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Fratty IS, Shachar D, Katsman M, Yaron S. The activity of BcsZ of Salmonella Typhimurium and its role in Salmonella-plants interactions. Front Cell Infect Microbiol 2022; 12:967796. [PMID: 36081768 PMCID: PMC9445439 DOI: 10.3389/fcimb.2022.967796] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/25/2022] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica is one of the most common human pathogens associated with fresh produce outbreaks. The present study suggests that expression of BcsZ, one of the proteins in the bcs complex, enhances the survival of Salmonella Typhimurium on parsley. BcsZ demonstrated glucanase activity with the substrates carboxymethylcellulose and crystalline cellulose, and was responsible for a major part of the S. Typhimurium CMCase activity. Moreover, there was constitutive expression of BcsZ, which was also manifested after exposure to plant polysaccharides and parsley-leaf extract. In an in-planta model, overexpression of BcsZ significantly improved the epiphytic and endophytic survival of S. Typhimurium on/in parsley leaves compared with the wild-type strain and bcsZ null mutant. Interestingly, necrotic lesions appeared on the parsley leaf after infiltration of Salmonella overexpressing BcsZ, while infiltration of the wild-type S. Typhimurium did not cause any visible symptoms. Infiltration of purified BcsZ enzyme, or its degradation products also caused symptoms on parsley leaves. We suggest that the BcsZ degradation products trigger the plant’s defense response, causing local necrotic symptoms. These results indicate that BcsZ plays an important role in the Salmonella-plant interactions, and imply that injured bacteria may take part in these interactions.
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Truong H, Garmyn D, Gal L, Fournier C, Sevellec Y, Jeandroz S, Piveteau P. Plants as a realized niche for Listeria monocytogenes. Microbiologyopen 2021; 10:e1255. [PMID: 34964288 PMCID: PMC8710918 DOI: 10.1002/mbo3.1255] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/09/2021] [Accepted: 11/18/2021] [Indexed: 12/27/2022] Open
Abstract
Listeria monocytogenes is a human pathogen. It is the causative agent of listeriosis, the leading cause of bacterial-linked foodborne mortality in Europe and elsewhere. Outbreaks of listeriosis have been associated with the consumption of fresh produce including vegetables and fruits. In this review we summarize current data providing direct or indirect evidence that plants can serve as habitat for L. monocytogenes, enabling this human pathogen to survive and grow. The current knowledge of the mechanisms involved in the interaction of this bacterium with plants is addressed, and whether this foodborne pathogen elicits an immune response in plants is discussed.
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Affiliation(s)
- Hoai‐Nam Truong
- Agroécologie, AgroSup Dijon, CNRS, INRAEUniversity Bourgogne Franche‐ComtéDijonFrance
| | - Dominique Garmyn
- Agroécologie, AgroSup Dijon, CNRS, INRAEUniversity Bourgogne Franche‐ComtéDijonFrance
| | - Laurent Gal
- Agroécologie, AgroSup Dijon, CNRS, INRAEUniversity Bourgogne Franche‐ComtéDijonFrance
| | - Carine Fournier
- Agroécologie, AgroSup Dijon, CNRS, INRAEUniversity Bourgogne Franche‐ComtéDijonFrance
| | - Yann Sevellec
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Laboratory for Food Safety, Salmonella and Listeria UnitParis‐Est UniversityMaisons‐AlfortCedexFrance
| | - Sylvain Jeandroz
- Agroécologie, AgroSup Dijon, CNRS, INRAEUniversity Bourgogne Franche‐ComtéDijonFrance
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Vital PG, Caballes MBD, Rivera WL. Antimicrobial resistance in Escherichia coli and Salmonella spp. isolates from fresh produce and the impact to food safety. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2017; 52:683-689. [PMID: 28679083 DOI: 10.1080/03601234.2017.1331676] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Foodborne diseases associated with fresh produce consumption have escalated worldwide, causing microbial safety of produce of critical importance. Bacteria that have increasingly been detected in fresh produce are Escherichia coli and Salmonella spp., both of which have been shown to progressively display antimicrobial resistance. The study focused on the assessment of antimicrobial resistance of these enteric bacteria from different kinds of fresh produce from various open air markets and supermarkets in the Philippines. Using the disk diffusion assay on a total of 50 bacterial isolates obtained from 410 fresh produce surveyed, monoresistance to tetracycline was observed to be the most prevalent (38%), followed by multidrug resistance to tetracycline, chloramphenicol, ciprofloxacin, and nalidixic acid (4%), and lastly by dual resistance to tetracycline and chloramphenicol (2%). Using multiplex and simplex polymerase chain reaction (PCR) assays, tetA (75%) and tetB (9%) were found in tetracycline resistant isolates, whereas catI (67%) and catIII (33%) were detected in chloramphenicol resistant isolates. Sequence analysis of gyr and par genes from the ciprofloxacin and nalidixic acid resistant isolates revealed different mutations. Based on the results, fresh produce act as a reservoir of these antibiotic resistant bacteria which may pose health threat to consumers.
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Affiliation(s)
- Pierangeli G Vital
- a Institute of Biology, College of Science, University of the Philippines Diliman , Quezon City , Philippines
- b Natural Sciences Research Institute, University of the Philippines Diliman , Quezon City , Philippines
| | - Marie Bernadine D Caballes
- a Institute of Biology, College of Science, University of the Philippines Diliman , Quezon City , Philippines
| | - Windell L Rivera
- a Institute of Biology, College of Science, University of the Philippines Diliman , Quezon City , Philippines
- b Natural Sciences Research Institute, University of the Philippines Diliman , Quezon City , Philippines
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Feng K, Hu W, Jiang A, Saren G, Xu Y, Ji Y, Shao W. Growth ofSalmonellaspp. andEscherichia coliO157:H7 on Fresh-Cut Fruits Stored at Different Temperatures. Foodborne Pathog Dis 2017; 14:510-517. [DOI: 10.1089/fpd.2016.2255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Ke Feng
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
- College of Life Science, Dalian Nationalities University, Dalian, China
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian, China
| | - Wenzhong Hu
- College of Life Science, Dalian Nationalities University, Dalian, China
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian, China
| | - Aili Jiang
- College of Life Science, Dalian Nationalities University, Dalian, China
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian, China
| | - Gaowa Saren
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
- College of Life Science, Dalian Nationalities University, Dalian, China
- Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian, China
| | - Yongping Xu
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
| | - Yaru Ji
- School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China
- College of Life Science, Dalian Nationalities University, Dalian, China
| | - Wenjun Shao
- College of Life Science, Dalian Nationalities University, Dalian, China
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5
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Hartmann R, Fricke A, Stützel H, Mansourian S, Dekker T, Wohanka W, Alsanius B. Internalization of Escherichia coli O157:H7 gfp+ in rocket and Swiss chard baby leaves as affected by abiotic and biotic damage. Lett Appl Microbiol 2017; 65:35-41. [PMID: 28397273 DOI: 10.1111/lam.12742] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/26/2017] [Accepted: 03/26/2017] [Indexed: 11/29/2022]
Abstract
Internalization of human pathogens in edible parts of vegetables eaten raw is a major concern, since once internalized they are protected from sanitizing treatments. In this study, we examined the invasion of gfp-labelled Escherichia coli O157:H7 into intact and biotically (infection with Xanthomonas campestris/Pseudomonas syringae) and abiotically (grating with silicon carbide) damaged leaves of wild rocket (Diplotaxis tenuifolia) and Swiss chard (Beta vulgaris subsp. cicla) using laser scanning confocal microscopy. Bacterial cells were found in internal locations of the tissue, irrespective of tissue health status. Contaminated leaf sections of biotically and abiotically damaged wild rocket leaves showed higher susceptibility to microbial invasion, while the pathogen was internalized in greater numbers into intact Swiss chard leaf sections when abiotically, but not biotically, damaged. The greatest differences were observed between the plant species; after surface sanitization, E. coli O157:H7 was still detected in wild rocket leaves, but not in Swiss chard leaves. SIGNIFICANCE AND IMPACT OF THE STUDY Contamination of leafy vegetables with Escherichia coli O157:H7 is a growing problem, as reported outbreaks are increasing. However, establishment of this human pathogen in the phyllosphere is not completely understood. Using laser scanning confocal microscopy, we demonstrated that E. coli O157:H7gfp+ can invade plant tissue of Swiss chard and wild rocket leaves and that the bacterium is more sensitive to surface sanitization of Swiss chard leaves. Damage to leaf tissue promoted leaf invasion, but the nature of the damage (abiotic or biotic) and plant species had an impact.
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Affiliation(s)
- R Hartmann
- Department of Biosystems and Technology, Microbial Horticulture Unit, Swedish University of Agricultural Sciences, Alnarp, Sweden
- Institute of Horticultural Production Systems, Gottfried Wilhelm Leibniz Universität, Hannover, Germany
| | - A Fricke
- Institute of Horticultural Production Systems, Gottfried Wilhelm Leibniz Universität, Hannover, Germany
| | - H Stützel
- Institute of Horticultural Production Systems, Gottfried Wilhelm Leibniz Universität, Hannover, Germany
| | - S Mansourian
- Chemical Ecology Group, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - T Dekker
- Chemical Ecology Group, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - W Wohanka
- Department of Pomology, Geisenheim University, Geisenheim, Germany
| | - B Alsanius
- Department of Biosystems and Technology, Microbial Horticulture Unit, Swedish University of Agricultural Sciences, Alnarp, Sweden
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Ximenes E, Hoagland L, Ku S, Li X, Ladisch M. Human pathogens in plant biofilms: Formation, physiology, and detection. Biotechnol Bioeng 2017; 114:1403-1418. [PMID: 28067424 DOI: 10.1002/bit.26247] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 12/29/2022]
Affiliation(s)
- Eduardo Ximenes
- Laboratory of Renewable Resources Engineering; Purdue University; West Lafayette Indiana 47907-2022
- Department of Agricultural and Biological Engineering; Purdue University; West Lafayette Indiana
| | - Lori Hoagland
- Horticulture and Landscape Architecture; Purdue University; West Lafayette Indiana
| | - Seockmo Ku
- Laboratory of Renewable Resources Engineering; Purdue University; West Lafayette Indiana 47907-2022
- Department of Agricultural and Biological Engineering; Purdue University; West Lafayette Indiana
| | - Xuan Li
- Laboratory of Renewable Resources Engineering; Purdue University; West Lafayette Indiana 47907-2022
| | - Michael Ladisch
- Laboratory of Renewable Resources Engineering; Purdue University; West Lafayette Indiana 47907-2022
- Department of Agricultural and Biological Engineering; Purdue University; West Lafayette Indiana
- Weldon School of Biomedical Engineering; Purdue University; West Lafayette Indiana
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7
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Kalily E, Hollander A, Korin B, Cymerman I, Yaron S. Mechanisms of resistance to linalool inSalmonellaSenftenberg and their role in survival on basil. Environ Microbiol 2016; 18:3673-3688. [DOI: 10.1111/1462-2920.13268] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 02/14/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Emmanuel Kalily
- Faculty of Biotechnology and Food Engineering; and The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology; Haifa Israel
| | - Amit Hollander
- Faculty of Biotechnology and Food Engineering; and The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology; Haifa Israel
| | - Ben Korin
- Faculty of Biotechnology and Food Engineering; and The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology; Haifa Israel
| | - Itamar Cymerman
- Faculty of Biotechnology and Food Engineering; and The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology; Haifa Israel
| | - Sima Yaron
- Faculty of Biotechnology and Food Engineering; and The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology; Haifa Israel
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Sallach JB, Zhang Y, Hodges L, Snow D, Li X, Bartelt-Hunt S. Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2015; 197:269-277. [PMID: 25483595 DOI: 10.1016/j.envpol.2014.11.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/10/2014] [Accepted: 11/14/2014] [Indexed: 06/04/2023]
Abstract
The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce.
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Affiliation(s)
- J Brett Sallach
- University of Nebraska-Lincoln, Department of Civil Engineering, N104 SLNK, Lincoln, NE 68588-0531, USA
| | - Yuping Zhang
- University of Nebraska-Lincoln, Department of Civil Engineering, N104 SLNK, Lincoln, NE 68588-0531, USA
| | - Laurie Hodges
- University of Nebraska-Lincoln, Department of Agronomy and Horticulture, 377N PLSH, Lincoln, NE 68583-0724, USA.
| | - Daniel Snow
- University of Nebraska-Lincoln, Water Sciences Laboratory, 202 Water Sciences Laboratory, 1840 North 37th Street, Lincoln, NE 68583-0844, USA.
| | - Xu Li
- University of Nebraska-Lincoln, Department of Civil Engineering, N104 SLNK, Lincoln, NE 68588-0531, USA.
| | - Shannon Bartelt-Hunt
- University of Nebraska-Lincoln, Department of Civil Engineering, 203B Peter Kiewit Institute, Omaha, NE 68182-0178, USA.
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Marvasi M, Cox CE, Xu Y, Noel JT, Giovannoni JJ, Teplitski M. Differential regulation of Salmonella typhimurium genes involved in O-antigen capsule production and their role in persistence within tomato fruit. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:793-800. [PMID: 23489058 DOI: 10.1094/mpmi-09-12-0208-r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Enteric pathogens, including non-typhoidal Salmonella spp. and enterovirulent Escherichia coli, are capable of persisting and multiplying within plants. Yet, little is still known about the mechanisms of these interactions. This study identified the Salmonella yihT gene (involved in synthesis of the O-antigen capsule) as contributing to persistence in immature tomato fruit. Deletion of yihT reduced competitive fitness of S. enterica sv. Typhimurium in green (but not ripe, regardless of color) tomato fruit by approximately 3 logs. The yihT recombinase-based in vivo expression technology (RIVET) reporter was strongly activated in unripe tomato fruit, and fitness of the mutant inversely correlated with the level of the yihT gene expression. Expression of yihT in mature tomato fruit was low, and yihT did not affect competitive fitness within mature fruit. To better understand the molecular basis of the phenotype, behaviors of the yihT RIVET reporter and the yihT mutant were tested in tomato fruit defective in ethylene signaling. These experiments suggest a role for functional ethylene-mediated signaling in the persistence of Salmonella spp. within tomato fruit. Furthermore, jasmonic acid and its precursors strongly reduced expression of yihT.
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Affiliation(s)
- Massimiliano Marvasi
- Soil and Water Science Department, Genetics Institute Rm330E, 2033 Mowry Rd, University of Florida-IFAS, Gainesville 32611, USA
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Fletcher J, Leach JE, Eversole K, Tauxe R. Human pathogens on plants: designing a multidisciplinary strategy for research. PHYTOPATHOLOGY 2013; 103:306-315. [PMID: 23406434 DOI: 10.1094/phyto-09-12-0236-ia] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent efforts to address concerns about microbial contamination of food plants and resulting foodborne illness have prompted new collaboration and interactions between the scientific communities of plant pathology and food safety. This article provides perspectives from scientists of both disciplines and presents selected research results and concepts that highlight existing and possible future synergisms for audiences of both disciplines. Plant pathology is a complex discipline that encompasses studies of the dissemination, colonization, and infection of plants by microbes such as bacteria, viruses, fungi, and oomycetes. Plant pathologists study plant diseases as well as host plant defense responses and disease management strategies with the goal of minimizing disease occurrences and impacts. Repeated outbreaks of human illness attributed to the contamination of fresh produce, nuts and seeds, and other plant-derived foods by human enteric pathogens such as Shiga toxin-producing Escherichia coli and Salmonella spp. have led some plant pathologists to broaden the application of their science in the past two decades, to address problems of human pathogens on plants (HPOPs). Food microbiology, which began with the study of microbes that spoil foods and those that are critical to produce food, now also focuses study on how foods become contaminated with pathogens and how this can be controlled or prevented. Thus, at the same time, public health researchers and food microbiologists have become more concerned about plant-microbe interactions before and after harvest. New collaborations are forming between members of the plant pathology and food safety communities, leading to enhanced research capacity and greater understanding of the issues for which research is needed. The two communities use somewhat different vocabularies and conceptual models. For example, traditional plant pathology concepts such as the disease triangle and the disease cycle can help to define cross-over issues that pertain also to HPOP research, and can suggest logical strategies for minimizing the risk of microbial contamination. Continued interactions and communication among these two disciplinary communities is essential and can be achieved by the creation of an interdisciplinary research coordination network. We hope that this article, an introduction to the multidisciplinary HPOP arena, will be useful to researchers in many related fields.
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Affiliation(s)
- Jacqueline Fletcher
- Department of Entomology & Plant Pathology, Oklahoma State University, Stillwater, OK, USA.
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Brandl MT, Cox CE, Teplitski M. Salmonella interactions with plants and their associated microbiota. PHYTOPATHOLOGY 2013; 103:316-325. [PMID: 23506360 DOI: 10.1094/phyto-11-12-0295-rvw] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The increase in the incidence of gastroenteritis outbreaks linked to the consumption of foods of plant origin has ignited public concern and scientific interest in understanding interactions of human enteric pathogens with plants. Enteric disease caused by nontyphoidal Salmonella is a major public health burden, with the number of cases of illness linked to fresh produce, spices, and nuts surpassing those linked to foods of animal origin. Mounting evidence supports the hypothesis that colonization of plants is an important part of the life cycle of this human pathogen. Although plant responses to human pathogens are distinct from the more specific responses to phytopathogens, plants appear to recognize Salmonella, likely by detecting conserved microbial patterns, which subsequently activates basal defenses. Numerous Salmonella genes have been identified as playing a role in its colonization of plant surfaces and tissues, and in its various interactions with other members of the phyto-microbial community. Importantly, Salmonella utilizes diverse and overlapping strategies to interact with plants and their microflora, and to successfully colonize its vertebrate hosts. This review provides insight into the complex behavior of Salmonella on plants and the apparent remarkable adaptation of this human pathogen to a potentially secondary host.
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Kwan G, Charkowski AO, Barak JD. Salmonella enterica suppresses Pectobacterium carotovorum subsp. carotovorum population and soft rot progression by acidifying the microaerophilic environment. mBio 2013; 4:e00557-12. [PMID: 23404399 PMCID: PMC3573663 DOI: 10.1128/mbio.00557-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 01/11/2013] [Indexed: 12/02/2022] Open
Abstract
UNLABELLED Although enteric human pathogens are usually studied in the context of their animal hosts, a significant portion of their life cycle occurs on plants. Plant disease alters the phyllosphere, leading to enhanced growth of human pathogens; however, the impact of human pathogens on phytopathogen biology and plant health is largely unknown. To characterize the interaction between human pathogens and phytobacterial pathogens in the phyllosphere, we examined the interactions between Pectobacterium carotovorum subsp. carotovorum and Salmonella enterica or Escherichia coli O157:H7 with regard to bacterial populations, soft rot progression, and changes in local pH. The presence of P. carotovorum subsp. carotovorum enhanced the growth of both S. enterica and E. coli O157:H7 on leaves. However, in a microaerophilic environment, S. enterica reduced P. carotovorum subsp. carotovorum populations and soft rot progression by moderating local environmental pH. Reduced soft rot was not due to S. enterica proteolytic activity. Limitations on P. carotovorum subsp. carotovorum growth, disease progression, and pH elevation were not observed on leaves coinoculated with E. coli O157:H7 or when leaves were coinoculated with S. enterica in an aerobic environment. S. enterica also severely undermined the relationship between the phytobacterial population and disease progression of a P. carotovorum subsp. carotovorum budB mutant defective in the 2,3-butanediol pathway for acid neutralization. Our results show that S. enterica and E. coli O157:H7 interact differently with the enteric phytobacterial pathogen P. carotovorum subsp. carotovorum. S. enterica inhibition of soft rot progression may conceal a rapidly growing human pathogen population. Whereas soft rotted produce can alert consumers to the possibility of food-borne pathogens, healthy-looking produce may entice consumption of contaminated vegetables. IMPORTANCE Salmonella enterica and Escherichia coli O157:H7 may use plants to move between animal and human hosts. Their populations are higher on plants cocolonized with the common bacterial soft rot pathogen Pectobacterium carotovorum subsp. carotovorum, turning edible plants into a risk factor for human disease. We inoculated leaves with P. carotovorum subsp. carotovorum and S. enterica or E. coli O157:H7 to study the interactions between these bacteria. While P. carotovorum subsp. carotovorum enhanced the growth of both S. enterica and E. coli O157:H7, these human pathogens affected P. carotovorum subsp. carotovorum fundamentally differently. S. enterica reduced P. carotovorum subsp. carotovorum growth and acidified the environment, leading to less soft rot on leaves; E. coli O157:H7 had no such effects. As soft rot signals a food safety risk, the reduction of soft rot symptoms in the presence of S. enterica may lead consumers to eat healthy-looking but S. enterica-contaminated produce.
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Affiliation(s)
- Grace Kwan
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Sant'Ana AS, Barbosa MS, Destro MT, Landgraf M, Franco BDGM. Growth potential of Salmonella spp. and Listeria monocytogenes in nine types of ready-to-eat vegetables stored at variable temperature conditions during shelf-life. Int J Food Microbiol 2012; 157:52-8. [PMID: 22561064 DOI: 10.1016/j.ijfoodmicro.2012.04.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/23/2012] [Accepted: 04/15/2012] [Indexed: 12/01/2022]
Abstract
Growth potential (δ) is defined as the difference between the population of a microorganism at the end of shelf-life of specific food and its initial population. The determination of δ of Salmonella and Listeria monocytogenes in RTE vegetables can be very useful to determine likely threats to food safety. However, little is known on the behavior of these microorganisms in several RTE vegetables. Therefore, the aim of this study was to determine the δ of both pathogens in nine different types of RTE vegetables (escarole, collard green, spinach, watercress, arugula, grated carrot, green salad, and mix for yakisoba) stored at refrigeration (7°C) and abuse temperature (15°C). The population of aerobic microorganisms and lactic acid bacteria, including those showing antimicrobial activity has been also determined. Results indicated that L. monocytogenes was able to grow (δ≥0.5 log(10)) in more storage conditions and vegetables than Salmonella. Both microorganisms were inhibited in carrots, although a more pronounced effect has been observed against L. monocytogenes. The highest δ values were obtained when the RTE vegetables were stored 15°C/6days in collard greens (δ=3.3) and arugula (δ=3.2) (L. monocytogenes) and arugula (δ=4.1) and escarole (δ=2.8) (Salmonella). In most vegetables and storage conditions studied, the counts of total aerobic microorganisms raised significantly independent of the temperature of storage (p<0.05). Counts of lactic acid bacteria were higher in vegetables partially or fully stored at abuse temperature with recovery of isolates showing antimicrobial activity. In conclusion, the results of this study show that Salmonella and L. monocytogenes may grow and reach high populations in RTE vegetables depending on storage conditions and the definition of effective intervention strategies are needed to control their growth in these products.
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Affiliation(s)
- Anderson S Sant'Ana
- Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP - Brazil.
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14
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de Souza Sant'Ana A. Introduction to the Special Issue: Salmonella in foods: Evolution, strategies and challenges. Food Res Int 2012. [DOI: 10.1016/j.foodres.2012.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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