterial adhesion according to a higher retention rate of the ΔmotAB strain compared to the ΔflgKL strain. This indicated that bacteria flagella and motility both had promoting effects on bacterial deposition in sandy porous media. Flagella phases influenced the bacterial movement; the fliCON strain went faster through the column than the fljBON strain. Moreover, flagella methylation was found to favor bacterial transport and deposition. Overall, flagellar modifications affect Salmonella enterica serovar Typhimurium transport and deposition behavior in different ways in environmental conditions.
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Elpers L, Deiwick J, Hensel M. Effect of Environmental Temperatures on Proteome Composition of Salmonella enterica Serovar Typhimurium. Mol Cell Proteomics 2022; 21:100265. [PMID: 35788066 PMCID: PMC9396072 DOI: 10.1016/j.mcpro.2022.100265] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 06/17/2022] [Accepted: 06/30/2022] [Indexed: 12/29/2022] Open
Abstract
Salmonella enterica serovar Typhimurium (STM) is a major cause of gastroenteritis and transmitted by consumption of contaminated food. STM is associated to food originating from animals (pork, chicken, eggs) or plants (vegetables, fruits, nuts, and herbs). Infection of warm-blooded mammalian hosts by STM and the underlying complex regulatory network of virulence gene expression depend on various environmental conditions encountered in hosts. However, less is known about the proteome and possible regulatory networks for gene expression of STM outside the preferred host. Nutritional limitations and changes in temperature are the most obvious stresses outside the native host. Thus, we analyzed the proteome profile of STM grown in rich medium (LB medium) or minimal medium (PCN medium) at temperatures ranging from 8 °C to 37 °C. LB medium mimics the nutritional rich environment inside the host, whereas minimal PCN medium represents nutritional limitations outside the host, found during growth of fresh produce (field conditions). Further, the range of temperatures analyzed reflects conditions within natural hosts (37 °C), room temperature (20 °C), during growth under agricultural conditions (16 °C and 12 °C), and during food storage (8 °C). Implications of altered nutrient availability and growth temperature on STM proteomes were analyzed by HPLC/MS-MS and label-free quantification. Our study provides first insights into the complex adaptation of STM to various environmental temperatures, which allows STM not only to infect mammalian hosts but also to enter new infection routes that have been poorly studied so far. With the present dataset, global virulence factors, their impact on infection routes, and potential anti-infective strategies can now be investigated in detail. Especially, we were able to demonstrate functional flagella at 12 °C growth temperature for STM with an altered motility behavior.
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Affiliation(s)
- Laura Elpers
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Jörg Deiwick
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany,CellNanOs – Center of Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany,For correspondence: Michael Hensel
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4
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Crozier L, Marshall J, Holmes A, Wright KM, Rossez Y, Merget B, Humphris S, Toth I, Jackson RW, Holden NJ. The role of l-arabinose metabolism for Escherichia coli O157:H7 in edible plants. MICROBIOLOGY (READING, ENGLAND) 2021; 167:001070. [PMID: 34319868 PMCID: PMC8489885 DOI: 10.1099/mic.0.001070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/11/2021] [Indexed: 12/12/2022]
Abstract
Arabinose is a major plant aldopentose in the form of arabinans complexed in cell wall polysaccharides or glycoproteins (AGP), but comparatively rare as a monosaccharide. l-arabinose is an important bacterial metabolite, accessed by pectolytic micro-organisms such as Pectobacterium atrosepticum via pectin and hemicellulose degrading enzymes. However, not all plant-associated microbes encode cell-wall-degrading enzymes, yet can metabolize l-arabinose, raising questions about their use of and access to the glycan in plants. Therefore, we examined l-arabinose metabolism in the food-borne pathogen Escherichia coli O157:H7 (isolate Sakai) during its colonization of plants. l-arabinose metabolism (araBA) and transport (araF) genes were activated at 18 °C in vitro by l-arabinose and expressed over prolonged periods in planta. Although deletion of araBAD did not impact the colonization ability of E. coli O157:H7 (Sakai) on spinach and lettuce plants (both associated with STEC outbreaks), araA was induced on exposure to spinach cell-wall polysaccharides. Furthermore, debranched and arabinan oligosaccharides induced ara metabolism gene expression in vitro, and stimulated modest proliferation, while immobilized pectin did not. Thus, E. coli O157:H7 (Sakai) can utilize pectin/AGP-derived l-arabinose as a metabolite. Furthermore, it differs fundamentally in ara gene organization, transport and regulation from the related pectinolytic species P. atrosepticum, reflective of distinct plant-associated lifestyles.
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Affiliation(s)
- Louise Crozier
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
| | | | - Ashleigh Holmes
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
| | | | - Yannick Rossez
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
- Université de Technologie de Compiègne, CNRS-FRE 3580, Centre de Recherche de Royallieu, 60203 COMPIEGNE CEDEX, France
| | - Bernhard Merget
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
| | - Sonia Humphris
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
| | - Ian Toth
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
| | - Robert Wilson Jackson
- School of Biological Sciences, The University of Reading, Reading, UK
- Birmingham Institute of Forest Research and School of Biosciences University of Birmingham, Birmingham B15 2TT, UK
| | - Nicola Jean Holden
- The James Hutton Institute, Cell & Molecular Sciences, Dundee, DD2 5DA, UK
- SRUC, Department of Rural Land Use, Aberdeen, AB21 9YA, UK
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5
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Mulaosmanovic E, Windstam ST, Vågsholm I, Alsanius BW. Size Matters: Biological and Food Safety Relevance of Leaf Damage for Colonization of Escherichia coli O157:H7 gfp. Front Microbiol 2021; 11:608086. [PMID: 33584570 PMCID: PMC7873480 DOI: 10.3389/fmicb.2020.608086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/14/2020] [Indexed: 11/13/2022] Open
Abstract
This study examined the biological and food safety relevance of leaf lesions for potential invasion of food pathogens into the plant tissue (internalization). This was done by determining the role of artificial leaf damage in terms of damaged leaf area on proliferation of E. coli O157:H7 gfp+. In a two-factorial experiment, unwashed fresh baby leaf spinach (Spinacia oleracea L.) was subjected to four damage levels (undamaged, low, moderate, high damage; factor 1) and three incubation intervals (0, 1, 2 days post-inoculation; factor 2). Individual leaves were immersed for 15 s in a suspension loaded with E. coli O157:H7 gfp+ (106 CFU × mL–1). The leaves were analyzed individually using image analysis tools to quantify leaf area and number and size of lesions, and using confocal laser scanning and scanning electron microscopy to visualize leaf lesions and presence of the introduced E. coli strain on and within the leaf tissue. Prevalence of E. coli O157:H7 gfp+ was assessed using a culture-dependent technique. The results showed that size of individual lesions and damaged leaf area affected depth of invasion into plant tissue, dispersal to adjacent areas, and number of culturable E. coli O157:H7 gfp+ directly after inoculation. Differences in numbers of the inoculant retrieved from leaf macerate evened out from 2 days post-inoculation, indicating rapid proliferation during the first day post-inoculation. Leaf weight was a crucial factor, as lighter spinach leaves (most likely younger leaves) were more prone to harbor E. coli O157:H7 gfp+, irrespective of damage level. At the high inoculum density used, the risk of consumers’ infection was almost 100%, irrespective of incubation duration or damage level. Even macroscopically intact leaves showed a high risk for infection. These results suggest that the risk to consumers is correlated with how early in the food chain the leaves are contaminated, and the degree of leaf damage. These findings should be taken into account in different steps of leafy green processing. Further attention should be paid to the fate of viable, but non-culturable, shiga-toxigenic E. coli on and in ready-to-eat leafy vegetables.
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Affiliation(s)
- Emina Mulaosmanovic
- Microbial Horticulture Unit, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Sofia T Windstam
- Microbial Horticulture Unit, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Ivar Vågsholm
- Bacteriology and Food Safety Unit, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Beatrix W Alsanius
- Microbial Horticulture Unit, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
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6
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Escherichia coli O157:H7 F9 Fimbriae Recognize Plant Xyloglucan and Elicit a Response in Arabidopsis thaliana. Int J Mol Sci 2020; 21:ijms21249720. [PMID: 33352760 PMCID: PMC7766294 DOI: 10.3390/ijms21249720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/04/2020] [Accepted: 12/14/2020] [Indexed: 11/16/2022] Open
Abstract
Fresh produce is often a source of enterohaemorrhagic Escherichia coli (EHEC) outbreaks. Fimbriae are extracellular structures involved in cell-to-cell attachment and surface colonisation. F9 (Fml) fimbriae have been shown to be expressed at temperatures lower than 37 °C, implying a function beyond the mammalian host. We demonstrate that F9 fimbriae recognize plant cell wall hemicellulose, specifically galactosylated side chains of xyloglucan, using glycan arrays. E. coli expressing F9 fimbriae had a positive advantage for adherence to spinach hemicellulose extract and tissues, which have galactosylated oligosaccharides as recognized by LM24 and LM25 antibodies. As fimbriae are multimeric structures with a molecular pattern, we investigated whether F9 fimbriae could induce a transcriptional response in model plant Arabidopsis thaliana, compared with flagella and another fimbrial type, E. coli common pilus (ECP), using DNA microarrays. F9 induced the differential expression of 435 genes, including genes involved in the plant defence response. The expression of F9 at environmentally relevant temperatures and its recognition of plant xyloglucan adds to the suite of adhesins EHEC has available to exploit the plant niche.
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7
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Wolfson EB, Elvidge J, Tahoun A, Gillespie T, Mantell J, McAteer SP, Rossez Y, Paxton E, Lane F, Shaw DJ, Gill AC, Stevens J, Verkade P, Blocker A, Mahajan A, Gally DL. The interaction of Escherichia coli O157 :H7 and Salmonella Typhimurium flagella with host cell membranes and cytoskeletal components. MICROBIOLOGY (READING, ENGLAND) 2020; 166:947-965. [PMID: 32886602 PMCID: PMC7660914 DOI: 10.1099/mic.0.000959] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/13/2020] [Indexed: 12/11/2022]
Abstract
Bacterial flagella have many established roles beyond swimming motility. Despite clear evidence of flagella-dependent adherence, the specificity of the ligands and mechanisms of binding are still debated. In this study, the molecular basis of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium flagella binding to epithelial cell cultures was investigated. Flagella interactions with host cell surfaces were intimate and crossed cellular boundaries as demarcated by actin and membrane labelling. Scanning electron microscopy revealed flagella disappearing into cellular surfaces and transmission electron microscopy of S. Typhiumurium indicated host membrane deformation and disruption in proximity to flagella. Motor mutants of E. coli O157:H7 and S. Typhimurium caused reduced haemolysis compared to wild-type, indicating that membrane disruption was in part due to flagella rotation. Flagella from E. coli O157 (H7), EPEC O127 (H6) and S. Typhimurium (P1 and P2 flagella) were shown to bind to purified intracellular components of the actin cytoskeleton and directly increase in vitro actin polymerization rates. We propose that flagella interactions with host cell membranes and cytoskeletal components may help prime intimate attachment and invasion for E. coli O157:H7 and S. Typhimurium, respectively.
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Affiliation(s)
- Eliza B. Wolfson
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
- Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Johanna Elvidge
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Amin Tahoun
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
- Faculty of Veterinary Medicine, Kafrelsheikh University, 33516 Kafr el-Sheikh, Egypt
| | - Trudi Gillespie
- IMPACT Facility, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, EH8 9XD, UK
| | - Judith Mantell
- Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Sean P. McAteer
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Yannick Rossez
- Génie Enzymatique et Cellulaire, UMR 7025 CNRS, Centre de recherche Royallieu, Sorbonne Universités, Université de Technologie de Compiègne, Compiègne Cedex, France
| | - Edith Paxton
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Fiona Lane
- Division of Neurobiology, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Darren J. Shaw
- Division of Clinical Sciences, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Andrew C. Gill
- Division of Neurobiology, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Jo Stevens
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Paul Verkade
- Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Ariel Blocker
- Department of Cellular and Molecular Medicine, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK
| | - Arvind Mahajan
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - David L. Gally
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
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8
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Carroll D, Holden N, Gifford ML, Dupuy LX. Framework for Quantification of the Dynamics of Root Colonization by Pseudomonas fluorescens Isolate SBW25. Front Microbiol 2020; 11:585443. [PMID: 33101260 PMCID: PMC7545031 DOI: 10.3389/fmicb.2020.585443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/08/2020] [Indexed: 01/13/2023] Open
Abstract
Colonization of the root surface, or rhizoplane, is one of the first steps for soil-borne bacteria to become established in the plant microbiome. However, the relative contributions of processes, such as bacterial attachment and proliferation is not well characterized, and this limits our ability to comprehend the complex dynamics of microbial communities in the rhizosphere. The work presented here addresses this knowledge gap. A model system was developed to acquire quantitative data on the colonization process of lettuce (Lactuca sativa L. cultivar. All Year Round) roots by Pseudomonas fluorescens isolate SBW25. A theoretical framework is proposed to calculate attachment rate and quantify the relative contribution of bacterial attachment to colonization. This allows the assessment of attachment rates on the root surface beyond the short time period during which it can be quantified experimentally. All techniques proposed are generic and similar analyses could be applied to study various combinations of plants and bacteria, or to assess competition between species. In the future this could allow for selection of microbial traits that improve early colonization and maintenance of targeted isolates in cropping systems, with potential applications for the development of biological fertilizers.
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Affiliation(s)
- Daire Carroll
- Ecological Sciences, The James Hutton Institute, Dundee, United Kingdom.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Nicola Holden
- Northern Faculty, Scotland's Rural College, Aberdeen, United Kingdom
| | - Miriam L Gifford
- School of Life Sciences, University of Warwick, Coventry, United Kingdom.,Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, United Kingdom
| | - Lionel X Dupuy
- Neiker, Department of Conservation of Natural Resources, Derio, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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9
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Cazzola H, Lemaire L, Acket S, Prost E, Duma L, Erhardt M, Čechová P, Trouillas P, Mohareb F, Rossi C, Rossez Y. The Impact of Plasma Membrane Lipid Composition on Flagellum-Mediated Adhesion of Enterohemorrhagic Escherichia coli. mSphere 2020; 5:e00702-20. [PMID: 32938696 PMCID: PMC7494831 DOI: 10.1128/msphere.00702-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 08/27/2020] [Indexed: 01/07/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of foodborne gastrointestinal illness. The adhesion of EHEC to host tissues is the first step enabling bacterial colonization. Adhesins such as fimbriae and flagella mediate this process. Here, we studied the interaction of the bacterial flagellum with the host cell's plasma membrane using giant unilamellar vesicles (GUVs) as a biologically relevant model. Cultured cell lines contain many different molecular components, including proteins and glycoproteins. In contrast, with GUVs, we can characterize the bacterial mode of interaction solely with a defined lipid part of the cell membrane. Bacterial adhesion on GUVs was dependent on the presence of the flagellar filament and its motility. By testing different phospholipid head groups, the nature of the fatty acid chains, or the liposome curvature, we found that lipid packing is a key parameter to enable bacterial adhesion. Using HT-29 cells grown in the presence of polyunsaturated fatty acid (α-linolenic acid) or saturated fatty acid (palmitic acid), we found that α-linolenic acid reduced adhesion of wild-type EHEC but not of a nonflagellated mutant. Finally, our results reveal that the presence of flagella is advantageous for the bacteria to bind to lipid rafts. We speculate that polyunsaturated fatty acids prevent flagellar adhesion on membrane bilayers and play a clear role for optimal host colonization. Flagellum-mediated adhesion to plasma membranes has broad implications for host-pathogen interactions.IMPORTANCE Bacterial adhesion is a crucial step to allow bacteria to colonize their hosts, invade tissues, and form biofilm. Enterohemorrhagic Escherichia coli O157:H7 is a human pathogen and the causative agent of diarrhea and hemorrhagic colitis. Here, we use biomimetic membrane models and cell lines to decipher the impact of lipid content of the plasma membrane on enterohemorrhagic E. coli flagellum-mediated adhesion. Our findings provide evidence that polyunsaturated fatty acid (α-linolenic acid) inhibits E. coli flagellar adhesion to the plasma membrane in a mechanism separate from its antimicrobial and anti-inflammatory functions. In addition, we confirm that cholesterol-enriched lipid microdomains, often called lipid rafts, are important in bacterial adhesion. These findings demonstrate that plasma membrane adhesion via bacterial flagella play a significant role for an important human pathogen. This mechanism represents a promising target for the development of novel antiadhesion therapies.
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Affiliation(s)
- Hélène Cazzola
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
| | - Laurine Lemaire
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
| | - Sébastien Acket
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
| | - Elise Prost
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
| | - Luminita Duma
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
| | - Marc Erhardt
- Institute for Biology-Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Petra Čechová
- RCPTM, Palacký University Olomouc, Olomouc, Czech Republic
| | - Patrick Trouillas
- RCPTM, Palacký University Olomouc, Olomouc, Czech Republic
- INSERM U1248-IPPRITT, University of Limoges, Limoges, France
| | - Fady Mohareb
- The Bioinformatics Group, School of Water, Energy and Environment, Cranfield University, Cranfield, United Kingdom
| | - Claire Rossi
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
| | - Yannick Rossez
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de recherche Royallieu, Compiègne, France
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10
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Holmes A, Pritchard L, Hedley P, Morris J, McAteer SP, Gally DL, Holden NJ. A high-throughput genomic screen identifies a role for the plasmid-borne type II secretion system of Escherichia coli O157:H7 (Sakai) in plant-microbe interactions. Genomics 2020; 112:4242-4253. [PMID: 32663607 DOI: 10.1016/j.ygeno.2020.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/15/2020] [Accepted: 07/09/2020] [Indexed: 01/16/2023]
Abstract
Shiga-toxigenic Escherichia coli (STEC) is often transmitted into food via fresh produce plants, where it can cause disease. To identify early interaction factors for STEC on spinach, a high-throughput positive-selection system was used. A bacterial artificial chromosome (BAC) clone library for isolate Sakai was screened in four successive rounds of short-term (2 h) interaction with spinach roots, and enriched loci identified by microarray. A Bayesian hierarchical model produced 115 CDS credible candidates, comprising seven contiguous genomic regions. Of the two candidate regions selected for functional assessment, the pO157 plasmid-encoded type two secretion system (T2SS) promoted interactions, while a chaperone-usher fimbrial gene cluster (loc6) did not. The T2SS promoted bacterial binding to spinach and appeared to involve the EtpD secretin protein. Furthermore, the T2SS genes, etpD and etpC, were expressed at a plant-relevant temperature of 18 °C, and etpD was expressed in planta by E. coli Sakai on spinach plants.
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Affiliation(s)
- Ashleigh Holmes
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, DD2 5DA, UK
| | - Leighton Pritchard
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, DD2 5DA, UK.; Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK
| | - Peter Hedley
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, DD2 5DA, UK
| | - Jenny Morris
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, DD2 5DA, UK
| | - Sean P McAteer
- The Roslin Institute, Division of Infection and Immunity, University of Edinburgh, R(D)SVS, The Roslin Institute Building, Easter Bush, EH25 9RG, UK
| | - David L Gally
- The Roslin Institute, Division of Infection and Immunity, University of Edinburgh, R(D)SVS, The Roslin Institute Building, Easter Bush, EH25 9RG, UK
| | - Nicola J Holden
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, DD2 5DA, UK.; SRUC, Northern Faculty, Aberdeen, AB21 9YA, UK..
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11
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Methylation of Salmonella Typhimurium flagella promotes bacterial adhesion and host cell invasion. Nat Commun 2020; 11:2013. [PMID: 32332720 PMCID: PMC7181671 DOI: 10.1038/s41467-020-15738-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 03/13/2020] [Indexed: 11/09/2022] Open
Abstract
The long external filament of bacterial flagella is composed of several thousand copies of a single protein, flagellin. Here, we explore the role played by lysine methylation of flagellin in Salmonella, which requires the methylase FliB. We show that both flagellins of Salmonella enterica serovar Typhimurium, FliC and FljB, are methylated at surface-exposed lysine residues by FliB. A Salmonella Typhimurium mutant deficient in flagellin methylation is outcompeted for gut colonization in a gastroenteritis mouse model, and methylation of flagellin promotes bacterial invasion of epithelial cells in vitro. Lysine methylation increases the surface hydrophobicity of flagellin, and enhances flagella-dependent adhesion of Salmonella to phosphatidylcholine vesicles and epithelial cells. Therefore, posttranslational methylation of flagellin facilitates adhesion of Salmonella Typhimurium to hydrophobic host cell surfaces, and contributes to efficient gut colonization and host infection. Flagellin proteins of Salmonella flagella are methylated. Here, the authors show that flagellin methylation facilitates adhesion of Salmonella to hydrophobic host-cell surfaces, and contributes to efficient gut colonization and host infection.
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12
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Factors Required for Adhesion of Salmonella enterica Serovar Typhimurium to Corn Salad (Valerianella locusta). Appl Environ Microbiol 2020; 86:AEM.02757-19. [PMID: 32033951 DOI: 10.1128/aem.02757-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/04/2020] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica is a foodborne pathogen often leading to gastroenteritis and is commonly acquired by consumption of contaminated food of animal origin. However, frequency of outbreaks linked to the consumption of fresh or minimally processed food of nonanimal origin is increasing. New infection routes of S. enterica by vegetables, fruits, nuts, and herbs have to be considered. This leads to special interest in S. enterica interactions with leafy products, e.g., salads, that are mainly consumed in a minimally processed form. The attachment of S. enterica to salad is a crucial step in contamination, but little is known about the bacterial factors required and mechanisms of adhesion. S. enterica possesses a complex set of adhesive structures whose functions are only partly understood. Potentially, S. enterica may deploy multiple adhesive strategies for adhering to various salad species and other vegetables. In this study, we systematically analyzed the contributions of the complete adhesiome, of lipopolysaccharide (LPS), and of flagellum-mediated motility of S. enterica serovar Typhimurium (STM) in adhesion to Valerianella locusta (corn salad). We deployed a reductionist, synthetic approach to identify factors involved in the surface binding of STM to leaves of corn salad, with particular regard to the expression of all known adhesive structures, using the Tet-on system. This work reveals the contribution of Saf fimbriae, type 1 secretion system-secreted BapA, an intact LPS, and flagellum-mediated motility of STM in adhesion to corn salad leaves.IMPORTANCE Transmission of gastrointestinal pathogens by contaminated fresh produce is of increasing relevance to human health. However, the mechanisms of contamination of, persistence on, and transmission by fresh produce are poorly understood. We investigated the contributions of the various adhesive structures of STM to the initial event in transmission, i.e., binding to the plant surface. A reductionist system was used that allowed experimentally controlled surface expression of individual adhesive structures and analyses of the contribution to binding to leave surfaces of corn salad under laboratory conditions. The model system allowed the determination of the relative contributions of fimbrial and nonfimbrial adhesins, the type 3 secretion systems, the O antigen of lipopolysaccharide, the flagella, and chemotaxis of STM to binding to corn salad leaves. Based on these data, future work could reveal the mechanism of binding and the relevance of interaction under agricultural conditions.
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13
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Oblessuc PR, Matiolli CC, Melotto M. Novel molecular components involved in callose-mediated Arabidopsis defense against Salmonella enterica and Escherichia coli O157:H7. BMC PLANT BIOLOGY 2020; 20:16. [PMID: 31914927 PMCID: PMC6950905 DOI: 10.1186/s12870-019-2232-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/30/2019] [Indexed: 05/26/2023]
Abstract
BACKGROUND Food contamination with Salmonella enterica and enterohemorrhagic Escherichia coli is among the leading causes of foodborne illnesses worldwide and crop plants are associated with > 50% of the disease outbreaks. However, the mechanisms underlying the interaction of these human pathogens with plants remain elusive. In this study, we have explored plant resistance mechanisms against these enterobacteria and the plant pathogen Pseudomonas syringae pv. tomato (Pst) DC3118, as an opportunity to improve food safety. RESULTS We found that S. enterica serovar Typhimurium (STm) transcriptionally modulates stress responses in Arabidopsis leaves, including induction of two hallmark processes of plant defense: ROS burst and cell wall modifications. Analyses of plants with a mutation in the potentially STm-induced gene EXO70H4 revealed that its encoded protein is required for stomatal defense against STm and E. coli O157:H7, but not against Pst DC3118. In the apoplast however, EXO70H4 is required for defense against STm and Pst DC3118, but not against E. coli O157:H7. Moreover, EXO70H4 is required for callose deposition, but had no function in ROS burst, triggered by all three bacteria. The salicylic acid (SA) signaling and biosynthesis proteins NPR1 and ICS1, respectively, were involved in stomatal and apoplastic defense, as well as callose deposition, against human and plant pathogens. CONCLUSIONS The results show that EXO70H4 is involved in stomatal and apoplastic defenses in Arabidopsis and suggest that EXO70H4-mediated defense play a distinct role in guard cells and leaf mesophyll cells in a bacteria-dependent manner. Nonetheless, EXO70H4 contributes to callose deposition in response to both human and plant pathogens. NPR1 and ICS1, two proteins involved in the SA signaling pathway, are important to inhibit leaf internalization and apoplastic persistence of enterobacteria and proliferation of phytopathogens. These findings highlight the existence of unique and shared plant genetic components to fight off diverse bacterial pathogens providing specific targets for the prevention of foodborne diseases.
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Affiliation(s)
- Paula Rodrigues Oblessuc
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | | | - Maeli Melotto
- Department of Plant Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA.
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14
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Merget B, Forbes KJ, Brennan F, McAteer S, Shepherd T, Strachan NJC, Holden NJ. Influence of Plant Species, Tissue Type, and Temperature on the Capacity of Shiga-Toxigenic Escherichia coli To Colonize, Grow, and Be Internalized by Plants. Appl Environ Microbiol 2019; 85:e00123-19. [PMID: 30902860 PMCID: PMC6532046 DOI: 10.1128/aem.00123-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/20/2019] [Indexed: 12/21/2022] Open
Abstract
Contamination of fresh produce with pathogenic Escherichia coli, including Shiga-toxigenic E. coli (STEC), represents a serious risk to human health. Colonization is governed by multiple bacterial and plant factors that can impact the probability and suitability of bacterial growth. Thus, we aimed to determine whether the growth potential of STEC for plants associated with foodborne outbreaks (two leafy vegetables and two sprouted seed species) is predictive of the colonization of living plants, as assessed from growth kinetics and biofilm formation in plant extracts. The fitness of STEC isolates was compared to that of environmental E. coli isolates at temperatures relevant to plant growth. Growth kinetics in plant extracts varied in a plant-dependent and isolate-dependent manner for all isolates, with spinach leaf lysates supporting the highest rates of growth. Spinach extracts also supported the highest levels of biofilm formation. Saccharides were identified to be the major driver of bacterial growth, although no single metabolite could be correlated with growth kinetics. The highest level of in planta colonization occurred on alfalfa sprouts, though internalization was 10 times more prevalent in the leafy vegetables than in sprouted seeds. Marked differences in in planta growth meant that the growth potential of STEC could be inferred only for sprouted seeds. In contrast, biofilm formation in extracts related to spinach colonization. Overall, the capacity of E. coli to colonize, grow, and be internalized within plants or plant-derived matrices was influenced by the isolate type, plant species, plant tissue type, and temperature, complicating any straightforward relationship between in vitro and in planta behaviors.IMPORTANCE Fresh produce is an important vehicle for STEC transmission, and experimental evidence shows that STEC can colonize plants as secondary hosts, but differences in the capacity to colonize occur between different plant species and tissues. Therefore, an understanding of the impact that these plant factors have on the ability of STEC to grow and establish is required for food safety considerations and risk assessment. Here, we determined whether growth and the ability of STEC to form biofilms in plant extracts could be related to specific plant metabolites or could predict the ability of the bacteria to colonize living plants. Growth rates for sprouted seeds (alfalfa and fenugreek) but not those for leafy vegetables (lettuce and spinach) exhibited a positive relationship between plant extracts and living plants. Therefore, the detailed variations at the level of the bacterial isolate, plant species, and tissue type all need to be considered in risk assessment.
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Affiliation(s)
- Bernhard Merget
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
- School of Biological Sciences, The University of Aberdeen, Aberdeen, United Kingdom
| | - Ken J Forbes
- School of Medicine and Dentistry, The University of Aberdeen, Aberdeen, United Kingdom
| | - Fiona Brennan
- Teagasc, Department of Environment, Soils and Land-Use, Wexford, Republic of Ireland
| | - Sean McAteer
- Roslin Institute & R(D)SVS, The University of Edinburgh, Edinburgh, United Kingdom
| | - Tom Shepherd
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
| | - Norval J C Strachan
- School of Biological Sciences, The University of Aberdeen, Aberdeen, United Kingdom
| | - Nicola J Holden
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
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15
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Response to Questions Posed by the Food and Drug Administration Regarding Virulence Factors and Attributes that Define Foodborne Shiga Toxin-Producing Escherichia coli (STEC) as Severe Human Pathogens †. J Food Prot 2019; 82:724-767. [PMID: 30969806 DOI: 10.4315/0362-028x.jfp-18-479] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
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- NACMCF Executive Secretariat, * U.S. Department of Agriculture, Food Safety and Inspection Service, Office of Public Health Science, PP3, 9-178, 1400 Independence Avenue S.W., Washington, D.C. 20250-3700, USA
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16
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Hutchison ML, Harrison D, Heath JF, Monaghan JM. Fate of Escherichia coli O145 present naturally in bovine slurry applied to vegetables before harvest, after washing and simulated wholesale and retail distribution. J Appl Microbiol 2017; 123:1597-1606. [PMID: 28948664 DOI: 10.1111/jam.13593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/08/2017] [Accepted: 09/20/2017] [Indexed: 11/30/2022]
Abstract
AIMS To determine the fate of Escherichia coli on vegetables that were processed through commercial wash treatments and stored under simulated retail conditions at 4°C or wholesale at fluctuating ambient temperatures (0-25°C, dependent on season). METHODS AND RESULTS Bovine slurry that was naturally contaminated with E. coli O145 was applied without dilution or diluted 1:10 using borehole water to growing potatoes, leeks or carrots. Manure was applied 1 week prior to harvest to simulate a near-harvest contamination event by manure deposition or an application of contaminated water to simulate a flooding event or irrigation from a contaminated water source. At harvest, crops were contaminated at up to 2 log cfu g-1 . Washing transferred E. coli into the water of a flotation tank used for potato washing and did not completely remove all traces of contamination from the crop. Manure-contaminated potatoes were observed to contain 0·72 cfu E. coli O145 g-1 after processing and retail storage. Manure-contaminated leeks harboured 0·73-1·55 cfu E. coli O145 g-1 after washing and storage. There was no cross-contamination when leeks were spray washed. Washing in an abrasive drum resulted in less than perfect decontamination for manure-contaminated carrots. There were five post-distribution isolations from carrots irrigated with contaminated water 24 h prior to harvest. CONCLUSIONS Standard commercial washing and distribution conditions may be insufficient to reliably control human pathogenic E. coli on fresh produce. SIGNIFICANCE AND IMPACT Previous speculation that the cause of a UK foodborne disease outbreak was soil from imperfectly cleaned vegetables is plausible.
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Affiliation(s)
- M L Hutchison
- Hutchison Scientific Ltd, Dundee, UK.,School of Veterinary Sciences, Food Microbiology, University of Bristol, Langford, UK
| | - D Harrison
- School of Veterinary Sciences, Food Microbiology, University of Bristol, Langford, UK
| | - J F Heath
- Department of Crop and Environment Science, Fresh Produce Research Centre, Harper Adams University, Newport, Shropshire, UK
| | - J M Monaghan
- Department of Crop and Environment Science, Fresh Produce Research Centre, Harper Adams University, Newport, Shropshire, UK
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17
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Snopková K, Sedlář K, Bosák J, Chaloupková E, Sedláček I, Provazník I, Šmajs D. Free-Living Enterobacterium Pragia fontium 24613: Complete Genome Sequence and Metabolic Profiling. Evol Bioinform Online 2017; 13:1176934317700863. [PMID: 28469381 PMCID: PMC5395255 DOI: 10.1177/1176934317700863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 02/12/2017] [Indexed: 11/23/2022] Open
Abstract
Pragia fontium is one of the few species that belongs to the group of atypical hydrogen sulfide-producing enterobacteria. Unlike other members of this closely related group, P. fontium is not associated with any known host and has been reported as a free-living bacterium. Whole genome sequencing and metabolic fingerprinting confirmed the phylogenetic position of P. fontium inside the group of atypical H2S producers. Genomic data have revealed that P. fontium 24613 has limited pathogenic potential, although there are signs of genome decay. Although the lack of specific virulence factors and no association with a host species suggest a free-living style, the signs of genome decay suggest a process of adaptation to an as-yet-unknown host.
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Affiliation(s)
| | - Karel Sedlář
- Department of Biomedical Engineering, Brno University of Technology, Brno, Czech Republic
| | - Juraj Bosák
- Department of Biology, Masaryk University, Brno, Czech Republic
| | - Eva Chaloupková
- Department of Biology, Masaryk University, Brno, Czech Republic
| | - Ivo Sedláček
- Czech Collection of Microorganisms, Department of Experimental Biology, Masaryk University, Brno, Czech Republic
| | - Ivo Provazník
- Department of Biomedical Engineering, Brno University of Technology, Brno, Czech Republic
| | - David Šmajs
- Department of Biology, Masaryk University, Brno, Czech Republic
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18
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Bose T, Venkatesh KV, Mande SS. Computational Analysis of Host-Pathogen Protein Interactions between Humans and Different Strains of Enterohemorrhagic Escherichia coli. Front Cell Infect Microbiol 2017; 7:128. [PMID: 28469995 PMCID: PMC5395655 DOI: 10.3389/fcimb.2017.00128] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/28/2017] [Indexed: 01/18/2023] Open
Abstract
Serotype O157:H7, an enterohemorrhagic Escherichia coli (EHEC), is known to cause gastrointestinal and systemic illnesses ranging from diarrhea and hemorrhagic colitis to potentially fatal hemolytic uremic syndrome. Specific genetic factors like ompA, nsrR, and LEE genes are known to play roles in EHEC pathogenesis. However, these factors are not specific to EHEC and their presence in several non-pathogenic strains indicates that additional factors are involved in pathogenicity. We propose a comprehensive effort to screen for such potential genetic elements, through investigation of biomolecular interactions between E. coli and their host. In this work, an in silico investigation of the protein–protein interactions (PPIs) between human cells and four EHEC strains (viz., EDL933, Sakai, EC4115, and TW14359) was performed in order to understand the virulence and host-colonization strategies of these strains. Potential host–pathogen interactions (HPIs) between human cells and the “non-pathogenic” E. coli strain MG1655 were also probed to evaluate whether and how the variations in the genomes could translate into altered virulence and host-colonization capabilities of the studied bacterial strains. Results indicate that a small subset of HPIs are unique to the studied pathogens and can be implicated in virulence. This subset of interactions involved E. coli proteins like YhdW, ChuT, EivG, and HlyA. These proteins have previously been reported to be involved in bacterial virulence. In addition, clear differences in lineage and clade-specific HPI profiles could be identified. Furthermore, available gene expression profiles of the HPI-proteins were utilized to estimate the proportion of proteins which may be involved in interactions. We hypothesized that a cumulative score of the ratios of bound:unbound proteins (involved in HPIs) would indicate the extent of colonization. Thus, we designed the Host Colonization Index (HCI) measure to determine the host colonization potential of the E. coli strains. Pathogenic strains of E. coli were observed to have higher HCIs as compared to a non-pathogenic laboratory strain. However, no significant differences among the HCIs of the two pathogenic groups were observed. Overall, our findings are expected to provide additional insights into EHEC pathogenesis and are likely to aid in designing alternate preventive and therapeutic strategies.
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Affiliation(s)
- Tungadri Bose
- Bio-Sciences R&D Division, TCS Innovation Labs, Tata Consultancy Services LimitedPune, India.,Department of Chemical Engineering, Indian Institute of Technology BombayMumbai, India
| | - K V Venkatesh
- Department of Chemical Engineering, Indian Institute of Technology BombayMumbai, India
| | - Sharmila S Mande
- Bio-Sciences R&D Division, TCS Innovation Labs, Tata Consultancy Services LimitedPune, India
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19
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Marshall J, Rossez Y, Mainda G, Gally DL, Daniell TJ, Holden NJ. Alternate thermoregulation and functional binding ofEscherichia colitype 1 fimbriae in environmental and animal isolates. FEMS Microbiol Lett 2016; 363:fnw251. [DOI: 10.1093/femsle/fnw251] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/24/2016] [Accepted: 11/02/2016] [Indexed: 11/14/2022] Open
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20
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Kinsinger NM, Mayton HM, Luth MR, Walker SL. Efficacy of post-harvest rinsing and bleach disinfection of E. coli O157:H7 on spinach leaf surfaces. Food Microbiol 2016; 62:212-220. [PMID: 27889151 DOI: 10.1016/j.fm.2016.10.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 10/03/2016] [Accepted: 10/08/2016] [Indexed: 11/17/2022]
Abstract
Attachment and detachment kinetics of Escherichia coli O157:H7 from baby spinach leaf epicuticle layers were investigated using a parallel plate flow chamber. Mass transfer rate coefficients were used to determine the impact of water chemistry and common bleach disinfection rinses on the removal and inactivation of the pathogen. Attachment mass transfer rate coefficients generally increased with ionic strength. Detachment mass transfer rate coefficients were nearly the same in KCl and AGW rinses; however, the detachment phase lasted longer in KCl than AGW (18 ± 4 min and 4 ± 2 min, respectively), indicating that the ions present during attachment play a significant role in the cells' ability to remain attached. Specifically, increasing bleach rinse concentration by two orders of magnitude was found to increase the detachment mass transfer rate coefficient by 20 times (from 5.7 ± 0.7 × 10-11 m/s to 112.1 ± 26.8 × 10-11 m/s for 10 ppb and 1000 ppb, respectively), and up to 88 ± 4% of attached cells remained alive. The spinach leaf texture was incorporated within a COMSOL model of disinfectant concentration gradients, which revealed nearly 15% of the leaf surface is exposed to almost 1000 times lower concentration than the bulk rinse solution.
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Affiliation(s)
- Nichola M Kinsinger
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, United States
| | - Holly M Mayton
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, United States
| | - Madeline R Luth
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, United States
| | - Sharon L Walker
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, United States.
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21
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Golubov A, Byeon B, Woycicki R, Laing C, Gannon V, Kovalchuk I. Transcriptomic profiling of Arabidopsis thaliana plants exposed to the human pathogen Escherichia coli O157-H7. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2016. [DOI: 10.1016/j.bcab.2016.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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22
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Crozier L, Hedley PE, Morris J, Wagstaff C, Andrews SC, Toth I, Jackson RW, Holden NJ. Whole-Transcriptome Analysis of Verocytotoxigenic Escherichia coli O157:H7 (Sakai) Suggests Plant-Species-Specific Metabolic Responses on Exposure to Spinach and Lettuce Extracts. Front Microbiol 2016; 7:1088. [PMID: 27462311 PMCID: PMC4940412 DOI: 10.3389/fmicb.2016.01088] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 06/29/2016] [Indexed: 12/11/2022] Open
Abstract
Verocytotoxigenic Escherichia coli (VTEC) can contaminate crop plants, potentially using them as secondary hosts, which can lead to food-borne infection. Currently, little is known about the influence of the specific plant species on the success of bacterial colonization. As such, we compared the ability of the VTEC strain, E. coli O157:H7 'Sakai,' to colonize the roots and leaves of four leafy vegetables: spinach (Spinacia oleracea), lettuce (Lactuca sativa), vining green pea (Pisum sativum), and prickly lettuce (Lactuca serriola), a wild relative of domesticated lettuce. Also, to determine the drivers of the initial response on interaction with plant tissue, the whole transcriptome of E. coli O157:H7 Sakai was analyzed following exposure to plant extracts of varying complexity (spinach leaf lysates or root exudates, and leaf cell wall polysaccharides from spinach or lettuce). Plant extracts were used to reduce heterogeneity inherent in plant-microbe interactions and remove the effect of plant immunity. This dual approach provided information on the initial adaptive response of E. coli O157:H7 Sakai to the plant environment together with the influence of the living plant during bacterial establishment and colonization. Results showed that both the plant tissue type and the plant species strongly influence the short-term (1 h) transcriptional response to extracts as well as longer-term (10 days) plant colonization or persistence. We show that propagation temperature (37 vs. 18°C) has a major impact on the expression profile and therefore pre-adaptation of bacteria to a plant-relevant temperature is necessary to avoid misleading temperature-dependent wholescale gene-expression changes in response to plant material. For each of the plant extracts tested, the largest group of (annotated) differentially regulated genes were associated with metabolism. However, large-scale differences in the metabolic and biosynthetic pathways between treatment types indicate specificity in substrate utilization. Induction of stress-response genes reflected the apparent physiological status of the bacterial genes in each extract, as a result of glutamate-dependent acid resistance, nutrient stress, or translational stalling. A large proportion of differentially regulated genes are uncharacterized (annotated as hypothetical), which could indicate yet to be described functional roles associated with plant interaction for E. coli O157:H7 Sakai.
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Affiliation(s)
- Louise Crozier
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Pete E. Hedley
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Jenny Morris
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | - Carol Wagstaff
- School of Chemistry, Food and Pharmacy, The University of ReadingReading, UK
| | - Simon C. Andrews
- School of Biological Sciences, The University of ReadingReading, UK
| | - Ian Toth
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
| | | | - Nicola J. Holden
- Cell and Molecular Sciences, The James Hutton InstituteDundee, UK
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23
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More than a locomotive organelle: flagella in Escherichia coli. Appl Microbiol Biotechnol 2015; 99:8883-90. [DOI: 10.1007/s00253-015-6946-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/17/2015] [Accepted: 08/20/2015] [Indexed: 10/23/2022]
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24
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Yuan Y, Gao M. Genomic analysis of a ginger pathogen Bacillus pumilus providing the understanding to the pathogenesis and the novel control strategy. Sci Rep 2015; 5:10259. [PMID: 25989507 PMCID: PMC4437294 DOI: 10.1038/srep10259] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 04/07/2015] [Indexed: 02/06/2023] Open
Abstract
Bacillus pumilus has been widely identified as a pathogen of plant and human, while the genetic information is rarely available for pathogenic B. pumilus strains. B. pumilus GR8 is a pathogen that causes ginger rhizome rot disease by invading ginger rhizome parenchymatous tissues, growing in the extracellular space, and producing plant cell wall-degrading enzymes to destroy ginger cells. In this study, the genome of GR8 was sequenced and characterized. This genome was the third completely sequenced genome of the B. pumilus species, and it exhibited high similarity to the genome of the B. pumilus strain B6033. The genome of GR8 was 3.67 Mb in length and encoded 3,713 putative ORFs. Among these predicted proteins, numerous plant cell wall-degrading enzymes and several proteins associated with invading and adapting to the environment in the extracellular space of the ginger rhizome parenchymatous tissue were found. The GR8 genome contained only one restriction-modification system and no CRISPR/Cas system. The lack of phage-resistant system suggested that phages might be potential agents for the control of GR8. The genomic analysis of GR8 provided the understanding to the pathogenesis and the phage-control strategy of pathogenic B. pumilus strains.
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Affiliation(s)
- Yihui Yuan
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China
| | - Meiying Gao
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, P.R. China
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25
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Rossez Y, Wolfson EB, Holmes A, Gally DL, Holden NJ. Bacterial flagella: twist and stick, or dodge across the kingdoms. PLoS Pathog 2015; 11:e1004483. [PMID: 25590430 PMCID: PMC4295861 DOI: 10.1371/journal.ppat.1004483] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The flagellum organelle is an intricate multiprotein assembly best known for its rotational propulsion of bacteria. However, recent studies have expanded our knowledge of other functions in pathogenic contexts, particularly adherence and immune modulation, e.g., for Salmonella enterica, Campylobacter jejuni, Pseudomonas aeruginosa, and Escherichia coli. Flagella-mediated adherence is important in host colonisation for several plant and animal pathogens, but the specific interactions that promote flagella binding to such diverse host tissues has remained elusive. Recent work has shown that the organelles act like probes that find favourable surface topologies to initiate binding. An emerging theme is that more general properties, such as ionic charge of repetitive binding epitopes and rotational force, allow interactions with plasma membrane components. At the same time, flagellin monomers are important inducers of plant and animal innate immunity: variation in their recognition impacts the course and outcome of infections in hosts from both kingdoms. Bacteria have evolved different strategies to evade or even promote this specific recognition, with some important differences shown for phytopathogens. These studies have provided a wider appreciation of the functions of bacterial flagella in the context of both plant and animal reservoirs.
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Affiliation(s)
- Yannick Rossez
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, United Kingdom
| | - Eliza B. Wolfson
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, United Kingdom
| | - Ashleigh Holmes
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, United Kingdom
| | - David L. Gally
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, United Kingdom
| | - Nicola J. Holden
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, United Kingdom
- * E-mail:
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Rossez Y, Holmes A, Lodberg-Pedersen H, Birse L, Marshall J, Willats WGT, Toth IK, Holden NJ. Escherichia coli common pilus (ECP) targets arabinosyl residues in plant cell walls to mediate adhesion to fresh produce plants. J Biol Chem 2014; 289:34349-65. [PMID: 25320086 DOI: 10.1074/jbc.m114.587717] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Outbreaks of verotoxigenic Escherichia coli are often associated with fresh produce. However, the molecular basis to adherence is unknown beyond ionic lipid-flagellum interactions in plant cell membranes. We demonstrate that arabinans present in different constituents of plant cell walls are targeted for adherence by E. coli common pilus (ECP; or meningitis-associated and temperature-regulated (Mat) fimbriae) for E. coli serotypes O157:H7 and O18:K1:H7. l-Arabinose is a common constituent of plant cell wall that is rarely found in other organisms, whereas ECP is widespread in E. coli and other environmental enteric species. ECP bound to oligosaccharides of at least arabinotriose or longer in a glycan array, plant cell wall pectic polysaccharides, and plant glycoproteins. Recognition overlapped with the antibody LM13, which binds arabinanase-sensitive pectic epitopes, and showed a preferential affinity for (1→5)-α-linked l-arabinosyl residues and longer chains of arabinan as demonstrated with the use of arabinan-degrading enzymes. Functional adherence in planta was mediated by the adhesin EcpD in combination with the structural subunit, EcpA, and expression was demonstrated with an ecpR-GFP fusion and ECP antibodies. Spinach was found to be enriched for ECP/LM13 targets compared with lettuce. Specific recognition of arabinosyl residues may help explain the persistence of E. coli in the wider environment and association of verotoxigenic E. coli with some fresh produce plants by exploitation of a glycan found only in plant, not animal, cells.
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Affiliation(s)
- Yannick Rossez
- From the Cellular and Molecular Sciences, James Hutton Institute, Dundee DD2 5DA, Scotland, United Kingdom and
| | - Ashleigh Holmes
- From the Cellular and Molecular Sciences, James Hutton Institute, Dundee DD2 5DA, Scotland, United Kingdom and
| | - Henriette Lodberg-Pedersen
- Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg Copenhagen, Denmark
| | - Louise Birse
- From the Cellular and Molecular Sciences, James Hutton Institute, Dundee DD2 5DA, Scotland, United Kingdom and
| | - Jacqueline Marshall
- From the Cellular and Molecular Sciences, James Hutton Institute, Dundee DD2 5DA, Scotland, United Kingdom and
| | - William G T Willats
- Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg Copenhagen, Denmark
| | - Ian K Toth
- From the Cellular and Molecular Sciences, James Hutton Institute, Dundee DD2 5DA, Scotland, United Kingdom and
| | - Nicola J Holden
- From the Cellular and Molecular Sciences, James Hutton Institute, Dundee DD2 5DA, Scotland, United Kingdom and
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Holmes A, Birse L, Jackson RW, Holden NJ. An optimized method for the extraction of bacterial mRNA from plant roots infected with Escherichia coli O157:H7. Front Microbiol 2014; 5:286. [PMID: 25018749 PMCID: PMC4071639 DOI: 10.3389/fmicb.2014.00286] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/23/2014] [Indexed: 01/08/2023] Open
Abstract
Analysis of microbial gene expression during host colonization provides valuable information on the nature of interaction, beneficial or pathogenic, and the adaptive processes involved. Isolation of bacterial mRNA for in planta analysis can be challenging where host nucleic acid may dominate the preparation, or inhibitory compounds affect downstream analysis, e.g., quantitative reverse transcriptase PCR (qPCR), microarray, or RNA-seq. The goal of this work was to optimize the isolation of bacterial mRNA of food-borne pathogens from living plants. Reported methods for recovery of phytopathogen-infected plant material, using hot phenol extraction and high concentration of bacterial inoculation or large amounts of infected tissues, were found to be inappropriate for plant roots inoculated with Escherichia coli O157:H7. The bacterial RNA yields were too low and increased plant material resulted in a dominance of plant RNA in the sample. To improve the yield of bacterial RNA and reduce the number of plants required, an optimized method was developed which combines bead beating with directed bacterial lysis using SDS and lysozyme. Inhibitory plant compounds, such as phenolics and polysaccharides, were counteracted with the addition of high-molecular-weight polyethylene glycol and hexadecyltrimethyl ammonium bromide. The new method increased the total yield of bacterial mRNA substantially and allowed assessment of gene expression by qPCR. This method can be applied to other bacterial species associated with plant roots, and also in the wider context of food safety.
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Affiliation(s)
- Ashleigh Holmes
- Cell and Molecular Sciences, The James Hutton Institute Invergowrie, Dundee, UK
| | - Louise Birse
- Cell and Molecular Sciences, The James Hutton Institute Invergowrie, Dundee, UK
| | - Robert W Jackson
- School of Biological Sciences, The University of Reading Knight Building, Whiteknights, Reading, UK
| | - Nicola J Holden
- Cell and Molecular Sciences, The James Hutton Institute Invergowrie, Dundee, UK
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