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Truschi S, Marini L, Cacciari I, Baldi A, Bruschi P, Lenzi A, Baales J, Zeisler-Diehl VV, Schreiber L, Marvasi M. Relationship between Salmonella enterica attachment and leaf hydrophobicity, roughness, and epicuticular waxes: a focus on 30 baby-leaf salads. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2024. [PMID: 39030951 DOI: 10.1002/jsfa.13751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/23/2024] [Accepted: 07/04/2024] [Indexed: 07/22/2024]
Abstract
BACKGROUND The first step in the contamination of leafy vegetables by human pathogens is their attachment to the leaf surface. The success of this is influenced strongly by the physical and chemical characteristics of the surface itself (number and size of stomata, presence of trichomes and veins, epicuticular waxes, hydrophobicity, etc.). This study evaluated the attachment of Salmonella enterica to 30 baby-leaf salads and tested whether the differences found among them were related to the following leaf traits: hydrophobicity, roughness, and epicuticular waxes. RESULTS Differences in susceptibility to contamination by S. enterica were found between the 30 baby-leaf salads investigated. The lowest attachment was found in wild lettuce (Lactuca serriola L.) and lamb's lettuce 'Trophy F1' (Valerianella locusta [L.] Laterr.), with values of 1.63 ± 0.39 Log(CFU/cm2) and 1.79 ± 0.54 Log(CFU/cm2), respectively. Attachment was correlated with hydrophobicity (measured as contact angle) (r = -0.39) and epicuticular waxes (r = -0.81) but not with roughness (r = 0.24). The most important wax components for attachment were alcohols and, in particular, the three-dimensional (3D) wax crystals of C26 alcohol, but fatty acids probably also had a role. Both these compounds increased hydrophobicity. The presence of thymol, whose antimicrobial properties are well known, was found in lamb's lettuce. CONCLUSIONS The findings of this study can help to predict and control the attachment and contamination of leafy salads by enterobacteria. They also provide useful information for breeding programs aiming to develop cultivars that are less susceptible to human pathogens, enhancing the food safety of vegetables. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Stefania Truschi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Lorenzo Marini
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Ilaria Cacciari
- CNR, Institute of Applied Physics 'Nello Carrara', Sesto Fiorentino, Italy
| | - Ada Baldi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Piero Bruschi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Anna Lenzi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Johanna Baales
- Institute of Cellular and Molecular Botany (IZMB), University of Bonn, Bonn, Germany
| | | | - Lukas Schreiber
- Institute of Cellular and Molecular Botany (IZMB), University of Bonn, Bonn, Germany
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Woodford L, Fellows R, White HL, Ormsby MJ, Quilliam RS. Salmonella Typhimurium and Vibrio cholerae can be transferred from plastic mulch to basil and spinach salad leaves. Heliyon 2024; 10:e31343. [PMID: 38818200 PMCID: PMC11137414 DOI: 10.1016/j.heliyon.2024.e31343] [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: 05/06/2024] [Revised: 05/14/2024] [Accepted: 05/14/2024] [Indexed: 06/01/2024] Open
Abstract
Plastic pollution is increasingly found in agricultural environments, where it contaminates soil and crops. Microbial biofilms rapidly colonise environmental plastics, such as the plastic mulches used in agricultural systems, which provide a unique environment for microbial plastisphere communities. Human pathogens can also persist in the plastisphere, and enter agricultural environments via flooding or irrigation with contaminated water. In this study we examined whether Salmonella Typhimurium and Vibrio cholerae can be transferred from the plastisphere on plastic mulch to the surface of ready-to-eat crop plants, and subsequently persist on the leaf surface. Both S. Typhimurium and V. cholerae were able to persist for 14 days on fragments of plastic mulch adhering to the surface of leaves of both basil and spinach. Importantly, within 24 h both pathogens were capable of dissociating from the surface of the plastic and were transferred onto the surface of both basil and spinach leaves. This poses a further risk to food safety and human health, as even removal of adhering plastics and washing of these ready-to-eat crops would not completely remove these pathogens. As the need for more intensive food production increases, so too does the use of plastic mulches in agronomic systems. Therefore, there is now an urgent need to understand the unquantified co-pollutant pathogen risk of contaminating agricultural and food production systems with plastic pollution.
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Affiliation(s)
- Luke Woodford
- Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Rosie Fellows
- Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Hannah L. White
- Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Michael J. Ormsby
- Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Richard S. Quilliam
- Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
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Kong Y, Deering AJ, Nemali K. Minimizing Escherichia coli O157:H7 contamination in indoor farming: effects of cultivar type and ultra-violet light quality. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2024; 104:4218-4225. [PMID: 38294189 DOI: 10.1002/jsfa.13303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 10/31/2023] [Accepted: 01/07/2024] [Indexed: 02/01/2024]
Abstract
BACKGROUND Bacterial contamination of produce is a concern in indoor farming due to close plant spacing, recycling irrigation, warm temperatures, and high relative humidity during production. Cultivars that inherently resist contamination and photo-sanitization using ultraviolet (UV) radiation during the production phase can reduce bacterial contamination. However, there is limited information to support their use in indoor farming. RESULTS Lettuce (Lactuca sativa) cultivars with varying plant architectures grown in a custom-built indoor farm exhibited differences in E. coli O157:H7 survival after inoculation. The survival of E. coli O157:H7 was lowest in the leaf cultivar (open architecture) and highest in the romaine and oakleaf cultivars (compact architecture). Of the different UV wavelengths that were tested (UV-A, UV-A + B, UV-A + C), UV A + C at an intensity of 54.5 μmol m-2 s-1 (with 3.5 μmol m-2 s-1 of UV-C), provided for 15 min every day, was found to be most efficacious in reducing the E. coli O157:H7 survival on romaine lettuce with no negative effects on plant growth and quality. CONCLUSION Contamination of E. coli O157:H7 on lettuce plants can be reduced and the food safety levels in indoor farms can be increased by selecting cultivars with an open leaf architecture coupled with photo-sanitization using low and frequent exposure to UV A + C radiation. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Yuyao Kong
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, USA
| | - Amanda J Deering
- Department of Food Science, Purdue University, West Lafayette, IN, USA
| | - Krishna Nemali
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, USA
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4
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Ding Q, Gu G, Nou X, Micallef SA. Cultivar was more influential than bacterial strain and other experimental factors in recovery of Escherichia coli O157:H7 populations from inoculated live Romaine lettuce plants. Microbiol Spectr 2024; 12:e0376723. [PMID: 38363139 PMCID: PMC10986467 DOI: 10.1128/spectrum.03767-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/22/2024] [Indexed: 02/17/2024] Open
Abstract
The varied choice of bacterial strain, plant cultivar, and method used to inoculate, retrieve, and enumerate Escherichia coli O157:H7 from live plants could affect comparability among studies evaluating lettuce-enterobacterial interactions. Cultivar, bacterial strain, incubation time, leaf side inoculated, and sample processing method were assessed for their influence in recovering and quantifying E. coli O157:H7 from live Romaine lettuce. Cultivar exerted the strongest effect on E. coli O157:H7 counts, which held up even when cultivar was considered in interactions with other factors. Recovery from the popularly grown green Romaine "Rio Bravo" was higher than from the red variety "Outredgeous." Other modulating variables were incubation time, strain, and leaf side inoculated. Sample processing method was not significant. Incubation for 24 hours post-lettuce inoculation yielded greater counts than 48 hours, but was affected by lettuce cultivar, bacterial strain, and leaf side inoculated. Higher counts obtained for strain EDL933 compared to a lettuce outbreak strain 2705C emphasized the importance of selecting relevant strains for the system being studied. Inoculating the abaxial side of leaves gave higher counts than adaxial surface inoculation, although this factor interacted with strain and incubation period. Our findings highlight the importance of studying interactions between appropriate bacterial strains and plant cultivars for more relevant research results, and of standardizing inoculation and incubation procedures. The strong effect of cultivar exerted on the E. coli O157:H7-lettuce association supports the need to start reporting cultivar information for illness outbreaks to facilitate the identification and study of plant traits that impact food safety risk.IMPORTANCEThe contamination of Romaine lettuce with Escherichia coli O157:H7 has been linked to multiple foodborne disease outbreaks, but variability in the methods used to evaluate E. coli O157:H7 association with live lettuce plants complicates the comparability of different studies. In this study, various experimental variables and sample processing methods for recovering and quantifying E. coli O157:H7 from live Romaine lettuce were assessed. Cultivar was found to exert the strongest influence on E. coli O157:H7 retrieval from lettuce. Other modulating factors were bacterial incubation time on plants, strain, and leaf side inoculated, while sample processing method had no impact. Our findings highlight the importance of selecting relevant cultivars and strains, and of standardizing inoculation and incubation procedures, in these types of assessments. Moreover, results support the need to start reporting cultivars implicated in foodborne illness outbreaks to facilitate the identification and study of plant traits that impact food safety risk.
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Affiliation(s)
- Qiao Ding
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland, USA
| | - Ganyu Gu
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, Maryland, USA
| | - Xiangwu Nou
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, Maryland, USA
| | - Shirley A. Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland, USA
- Center for Food Safety and Security Systems, University of Maryland, College Park, Maryland, USA
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5
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Yuan J, Yang L, Yu P, Tang N, Liu L, Wang W, Wang P, Yang Q, Guo S, Li J. Comparison and development of scanning electron microscope techniques for delicate plant tissues. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 340:111963. [PMID: 38103698 DOI: 10.1016/j.plantsci.2023.111963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023]
Abstract
Cell deformation often occurs during sample preparation and imaging with scanning electron microscope (SEM), especially with delicate samples, which influences the accuracy of the results. Here we investigate the influence of several preparation methods on cell deformation, using water content and tissue hardness as indicators to classify "delicate" samples of plant species. The degree of deformation in samples resulting from five preparation methods was measured at the tissue and single-cell levels, revealing that a cryo- and methanol-fixation produced lower degrees of tissue dimension deformation and better preservation of cell shape for delicate samples, while for harder tissues, other preparation methods for a dehydrated specimen are also suitable. Stability and image quality of delicate samples could be improved with the application of a cryo-protectant combined with a lower cryo-stage temperature, e.g. - 30 °C. We show that the sample stability under the beam was improved by combining larger sample size and cryo-stage application. Furthermore, the influence of adaxial and abaxial tissue surfaces, the accelerating voltage, and sputter coating time on sample stability and image quality was evaluated. Our study is valuable for artifact reduction and easy application of SEM.
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Affiliation(s)
- Jinhong Yuan
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Lin Yang
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Panpan Yu
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Na Tang
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Le Liu
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Wenke Wang
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Pei Wang
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China
| | - Qingxiang Yang
- Henan International Joint Laboratory of Agricultural Microbial Ecology and Technology, Xinxiang 453007, China
| | - Siyi Guo
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Junhua Li
- Engineering Research Center of Crop Genetic Improvement and Germplasm Innovation in Henan Province, College of Life Sciences, Henan Normal University, Xinxiang 453007, China.
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6
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Thomas GA, Paradell Gil T, Müller CT, Rogers HJ, Berger CN. From field to plate: How do bacterial enteric pathogens interact with ready-to-eat fruit and vegetables, causing disease outbreaks? Food Microbiol 2024; 117:104389. [PMID: 37919001 DOI: 10.1016/j.fm.2023.104389] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 09/11/2023] [Accepted: 09/17/2023] [Indexed: 11/04/2023]
Abstract
Ready-to-eat fruit and vegetables are a convenient source of nutrients and fibre for consumers, and are generally safe to eat, but are vulnerable to contamination with human enteric bacterial pathogens. Over the last decade, Salmonella spp., pathogenic Escherichia coli, and Listeria monocytogenes have been linked to most of the bacterial outbreaks of foodborne illness associated with fresh produce. The origins of these outbreaks have been traced to multiple sources of contamination from pre-harvest (soil, seeds, irrigation water, domestic and wild animal faecal matter) or post-harvest operations (storage, preparation and packaging). These pathogens have developed multiple processes for successful attachment, survival and colonization conferring them the ability to adapt to multiple environments. However, these processes differ across bacterial strains from the same species, and across different plant species or cultivars. In a competitive environment, additional risk factors are the plant microbiome phyllosphere and the plant responses; both factors directly modulate the survival of the pathogens on the leaf's surface. Understanding the mechanisms involved in bacterial attachment to, colonization of, and proliferation, on fresh produce and the role of the plant in resisting bacterial contamination is therefore crucial to reducing future outbreaks.
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Affiliation(s)
- Gareth A Thomas
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Teresa Paradell Gil
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Carsten T Müller
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Hilary J Rogers
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK
| | - Cedric N Berger
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK.
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7
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An J, Sun L, Liu M, Dai R, Ge G, Wang Z, Jia Y. Influences of Growth Stage and Ensiling Time on Fermentation Characteristics, Nitrite, and Bacterial Communities during Ensiling of Alfalfa. PLANTS (BASEL, SWITZERLAND) 2023; 13:84. [PMID: 38202392 PMCID: PMC10780930 DOI: 10.3390/plants13010084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/05/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024]
Abstract
This study examined the impacts of growth stage and ensiling duration on the fermentation characteristics, nitrite content, and bacterial communities during the ensiling of alfalfa. Harvested alfalfa was divided into two groups: vegetative growth stage (VG) and late budding stage (LB). The fresh alfalfa underwent wilting until reaching approximately 65% moisture content, followed by natural fermentation. The experiment followed a completely randomized design, with samples collected after the wilting of alfalfa raw materials (MR) and on days 1, 3, 5, 7, 15, 30, and 60 of fermentation. The growth stage significantly influenced the chemical composition of alfalfa, with crude protein content being significantly higher in the vegetative growth stage alfalfa compared to that in the late budding stage (p < 0.05). Soluble carbohydrates, neutral detergent fiber, and acid detergent fiber content were significantly lower in the vegetative growth stage compared to the late budding stage (p < 0.05). Nitrite content, nitrate content, nitrite reductase activity, and nitrate reductase activity were all significantly higher in the vegetative growth stage compared to the late budding stage (p < 0.05). In terms of fermentation parameters, silage from the late budding stage exhibited superior characteristics compared to that from the vegetative growth stage. Compared to the alfalfa silage during the vegetative growth stage, the late budding stage group exhibited a higher lactate content and lower pH level. Notably, butyric acid was only detected in the silage from the vegetative growth stage group. Throughout the ensiling process, nitrite content, nitrate levels, nitrite reductase activity, and nitrate reductase activity decreased in both treatment groups. The dominant lactic acid bacteria differed between the two groups, with Enterococcus being predominant in vegetative growth stage alfalfa silage, and Weissella being predominant in late budding stage silage, transitioning to Lactiplantibacillus in the later stages of fermentation. On the 3rd day of silage fermentation, the vegetative growth stage group exhibited the highest abundance of Enterococcus, which subsequently decreased to its lowest level on the 15th day. Correlation analysis revealed that lactic acid bacteria, including Limosilactobacillus, Levilactobacillus, Loigolactobacillus, Pediococcus, Lactiplantibacillus, and Weissella, played a key role in nitrite and nitrate degradation in alfalfa silage. The presence of nitrite may be linked to Erwinia, unclassified_o__Enterobacterales, Pantoea, Exiguobacterium, Enterobacter, and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium.
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Affiliation(s)
- Jiangbo An
- Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot 010019, China; (J.A.); (M.L.); (R.D.); (G.G.); (Z.W.)
- Key Laboratory of Grassland Resources, Ministry of Education, Inner Mongolia Agricultural University, Hohhot 010019, China
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010019, China
| | - Lin Sun
- Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China;
| | - Mingjian Liu
- Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot 010019, China; (J.A.); (M.L.); (R.D.); (G.G.); (Z.W.)
- Key Laboratory of Grassland Resources, Ministry of Education, Inner Mongolia Agricultural University, Hohhot 010019, China
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010019, China
| | - Rui Dai
- Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot 010019, China; (J.A.); (M.L.); (R.D.); (G.G.); (Z.W.)
- Key Laboratory of Grassland Resources, Ministry of Education, Inner Mongolia Agricultural University, Hohhot 010019, China
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010019, China
| | - Gentu Ge
- Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot 010019, China; (J.A.); (M.L.); (R.D.); (G.G.); (Z.W.)
- Key Laboratory of Grassland Resources, Ministry of Education, Inner Mongolia Agricultural University, Hohhot 010019, China
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010019, China
| | - Zhijun Wang
- Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot 010019, China; (J.A.); (M.L.); (R.D.); (G.G.); (Z.W.)
- Key Laboratory of Grassland Resources, Ministry of Education, Inner Mongolia Agricultural University, Hohhot 010019, China
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010019, China
| | - Yushan Jia
- Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization, Ministry of Agriculture, Inner Mongolia Agricultural University, Hohhot 010019, China; (J.A.); (M.L.); (R.D.); (G.G.); (Z.W.)
- Key Laboratory of Grassland Resources, Ministry of Education, Inner Mongolia Agricultural University, Hohhot 010019, China
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010019, China
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Zhang H, Zhai Y, Chen K, Shi H. Adhesion of Escherichia coli O157:H7 during sublethal injury and resuscitation: Importance of pili and surface properties. Food Microbiol 2023; 115:104329. [PMID: 37567635 DOI: 10.1016/j.fm.2023.104329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 06/19/2023] [Accepted: 06/19/2023] [Indexed: 08/13/2023]
Abstract
Escherichia coli O157:H7 can recover from sublethally injured (SI) state, which causes threat of foodborne illness. Adhesion plays a key role in the carriage of pathogens in food. In this study, we investigated the adhesion ability of SI and recovered E. coli O157:H7 wildtype and its three pili-deficient mutants (curli, type 1 fimbriae, and type IV pili) on six food-related surfaces. Plate counting was used to determine adhesion population after washing and oscillating the surfaces. Spinach exhibited the stronger adhesion population of E. coli O157:H7 than the other fresh produces (p < 0.05). In addition, at least one key pili dominated adhesion on these surfaces, and curli was always included. The adhesion population and contribution of different types of pili were jointly affected by surface and physiological state. This can be attributed to high hydrophobicity and positive charge density on surface and different expression levels of csgB, fimA, fimC and ppdD in SI and recovered cells. Among glucose, mannose, maltose, fructose, lactose, and sucrose, addition of 0.5% mannose could reduce adhesion of cells at all physiological states on stainless steel. Overall, this research will provide support for controlling adhesion of SI and recovered E. coli O157:H7.
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Affiliation(s)
- Hongchen Zhang
- College of Food Science, Southwest University, Chongqing, China
| | - Yujun Zhai
- College of Food Science, Southwest University, Chongqing, China
| | - Kewei Chen
- College of Food Science, Southwest University, Chongqing, China
| | - Hui Shi
- College of Food Science, Southwest University, Chongqing, China.
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9
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Lin C, Li LJ, Ren K, Zhou SYD, Isabwe A, Yang LY, Neilson R, Yang XR, Cytryn E, Zhu YG. Phagotrophic protists preserve antibiotic-resistant opportunistic human pathogens in the vegetable phyllosphere. ISME COMMUNICATIONS 2023; 3:94. [PMID: 37660098 PMCID: PMC10475086 DOI: 10.1038/s43705-023-00302-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 09/04/2023]
Abstract
Food safety of leafy greens is an emerging public health issue as they can harbor opportunistic human pathogens (OHPs) and expose OHPs to consumers. Protists are an integral part of phyllosphere microbial ecosystems. However, our understanding of protist-pathogen associations in the phyllosphere and their consequences on public health remains poor. Here, we examined phyllosphere protists, human pathogen marker genes (HPMGs), and protist endosymbionts from four species of leafy greens from major supermarkets in Xiamen, China. Our results showed that Staphylococcus aureus and Klebsiella pneumoniae were the dominant human pathogens in the vegetable phyllosphere. The distribution of HPMGs and protistan communities differed between vegetable species, of which Chinese chive possessed the most diverse protists and highest abundance of HPMGs. HPMGs abundance positively correlated with the diversity and relative abundance of phagotrophic protists. Whole genome sequencing further uncovered that most isolated phyllosphere protists harbored multiple OHPs which carried antibiotic resistance genes, virulence factors, and metal resistance genes and had the potential to HGT. Colpoda were identified as key phagotrophic protists which positively linked to OHPs and carried diverse resistance and virulence potential endosymbiont OHPs including Pseudomonas nitroreducens, Achromobacter xylosoxidans, and Stenotrophomonas maltophilia. We highlight that phyllosphere protists contribute to the transmission of resistant OHPs through internalization and thus pose risks to the food safety of leafy greens and human health. Our study provides insights into the protist-OHP interactions in the phyllosphere, which will help in food safety surveillance and human health.
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Affiliation(s)
- Chenshuo Lin
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Li-Juan Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Kexin Ren
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
| | - Shu-Yi-Dan Zhou
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, 510650, China
| | - Alain Isabwe
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
| | - Le-Yang Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, 100049, Beijing, China
| | - Roy Neilson
- Ecological Sciences, The James Hutton Institute, Dundee, DD2 5DA, Scotland, UK
| | - Xiao-Ru Yang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China
| | - Eddie Cytryn
- Department of Soil Chemistry, Plant Nutrition and Microbiology, Institute of Soil, Water and Environmental Sciences, The Volcani Institute, Agriculture Research Organization, 7528809, Rishon Lezion, Israel
| | - Yong-Guan Zhu
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, China.
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China.
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Zhao J, Liu HP, Yin XJ, Dong ZH, Wang SR, Li JF, Shao T. Dynamics of Phyllosphere Microbiota and Chemical Parameters at Various Growth Stages and Their Contribution to Anaerobic Fermentation of Pennisetum giganteum. Microbiol Spectr 2023; 11:e0228822. [PMID: 37010418 PMCID: PMC10269755 DOI: 10.1128/spectrum.02288-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 02/28/2023] [Indexed: 04/04/2023] Open
Abstract
This work evaluated the dynamic changes of phyllosphere microbiota and chemical parameters at various growth stages of Pennisetum giganteum and their effects on the bacterial community, cooccurrence networks, and functional properties during anaerobic fermentation. P. giganteum was collected at two growth stages (early vegetative stage [PA] and late vegetative stage [PB]) and was naturally fermented (NPA and NPB) for 1, 3, 7, 15, 30, and 60 days, respectively. At each time point, NPA or NPB was randomly sampled for the analysis of chemical composition, fermentation parameter, and microbial number. In addition, the fresh, 3-day, and 60-day NPA and NPB were subjected to high-throughput sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional prediction analyses. Growth stage obviously affected the phyllosphere microbiota and chemical parameters of P. giganteum. After 60 days of fermentation, NPB had a higher lactic acid concentration and ratio of lactic acid to acetic acid but a lower pH value and ammonia nitrogen concentration than NPA. Weissella and Enterobacter were dominant in 3-day NPA and Weissella was dominant in 3-day NPB, while Lactobacillus was the most abundant genus in both 60-day NPA and NPB. The complexity of bacterial cooccurrence networks in the phyllosphere decreased with P. giganteum growth. The ensiling process further decreased the complexity of bacterial networks, with the simplest bacterial correlation structures in NPB. There were great differences in the KEGG functional profiles of PA and PB. Ensiling promoted the metabolism of lipid, cofactors, vitamins, energy, and amino acids but suppressed the metabolism of carbohydrates and nucleotides. Storage time had a greater influence than growth stage on bacterial community diversity, cooccurrence networks, and functional profiles of P. giganteum silage. Differences in bacterial diversity and functionality of P. giganteum silage caused by growth stage appear to be offset by long-term storage. IMPORTANCE The phyllosphere microbiota consists of various and complex microbes, including bacteria with crucial relevance to the quality and safety of fermented food and feed. It initially derives from soil and becomes specific to its host after interaction with plants and climate. Bacteria associated with the phyllosphere are highly abundant and diverse, but we know little about their succession. Here, the phyllospheric microbiota structure was analyzed within the growth of P. giganteum. We also evaluated the effects of phyllosphere microbiota and chemical parameter changes on the anaerobic fermentation of P. giganteum. We observed remarkable differences in bacterial diversity, cooccurrence, and functionality of P. giganteum at various growth stages and storage times. The obtained results are important for understanding the fermentation mechanism and may contribute to high-efficient production without additional cost.
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Affiliation(s)
- Jie Zhao
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Hao-Peng Liu
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Xue-Jing Yin
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Zhi-Hao Dong
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Si-Ran Wang
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Jun-Feng Li
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Tao Shao
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
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Wang S, Wang Y, Li J, Dong Z, Zhao J, Nazar M, Kaka NA, Shao T. Assessing the impact of phyllosphere microbiota on dynamics of in-silo fermentation of Italian ryegrass harvested at heading and blooming stages. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2023; 103:3272-3286. [PMID: 36810766 DOI: 10.1002/jsfa.12516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/17/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND The present study aimed to investigate the relationship between the phyllosphere microbiota of Italian ryegrass (Lolium multiflorum Lam.) harvested at heading (H) [> 50% earing rate or 216 g kg-1 fresh weight (FW)] and blooming (B) (> 50% bloom or 254 g kg-1 FW) stages and in-silo fermentation products, and the composition, abundance, diversity and activity of bacterial community. In total, 72 (4 treatments × 6 ensiling durations × 3 replicates) laboratory scale (400 g) silages of Italian ryegrass were prepared: (i) irradiated heading stage silages (IRH) (n = 36) were inoculated with phyllosphere microbiota inoculum (2 mL) eluted from fresh Italian ryegrass at either heading (IH) (n = 18) or blooming (IB) (n = 18) stages; (ii) irradiated blooming stage silages (IRB) (n = 36) were inoculated with either IH (n = 18) or IB (n = 18). Triplicate silos of each treatment were analyzed after 1, 3, 7, 15, 30 and 60 days of ensiling. RESULTS In fresh forage, Enterobacter, Exiguobacterium and Pantoea were the three major genera at heading stage, and Rhizobium, Weissella and Lactococcus were the most abundant genera at blooming stage. Higher metabolic activity was found in IB. After 3 days of ensiling, the large amounts of lactic acid in IRH-IB and IRB-IB can be attributed to the higher abundances of Pediococcus and Lactobacillus, 1-phosphofructokinase, fructokinase, l-lactate dehydrogenase and glycolysis I, II and III. CONCLUSION The composition, abundance, diversity and functionality of the phyllosphere microbiota of Italian ryegrass at different growth stages could remarkably affect silage fermentation characteristics. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Siran Wang
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Yuxin Wang
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Junfeng Li
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Zhihao Dong
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Jie Zhao
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Mudasir Nazar
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Niaz Ali Kaka
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Tao Shao
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
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Esmael A, Al-Hindi RR, Albiheyri RS, Alharbi MG, Filimban AAR, Alseghayer MS, Almaneea AM, Alhadlaq MA, Ayubu J, Teklemariam AD. Fresh Produce as a Potential Vector and Reservoir for Human Bacterial Pathogens: Revealing the Ambiguity of Interaction and Transmission. Microorganisms 2023; 11:microorganisms11030753. [PMID: 36985326 PMCID: PMC10056104 DOI: 10.3390/microorganisms11030753] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
The consumer demand for fresh produce (vegetables and fruits) has considerably increased since the 1980s for more nutritious foods and healthier life practices, particularly in developed countries. Currently, several foodborne outbreaks have been linked to fresh produce. The global rise in fresh produce associated with human infections may be due to the use of wastewater or any contaminated water for the cultivation of fruits and vegetables, the firm attachment of the foodborne pathogens on the plant surface, and the internalization of these agents deep inside the tissue of the plant, poor disinfection practices and human consumption of raw fresh produce. Several investigations have been established related to the human microbial pathogens (HMPs) interaction, their internalization, and survival on/within plant tissue. Previous studies have displayed that HMPs are comprised of several cellular constituents to attach and adapt to the plant’s intracellular niches. In addition, there are several plant-associated factors, such as surface morphology, nutrient content, and plant–HMP interactions, that determine the internalization and subsequent transmission to humans. Based on documented findings, the internalized HMPs are not susceptible to sanitation or decontaminants applied on the surface of the fresh produce. Therefore, the contamination of fresh produce by HMPs could pose significant food safety hazards. This review provides a comprehensive overview of the interaction between fresh produce and HMPs and reveals the ambiguity of interaction and transmission of the agents to humans.
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Affiliation(s)
- Ahmed Esmael
- Botany and Microbiology Department, Faculty of Science, Benha University, Benha 13518, Egypt
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
- Correspondence: (A.E.); (R.R.A.)
| | - Rashad R. Al-Hindi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Correspondence: (A.E.); (R.R.A.)
| | - Raed S. Albiheyri
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Mona G. Alharbi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Amani A. R. Filimban
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Mazen S. Alseghayer
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Monitoring and Risk Assessment Department, Saudi Food and Drug Authority, Riyadh 13513, Saudi Arabia
| | - Abdulaziz M. Almaneea
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Monitoring and Risk Assessment Department, Saudi Food and Drug Authority, Riyadh 13513, Saudi Arabia
| | - Meshari Ahmed Alhadlaq
- Molecular Biology Section, Reference Laboratory for Microbiology Department, Research and Laboratories Sector, Saudi Food and Drug Authority, Riyadh 13513, Saudi Arabia
| | - Jumaa Ayubu
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Addisu D. Teklemariam
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
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Deng W, Gibson KE. Microgreen Variety Impacts Leaf Surface Persistence of a Human Norovirus Surrogate. FOOD AND ENVIRONMENTAL VIROLOGY 2023; 15:82-88. [PMID: 36151506 DOI: 10.1007/s12560-022-09536-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
Human norovirus (HuNoV) is a pathogenic agent that is frequently associated with foodborne disease outbreaks linked to fresh produce. Within microgreen production systems, understanding of virus transmission routes and persistence is limited. To investigate virus persistence on microgreen leaf surfaces, this study mimicked virus contaminations caused during microgreen handling by farm workers or during overhead irrigation with contaminated water. Specifically, approximately 5 log PFU of Tulane virus (TV)-a HuNoV surrogate-was inoculated on sunflower (SF) and pea shoot (PS) microgreen leaves at 7-day age. The virus reduction on SF was significantly higher than PS (p < 0.05). On day 10, total TV reduction for SF and PS were 3.70 ± 0.10 and 2.52 ± 0.30 log PFU/plant, respectively. Under the environmental scanning electron microscope (ESEM) observation, the leaf surfaces of SF were visually smoother than PS, while their specific effect on virus persistence were not further characterized. Overall, this study revealed that TV persistence on microgreen leaves was plant variety dependent. In addition, this study provided a preliminary estimation on the risk of HuNoV contamination in a microgreen production system which will aim the future development of prevention and control measures.
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Affiliation(s)
- Wenjun Deng
- Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, 1371 West Altheimer Dr., Fayetteville, AR, 72704, USA
| | - Kristen E Gibson
- Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, 1371 West Altheimer Dr., Fayetteville, AR, 72704, USA.
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Guan H, Sun Y, Hou W, Zhao W, Wang P, Zhao S, Zhao X, Wang D. Infection behavior of Listeria monocytogenes on iceberg lettuce (Lactuca sativa var. capitata). Food Res Int 2023; 165:112487. [PMID: 36869448 DOI: 10.1016/j.foodres.2023.112487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/31/2022] [Accepted: 01/13/2023] [Indexed: 01/19/2023]
Abstract
Iceberg lettuce among leafy vegetables is susceptible to contamination with foodborne pathogens, posing a risk of food microbial safety. Listeria monocytogenes (L. monocytogenes) is a highly lethal pathogen that can survive and proliferate on leafy vegetables. In this paper, the contamination stage, attachment site, internalization pathway, proliferation process, extracellular substance secretion and virulence factors expression of L. monocytogenes on iceberg lettuce were researched. Results showed that the contamination stage of L. monocytogenes on iceberg lettuce was 0-20 min, the proliferation stage was after 20 min. The attachment tissues were stomata and winkles. The internalization distance of L. monocytogenes in the midrib was farther than that in the leaf blade. They enhanced the movement ability of cells by up-regulating the expression of flaA and motA genes, and enhanced the adhesion ability of cells by up-regulating the expression of actA and inla genes, which was beneficial to the proliferation. During proliferation, cells gradually secreted extracellular substances to promote the biofilm formation on iceberg lettuce. The formation of biofilms experienced: individual bacteria, cell aggregation and biofilm maturation. Biofilms were more likely to form on the leaf blade of iceberg lettuce.
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Affiliation(s)
- Hongyang Guan
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China; College of Food Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, China
| | - Yeting Sun
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Wanfu Hou
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Wenting Zhao
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Pan Wang
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Shuang Zhao
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Xiaoyan Zhao
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China
| | - Dan Wang
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing 100097, China.
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15
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Yin HB, Chen CH, Gu G, Nou X, Patel J. Pre-harvest biocontrol of Listeria and Escherichia coli O157 on lettuce and spinach by lactic acid bacteria. Int J Food Microbiol 2023; 387:110051. [PMID: 36516726 DOI: 10.1016/j.ijfoodmicro.2022.110051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022]
Abstract
Recent outbreaks linked to contaminated leafy greens underline the need for identifying effective natural approaches to improve produce safety at pre-harvest level. Lactic acid bacteria (LAB) have been evaluated as biocontrol agents in food products. In this study, the efficacy of a cocktail of LAB including Lactococcus lactis, Lactiplantibacillus plantarum, Lactobacillus johnsonii, and Lactobacillus acidophilus as pre-harvest biocontrol agents against Listeria and Escherichia coli O157 on lettuce and spinach was investigated. Bacterial pathogens L. monocytogenes and E. coli O157:H7 and the non-pathogenic surrogates L. innocua and E. coli O157:H12 were used to spray-inoculate cultivars of lettuce and spinach grown in growth chamber and in field, respectively. Inoculated plants were spray-treated with water or a cocktail of LAB. On day 0, 3, and 5 post-inoculation, four samples from each group were collected and bacterial populations were determined by serial dilution and spiral plating on selective agars. LAB treatment exhibited an immediate antimicrobial efficacy against L. monocytogenes and E. coli O157:H7 on "Green Star" lettuce by ~2 and ~ 1 log reductions under growth chamber conditions, respectively (P < 0.05). The effect of LAB against E. coli O157:H7 on "New Red Fire" lettuce remained effective during the 5-day period in growth chamber (P < 0.05). Treatment of LAB delivered an effective bactericidal effect against E. coli O157:H12 immediately after application on the field-grown lettuce plants (P < 0.05). Approximately 1 log L. innocua reduction was observed on "Matador" and "Palco" spinach on day 5 (P < 0.05). Results of this study support that LAB could potentially be applied as biocontrol agents for controlling Listeria and E. coli O157 contamination on leafy greens at the pre-harvest level.
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Affiliation(s)
- Hsin-Bai Yin
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Chi-Hung Chen
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Ganyu Gu
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Xiangwu Nou
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Jitendra Patel
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA.
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16
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Deblais L, Ranjit S, Vrisman C, Antony L, Scaria J, Miller SA, Rajashekara G. Role of Stress-Induced Proteins RpoS and YicC in the Persistence of Salmonella enterica subsp. enterica Serotype Typhimurium in Tomato Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:109-118. [PMID: 36394339 DOI: 10.1094/mpmi-07-22-0152-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Understanding the functional role of bacterial genes in the persistence of Salmonella in plant organs can facilitate the development of agricultural practices to mitigate food safety risks associated with the consumption of fresh produce contaminated with Salmonella spp. Our study showed that Salmonella enterica subsp. enterica serotype Typhimurium (strain MDD14) persisted less in inoculated tomato plants than other Salmonella Typhimurium strains tested (JSG210, JSG626, JSG634, JSG637, JSG3444, and EV030415; P < 0.01). In-vitro assays performed in limited-nutrient conditions (growth rate, biofilm production, and motility) were inconclusive in explaining the in-planta phenotype observed with MDD14. Whole-genome sequencing combined with non-synonymous single nucleotide variations analysis was performed to identify genomic differences between MDD14 and the other Salmonella Typhimurium strains. The genome of MDD14 contained a truncated version (123 bp N-terminal) of yicC and a mutated version of rpoS (two non-synonymous substitutions, i.e., G66E and R82C), which are two stress-induced proteins involved in iron acquisition, environmental sensing, and cell envelope integrity. The rpoS and yicC genes were deleted in Salmonella Typhimurium JSG210 with the Lambda Red recombining system. Both mutants had limited persistence in tomato plant organs, similar to that of MDD14. In conclusion, we demonstrated that YicC and RpoS are involved in the persistence of Salmonella in tomato plants in greenhouse conditions and, thus, could represent potential targets to mitigate persistence of Salmonella spp. in planta. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Loïc Deblais
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
| | - Sochina Ranjit
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
| | - Claudio Vrisman
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Linto Antony
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, U.S.A
| | - Joy Scaria
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, U.S.A
| | - Sally A Miller
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Gireesh Rajashekara
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
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17
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Wang S, Wang Y, Zhao J, Dong Z, Li J, Nazar M, Kaka NA, Shao T. Influences of growth stage and ensiling time on fermentation profile, bacterial community compositions and their predicted functionality during ensiling of Italian ryegrass. Anim Feed Sci Technol 2023. [DOI: 10.1016/j.anifeedsci.2023.115606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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18
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Foliar Roughness and Water Content Impact on Escherichia coli Attachment in Baby Leafy Greens. BIOLOGY 2023; 12:biology12010102. [PMID: 36671794 PMCID: PMC9855646 DOI: 10.3390/biology12010102] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/03/2023] [Accepted: 01/04/2023] [Indexed: 01/12/2023]
Abstract
Understanding the relation between the susceptibility of different leafy greens to human pathogen contamination and leaf traits can contribute to increase the food safety of the fresh vegetable industry. The aim of this research was to evaluate the susceptibility to E. coli ATCC 35218 attachment in 30 accessions of baby leaves, and to identify leaf traits potentially involved in the contamination. The accessions were surface inoculated with a bacterial suspension containing 1 × 107 cells/mL and the attachment was measured 1.5 h after inoculation. Significant differences in attachment were detected between the accessions for p ≤ 0.05. The three most and the three least susceptible accessions were selected and characterized for leaf micro-morphological traits (stomata density and size, surface roughness) and water content. Scanning electron microscopy was used to analyse the stomatal parameters. Roughness was measured by an innovative portable 3D digital microscope. No significant correlation between the attachment of E. coli ATCC 35218 and stomatal parameters was detected, while the attachment was positively correlated with roughness and water content. The E. coli ATCC 35218 population in surface-inoculated leaves was also measured after a UV treatment, which was found to be less effective in reducing bacterial contamination in the rougher leaves. This result suggested that roughness offers UV protection, further highlighting its impact on the microbiological safety of baby leafy greens.
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19
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Zhao J, Yin XJ, Li JF, Wang SR, Dong ZH, Shao T. Effects of developmental stage and store time on the microbial community and fermentation quality of sweet sorghum silage. ITALIAN JOURNAL OF ANIMAL SCIENCE 2022. [DOI: 10.1080/1828051x.2022.2138788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jie Zhao
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Xue-Jing Yin
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Jun-Feng Li
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Si-Ran Wang
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Zhi-Hao Dong
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Tao Shao
- Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
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20
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Zhao X, Sun Y, Ma Y, Xu Y, Guan H, Wang D. Research advances on the contamination of vegetables by Enterohemorrhagic Escherichia coli: pathways, processes and interaction. Crit Rev Food Sci Nutr 2022; 64:4833-4847. [PMID: 36377729 DOI: 10.1080/10408398.2022.2146045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Enterohemorrhagic Escherichia coli is considered one of the primary bacterial pathogens that cause foodborne diseases because it can survive in meat, vegetables and so on. Understanding of the effect of vegetable characteristics on the adhesion and proliferation process of EHEC is necessary to develop control measures. In this review, the amount and methods of adhesion, the internalization pathway and proliferation process of EHEC have been described during the vegetable contamination. Types, cultivars, tissue characteristics, leaf age, and damage degree can affect EHEC adhesion on vegetables. EHEC cells contaminate the root surface of vegetables through soil and further internalize. It can also contaminate the stem scar tissue of vegetables by rain or irrigation water and internalize the vertical axis, as well as the stomata, necrotic lesions and damaged tissues of vegetable leaves. After EHEC adhered to the vegetables, they may further proliferate and form biofilms. Leaf and fruit tissues were more sensitive to biofilm formation, and shedding rate of biofilms on epidermis tissue was faster. Insights into the mechanisms of vegetable contamination by EHEC, including the role of exopolysaccharides and proteins responsible for movement, adhesion and oxidative stress response could reveal the molecular mechanism by which EHEC contaminates vegetables.
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Affiliation(s)
- Xiaoyan Zhao
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Yeting Sun
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Yue Ma
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Yujia Xu
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Hongyang Guan
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing, China
| | - Dan Wang
- Institute of Agri-food Processing and Nutrition, Beijing Academy of Agriculture and Forestry Sciences, Beijing Key Laboratory of Fruits and Vegetables Preservation and Processing, Key Laboratory of Vegetable Postharvest Processing, Ministry of Agriculture and Rural Affairs, Beijing, China
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21
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Culliney P, Schmalenberger A. Cultivation Conditions of Spinach and Rocket Influence Epiphytic Growth of Listeria monocytogenes. Foods 2022; 11:foods11193056. [PMID: 36230132 PMCID: PMC9563967 DOI: 10.3390/foods11193056] [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: 09/01/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 11/18/2022] Open
Abstract
Leafy vegetables are associated with Listeriosis outbreaks due to contamination with Listeria monocytogenes. To date, contradictory findings were reported on spinach, rocket, and kale, where some studies reported growth of L. monocytogenes, while others did not. Thus, the current study investigated the reason for conflicting findings by producing leafy vegetables, where cultivation factors were known for growth potential studies. Of all polytunnel produce, kale Nero di Toscana demonstrated the highest growth potential (2.56 log cfu g−1), followed by spinach F1 Cello (1.84 log cfu g−1), rocket Buzz (1.41 log cfu g−1), spinach F1 Trumpet (1.37 log cfu g−1), and finally rocket Esmee (1.23 log cfu g−1). Thus, plant species and variety influenced L. monocytogenes growth potentials. Moreover, significantly lower growth potentials of 0.3 log cfu g−1 were identified when rocket Buzz was cultivated in open fields (1.11 log cfu g−1) instead of a polytunnel. The opposite effect was observed for spinach F1 Trumpet, where growth potentials increased significantly by 0.84 log cfu g−1 when cultivated in open fields (2.21 log cfu g−1). Furthermore, a significant seasonality effect between batches was found (p < 0.05). This study revealed that spinach and rocket cultivation conditions are at least co-factors in the reporting of differing growth potentials of L. monocytogenes across literature and should be considered when conducting future growth potential studies.
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22
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Lenzi A, Baldi A, Lombardelli L, Truschi S, Marvasi M, Bruschi P. Contamination of microalgae by Salmonella enterica and Escherichia coli is influenced by selection breeding in chicory ( Cichorium intybus L.). FOOD QUALITY AND SAFETY 2022. [DOI: 10.1093/fqsafe/fyac030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Objectives
The aim of this study was to assess whether selection breeding in chicory (Cichorium intybus L.) led changes in the susceptibility to Salmonella enterica and Escherichia coli contamination and whether the anatomical traits of the leaves are involved in the possible changes.
Materials and Methods
Five chicory genotypes subjected to different intensities of selection were compared at the microgreen stage. Bacterial retention was evaluated after leaf incubation for 1.5 h on the surface of the bacterial suspension, followed by rinsing, grinding, plating on selective media, and CFU counting. The density of stomata and trichomes, total stomatal length and width, stomatal pit width, surface roughness and sharpness were evaluated.
Results
The intensively selected genotype (Witloof) was significantly more prone to contamination ((2.9±0.3) lg CFU/cm 2) as the average of the two bacteril types than the wild accession (Wild) ((2.3±0.4) lg CFU/cm 2) and the moderately selected genotypes (two leaf chicories, Catalogna type, and root chicory ‘Magdeburg’) (on average, (1.9±0.3) lg CFU/cm 2). Witloof microgreens also showed larger stomata (on average + 34% for stoma width and + 44% for pit width), which could justify, at least in part, the higher susceptibility to enterobacteria contamination. In fact, when contamination was performed in the dark (closed stomata), the bacterial retention in Witloof was significantly reduced in comparison with the opened stomata (-44%) and in Wild (-26%). Differences in retention between Witloof and Wild were still observed after UV treatment. The hierarchical clustering performed by grouping the leaf anatomical features was consistent with the chicory genetic groups.
Conclusions
Our results suggest that the domestication process can affect the safety of produce and that the micromorphological traits of the leaves may be involved.
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Affiliation(s)
- Anna Lenzi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Ada Baldi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Letizia Lombardelli
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Stefania Truschi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | | | - Piero Bruschi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
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23
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Yi J, Leveau JH, Nitin N. Role of multiscale leaf surface topography in antimicrobial efficacy of chlorine-based sanitizers. J FOOD ENG 2022. [DOI: 10.1016/j.jfoodeng.2022.111118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Doren J, Hadad R, McKEAG L, Tucker C, Newbold E. Food Safety Risks of Harvesting Dropped and Drooping Produce: A Review. J Food Prot 2022; 85:571-582. [PMID: 34914837 DOI: 10.4315/jfp-21-369] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/10/2021] [Indexed: 11/11/2022]
Abstract
ABSTRACT The Produce Safety Rule of the Food Safety Modernization Act (FSMA) sets forth minimum standards for fruit and vegetable production in the United States. One provision states that growers must not harvest dropped produce because damage or ground contact may contaminate produce. In an unpublished survey of 2020 food safety inspections conducted by the Northeast Center to Advance Food Safety, handling of dropped produce covered by the FSMA was a common misunderstood and noncompliance issue among growers in the Northeast. In consideration of this provision's on-farm practicality, this review was conducted to evaluate the risks associated with dropped and drooping produce, to guide growers in making informed risk management decisions, and to answer the following questions: (i) what are the risk factors that influence transferability of pathogens from touching the ground to produce and (ii) what are the risks associated with harvesting dropped or drooping produce covered under the Produce Safety Rule? A search of online databases revealed 12 relevant publications, which highlighted moisture, contact time, and crop features as affecting contamination rates from a ground surface to a crop surface. Soil and mulch posed a differential risk, with bare soil generally presenting a lower risk than plastic mulch. The effects of other mulch types are unclear. Mulches may promote pathogen persistence in soil, although they may also protect produce from contaminated soils. These studies were limited in their scope and applicability and most did not directly address dropped produce. Research is needed to clarify the various effects of dropped and drooping produce, the impact of ground surface type on pathogen survivability and transfer, soil and crop features that facilitate contamination, and postharvest risks of harvesting dropped or drooping produce. A comprehensive understanding of these issues will guide growers in implementing preventive measures and better managing risk in a way practicable to each farm's unique conditions. HIGHLIGHTS
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Affiliation(s)
- Johanna Doren
- Northeast Center to Advance Food Safety, University of Vermont Extension, Bennington, Vermont 05201
| | - Robert Hadad
- Cornell Vegetable Program, Cornell Cooperative Extension, Rochester, New York 14617
| | - Lisa McKEAG
- Center for Agriculture, Food, and the Environment, University of Massachusetts Extension, Amherst, Massachusetts 01003, USA
| | - Caitlin Tucker
- Cornell Vegetable Program, Cornell Cooperative Extension, Rochester, New York 14617
| | - Elizabeth Newbold
- Northeast Center to Advance Food Safety, University of Vermont Extension, Bennington, Vermont 05201
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25
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Spatial persistence of Escherichia coli O157:H7 flowing on micropatterned structures inspired by stomata and microgrooves of leafy greens. INNOV FOOD SCI EMERG 2022. [DOI: 10.1016/j.ifset.2021.102889] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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26
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Jacob C, Velásquez AC, Josh NA, Settles M, He SY, Melotto M. Dual transcriptomic analysis reveals metabolic changes associated with differential persistence of human pathogenic bacteria in leaves of Arabidopsis and lettuce. G3 (BETHESDA, MD.) 2021; 11:jkab331. [PMID: 34550367 PMCID: PMC8664426 DOI: 10.1093/g3journal/jkab331] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 09/09/2021] [Indexed: 11/14/2022]
Abstract
Understanding the molecular determinants underlying the interaction between the leaf and human pathogenic bacteria is key to provide the foundation to develop science-based strategies to prevent or decrease the pathogen contamination of leafy greens. In this study, we conducted a dual RNA-sequencing analysis to simultaneously define changes in the transcriptomic profiles of the plant and the bacterium when they come in contact. We used an economically relevant vegetable crop, lettuce (Lactuca sativa L. cultivar Salinas), and a model plant, Arabidopsis thaliana Col-0, as well as two pathogenic bacterial strains that cause disease outbreaks associated with fresh produce, Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium 14028s (STm 14028s). We observed commonalities and specificities in the modulation of biological processes between Arabidopsis and lettuce and between O157:H7 and STm 14028s during early stages of the interaction. We detected a larger alteration of gene expression at the whole transcriptome level in lettuce and Arabidopsis at 24 h post inoculation with STm 14028s compared to that with O157:H7. In addition, bacterial transcriptomic adjustments were substantially larger in Arabidopsis than in lettuce. Bacterial transcriptome was affected at a larger extent in the first 4 h compared to the subsequent 20 h after inoculation. Overall, we gained valuable knowledge about the responses and counter-responses of both bacterial pathogen and plant host when these bacteria are residing in the leaf intercellular space. These findings and the public genomic resources generated in this study are valuable for additional data mining.
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Affiliation(s)
- Cristián Jacob
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
- Department of Plant Sciences, Horticulture and Agronomy Graduate Group, University of California, Davis, Davis, CA 95616, USA
- Departamento de Ciencias Vegetales, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile
| | - André C Velásquez
- Department of Biology, Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
| | - Nikhil A Josh
- Bioinformatics Core Facility in the Genome Center, University of California, Davis, Davis, CA 95616, USA
| | - Matthew Settles
- Bioinformatics Core Facility in the Genome Center, University of California, Davis, Davis, CA 95616, USA
| | - Sheng Yang He
- Department of Biology, Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Maeli Melotto
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
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27
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Separating the effects of chemical and microbial factors on fermentation quality and bacterial community of Napier grass silage by using gamma-ray irradiation and epiphytic microbiota transplantation. Anim Feed Sci Technol 2021. [DOI: 10.1016/j.anifeedsci.2021.115082] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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28
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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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29
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Lenzi A, Marvasi M, Baldi A. Agronomic practices to limit pre- and post-harvest contamination and proliferation of human pathogenic Enterobacteriaceae in vegetable produce. Food Control 2021. [DOI: 10.1016/j.foodcont.2020.107486] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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30
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Palma-Salgado S, Ku KM, Dong M, Nguyen TH, Juvik JA, Feng H. Adhesion and removal of E. coli K12 as affected by leafy green produce epicuticular wax composition, surface roughness, produce and bacterial surface hydrophobicity, and sanitizers. Int J Food Microbiol 2020; 334:108834. [PMID: 32861985 DOI: 10.1016/j.ijfoodmicro.2020.108834] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/15/2020] [Accepted: 08/17/2020] [Indexed: 11/29/2022]
Abstract
Contaminated leafy vegetables have been associated with high-profile outbreaks causing severe illnesses. A good understanding of the interactions between human pathogen and produce is important for developing improved food safety control strategies. Currently, the role played by produce surface physiochemical characteristics in such interactions is not well-understood. This work was performed to examine the effects of produce physiochemical characteristics, including surface roughness, epicuticular wax composition, and produce and bacteria surface hydrophobicity on attachment and removal of vegetative bacteria. Escherichia coli K12 was used as a model microorganism to evaluate attachment to and removal from five leafy green vegetables after washing with selected sanitizers. A detailed epicuticular wax component analysis was conducted and the changes of wax composition after sanitation were also evaluated. The results showed that E. coli K12 removal is positively correlated with alkanes, ketones, and total wax content on leaf surfaces. Vegetables with high surface wax content had less rough leaf surfaces and more bacterial removal than the low wax produce. Produce surface roughness positively correlated to E. coli K12 adhesion and negatively correlated to removal. The cells preferentially attached to cut vegetable surfaces, with up to 1.49 times more attachment than on leaf adaxial surfaces.
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Affiliation(s)
- Sindy Palma-Salgado
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Kang-Mo Ku
- Department of Crop Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America; Department of Horticulture, Chonnam National University, Gwangju, South Korea
| | - Mengyi Dong
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Thanh H Nguyen
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - John A Juvik
- Department of Crop Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Hao Feng
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States of America.
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31
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Litt PK, Kakani R, Jadeja R, Saha J, Kountoupis T, Jaroni D. Effectiveness of Bacteriophages Against Biofilm-Forming Shiga-Toxigenic Escherichia coli on Leafy Greens and Cucumbers. PHAGE (NEW ROCHELLE, N.Y.) 2020; 1:213-222. [PMID: 36147291 PMCID: PMC9041472 DOI: 10.1089/phage.2020.0024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Background: Shiga-toxigenic Escherichia coli (STEC) have caused several produce-associated outbreaks, making it challenging to control these pathogens. Bacteriophages could serve as effective biocontrol. Materials and Methods: Spinach, lettuce, and cucumbers, inoculated with STEC (O157, O26, O45, O103, O111, O121, O145), were treated with lytic bacteriophages and stored at 4°C for 3 days. Surviving STEC were enumerated and observed under scanning electron microscope (SEM), and data analyzed using one-way analysis of variance (ANOVA) (p < 0.05). Results: Bacteriophage treatments significantly reduced STEC populations, compared with the control (p < 0.05). On spinach and romaine, STEC O26, O45, and O103 were reduced to undetectable levels and STEC O157, O111, O121, and O145 by ∼2 logs CFU/cm2. Multiserotype phage cocktail reduced STEC on leafy greens by 1.4 CFU/cm2 and on cucumbers by 1.7 logs CFU/cucumber. Clusters of STEC cells, surrounded by extracellular matrix, were observed under SEM of positive control, whereas phage-treated produce surface showed fewer cells, with cellular damage. Conclusions: Bacteriophages could be utilized as biocontrol against STEC on fresh produce.
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Affiliation(s)
- Pushpinder K. Litt
- Department of Animal and Food Sciences, Food and Agricultural Products Center, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Radhika Kakani
- Department of Animal and Food Sciences, Food and Agricultural Products Center, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Ravirajsinh Jadeja
- Department of Animal and Food Sciences, Food and Agricultural Products Center, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Joyjit Saha
- Department of Animal and Food Sciences, Food and Agricultural Products Center, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Tony Kountoupis
- Department of Animal and Food Sciences, Food and Agricultural Products Center, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Divya Jaroni
- Department of Animal and Food Sciences, Food and Agricultural Products Center, Oklahoma State University, Stillwater, Oklahoma, USA
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32
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Kumar GD, Patel J, Ravishankar S. Contamination of spinach at germination: A route to persistence and environmental reintroduction by Salmonella. Int J Food Microbiol 2020; 326:108646. [PMID: 32413802 DOI: 10.1016/j.ijfoodmicro.2020.108646] [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: 12/20/2019] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 11/25/2022]
Abstract
The effects of using contaminated seed and water on the persistence and internalization of Salmonella Newport in organic spinach cultivars- Lazio, Space, Emilia and Waitiki were studied. Seeds were contaminated by either immersing in a suspension of Salmonella and then sprouted or were sprouted in Salmonella contaminated water in the dark at 25 °C. After 5 days, germinated sprouts were analyzed for S. Newport population and internalization. Germinated sprouts were potted in soil and grown in a plant incubator for 4 weeks. Leaves, stems and roots were sampled for Salmonella population by plating on CHROMagar™. Plants surface-sterilized with chlorine were analyzed for internalized pathogen. Potting soil and water runoff were sampled for Salmonella after 4 weeks of plant growth. Contaminated seeds and irrigation water had S. Newport populations of 7.64±0.43 log CFU/g and 7.12±0.04 log CFU/ml, respectively. Sprouts germinated using contaminated water or seeds had S. Newport populations of 8.09±0.04 and 8.08±0.03 log CFU/g, respectively and had a Salmonella population that was significantly higher than other spinach tissues (P<0.05). Populations of S. Newport in leaves, stem and roots of spinach plants were as follows: contaminated seed- 2.82±1.69, 1.69±0.86, and 4.41±0.62 log CFU/ml; contaminated water- 3.56±0.90, 3.04±0.31, and 4.03±0.42 log CFU/ml of macerated tissue suspension, respectively. Internalization was observed in plants developing from contaminated seeds and in sprouts germinated using contaminated water. S. Newport populations of 2.82±0.70 log CFU/g and 1.76±0.46 log CFU/ml were recovered from soil and water runoff, respectively. The results indicate that contamination of spinach during germination can result in persistence, internalization and environmental reintroduction of Salmonella.
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Affiliation(s)
- Govindaraj Dev Kumar
- Center for Food Safety, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, GA 30223, United States of America
| | - Jitendra Patel
- USDA-ARS Environmental Microbial and Food Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD 20705, United States of America
| | - Sadhana Ravishankar
- School of Animal and Comparative Biomedical Sciences, University of Arizona, 1117 E. Lowell Street, Tucson, AZ 85721, United States of America.
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33
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Yin H, Chen C, Karanth S, Byun S, Mayer C, Harriger D, Pradhan A, Patel J. Effect of cultivars and irrigation waters on persistence of indicator bacteria on lettuce grown in high tunnel. J Food Saf 2020. [DOI: 10.1111/jfs.12795] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Hsin‐Bai Yin
- Environmental Microbial and Food Safety LaboratoryUSDA ARS, BARC Beltsville Maryland USA
| | - Chi‐Hung Chen
- Environmental Microbial and Food Safety LaboratoryUSDA ARS, BARC Beltsville Maryland USA
| | - Shraddha Karanth
- Department of Food Science and NutritionUniversity of Maryland College Park Maryland USA
| | - Suyeun Byun
- Environmental Microbial and Food Safety LaboratoryUSDA ARS, BARC Beltsville Maryland USA
| | | | | | - Abani Pradhan
- Department of Food Science and NutritionUniversity of Maryland College Park Maryland USA
| | - Jitendra Patel
- Environmental Microbial and Food Safety LaboratoryUSDA ARS, BARC Beltsville Maryland USA
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34
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Doan HK, Antequera-Gómez ML, Parikh AN, Leveau JHJ. Leaf Surface Topography Contributes to the Ability of Escherichia coli on Leafy Greens to Resist Removal by Washing, Escape Disinfection With Chlorine, and Disperse Through Splash. Front Microbiol 2020; 11:1485. [PMID: 32765440 PMCID: PMC7380079 DOI: 10.3389/fmicb.2020.01485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 06/08/2020] [Indexed: 12/25/2022] Open
Abstract
The attachment of foodborne pathogens to leaf surfaces is a complex process that involves multiple physical, chemical, and biological factors. Here, we report the results from a study designed to specifically determine the contribution of spinach leaf surface topography as it relates to leaf axis (abaxial and adaxial) and leaf age (15, 45, and 75 days old) to the ability of Escherichia coli to resist removal by surface wash, to avoid inactivation by chlorine, and to disperse through splash impact. We used fresh spinach leaves, as well as so-called "replicasts" of spinach leaf surfaces in the elastomer polydimethylsiloxane to show that leaf vein density correlated positively with the failure to recover E. coli from surfaces, not only using a simple water wash and rinse, but also a more stringent wash protocol involving a detergent. Such failure was more pronounced when E. coli was surface-incubated at 24°C compared to 4°C, and in the presence, rather than absence, of nutrients. Leaf venation also contributed to the ability of E. coli to survive a 50 ppm available chlorine wash and to laterally disperse by splash impact. Our findings suggest that the topographical properties of the leafy green surface, which vary by leaf age and axis, may need to be taken into consideration when developing prevention or intervention strategies to enhance the microbial safety of leafy greens.
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Affiliation(s)
- Hung K. Doan
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - María L. Antequera-Gómez
- Departamento de Microbiología, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Universidad de Málaga, Málaga, Spain
| | - Atul N. Parikh
- Department of Biomedical Engineering, University of California, Davis, Davis, CA, United States
- Department of Materials Science and Engineering, University of California, Davis, Davis, CA, United States
| | - Johan H. J. Leveau
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
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35
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Moyne AL, Blessington T, Williams TR, Koike ST, Cahn MD, Marco ML, Harris LJ. Conditions at the time of inoculation influence survival of attenuated Escherichia coli O157:H7 on field-inoculated lettuce. Food Microbiol 2020; 85:103274. [PMID: 31500714 DOI: 10.1016/j.fm.2019.103274] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 10/26/2022]
Abstract
The impact of plant development, environmental conditions at the time of inoculation, and inoculum concentration on survival of attenuated BSL1 Escherichia coli O157:H7 strain ATCC 700728 on field-grown romaine lettuce was evaluated over 3 years. E. coli 700728 was inoculated onto 4- and 6-week-old romaine lettuce plants in the Salinas Valley, CA, at night or the next morning with either low (5 log) or high (7 log) cell numbers per plant to simulate a single aqueous contamination event. At night, when leaf wetness and humidity levels were high, E. coli cell numbers declined by 0.5 log CFU/plant over the first 8-10 h. When applied in the morning, E. coli populations declined up to 2 log CFU/plant within 2 h. However, similar numbers of E. coli were retrieved from lettuce plants at 2 and 7 days. E. coli cell numbers per plant were significantly lower (P < 0.05) 7 days after application onto 4-week-old compared to 6-week-old plants. E. coli 700728 could be recovered by plating or enrichment from a greater proportion of plants for longer times when inoculated at high compared with low initial concentrations and after inoculation of 6-week-old plants compared with 4-week-old plants, even at the low initial inoculum. A contamination event near harvest or when leaf wetness and humidity levels are high may enhance survivability, even when low numbers of E. coli are introduced.
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Affiliation(s)
- Anne-Laure Moyne
- Department of Food Science and Technology, One Shields Avenue, University of California, Davis, CA, 95616-5270, USA; Western Center for Food Safety, University of California, Davis, 1477 Drew Ave., Suite 101, Davis, CA, 95618, USA.
| | - Tyann Blessington
- Department of Food Science and Technology, One Shields Avenue, University of California, Davis, CA, 95616-5270, USA; Western Center for Food Safety, University of California, Davis, 1477 Drew Ave., Suite 101, Davis, CA, 95618, USA.
| | - Thomas R Williams
- Department of Food Science and Technology, One Shields Avenue, University of California, Davis, CA, 95616-5270, USA.
| | - Steven T Koike
- University of California Cooperative Extension, 1432 Abbott Street, Salinas, CA, 93901, USA.
| | - Michael D Cahn
- University of California Cooperative Extension, 1432 Abbott Street, Salinas, CA, 93901, USA.
| | - Maria L Marco
- Department of Food Science and Technology, One Shields Avenue, University of California, Davis, CA, 95616-5270, USA.
| | - Linda J Harris
- Department of Food Science and Technology, One Shields Avenue, University of California, Davis, CA, 95616-5270, USA; Western Center for Food Safety, University of California, Davis, 1477 Drew Ave., Suite 101, Davis, CA, 95618, USA.
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36
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Jacob C, Melotto M. Human Pathogen Colonization of Lettuce Dependent Upon Plant Genotype and Defense Response Activation. FRONTIERS IN PLANT SCIENCE 2020; 10:1769. [PMID: 32082340 PMCID: PMC7002439 DOI: 10.3389/fpls.2019.01769] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/18/2019] [Indexed: 05/26/2023]
Abstract
Fresh produce contaminated with human pathogens may result in foodborne disease outbreaks that cause a significant number of illnesses, hospitalizations, and death episodes affecting both public health and the agribusiness every year. The ability of these pathogens to survive throughout the food production chain is remarkable. Using a genetic approach, we observed that leaf colonization by Salmonella enterica serovar Typhimurium 14028s (S. Typhimurium 14028s) and Escherichia coli O157:H7 was significantly affected by genetic diversity of lettuce (Lactuca sativa L. and L. serriola L.). In particular, there was a significant variation among 11 lettuce genotypes in bacterial attachment, internalization, and apoplastic persistence after surface- and syringe-inoculation methods. We observed a significant correlation of the bacterial leaf internalization rate with stomatal pore traits (width and area). Moreover, bacterial apoplastic populations significantly decreased in 9 out of 11 lettuce genotypes after 10 days of surface inoculation. However, after syringe infiltration, populations of E. coli O157:H7 and S. Typhimurium 14028s showed positive, neutral, or negative net growth in a 10-day experimental period among seedlings of different lettuce types. The relative ability of the bacteria to persist in the apoplast of lettuce genotypes after syringe inoculation was minimally altered when assessed during a longer period (20 days) using 3.5- to 4-week-old plants. Interestingly, contrasting bacterial persistence in the lettuce genotypes Red Tide and Lollo Rossa was positively correlated with significant differences in the level of reactive oxygen species burst and callose deposition against S. Typhimurium 14028s and E. coli O157:H7 which are related to plant defense responses. Overall, we characterized the genetic diversity in the interaction between lettuce genotypes and enterobacteria S. Typhimurium 14028s and E. coli O157:H7 and discovered that this genetic diversity is linked to variations in plant immune responses towards these bacteria. These results provide opportunities to capitalize on plant genetics to reduce pathogen contamination of leaves.
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Affiliation(s)
- Cristián Jacob
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Horticulture and Agronomy Graduate Group, University of California, Davis, Davis, CA, United States
| | - Maeli Melotto
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
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Melotto M, Brandl MT, Jacob C, Jay-Russell MT, Micallef SA, Warburton ML, Van Deynze A. Breeding Crops for Enhanced Food Safety. FRONTIERS IN PLANT SCIENCE 2020; 11:428. [PMID: 32351531 PMCID: PMC7176021 DOI: 10.3389/fpls.2020.00428] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/24/2020] [Indexed: 05/12/2023]
Abstract
An increasing global population demands a continuous supply of nutritious and safe food. Edible products can be contaminated with biological (e.g., bacteria, virus, protozoa), chemical (e.g., heavy metals, mycotoxins), and physical hazards during production, storage, transport, processing, and/or meal preparation. The substantial impact of foodborne disease outbreaks on public health and the economy has led to multidisciplinary research aimed to understand the biology underlying the different contamination processes and how to mitigate food hazards. Here we review the knowledge, opportunities, and challenges of plant breeding as a tool to enhance the food safety of plant-based food products. First, we discuss the significant effect of plant genotypic and phenotypic variation in the contamination of plants by heavy metals, mycotoxin-producing fungi, and human pathogenic bacteria. In addition, we discuss the various factors (i.e., temperature, relative humidity, soil, microbiota, cultural practices, and plant developmental stage) that can influence the interaction between plant genetic diversity and contaminant. This exposes the necessity of a multidisciplinary approach to understand plant genotype × environment × microbe × management interactions. Moreover, we show that the numerous possibilities of crop/hazard combinations make the definition and identification of high-risk pairs, such as Salmonella-tomato and Escherichia coli-lettuce, imperative for breeding programs geared toward improving microbial safety of produce. Finally, we discuss research on developing effective assays and approaches for selecting desirable breeding germplasm. Overall, it is recognized that although breeding programs for some human pathogen/toxin systems are ongoing (e.g., Fusarium in wheat), it would be premature to start breeding when targets and testing systems are not well defined. Nevertheless, current research is paving the way toward this goal and this review highlights advances in the field and critical points for the success of this initiative that were discussed during the Breeding Crops for Enhanced Food Safety workshop held 5-6 June 2019 at University of California, Davis.
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Affiliation(s)
- Maeli Melotto
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- *Correspondence: Maeli Melotto,
| | - Maria T. Brandl
- United States Department of Agriculture-Agricultural Research Service, Produce Safety and Microbiology Research, Albany, CA, United States
| | - Cristián Jacob
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Michele T. Jay-Russell
- Western Center for Food Safety, University of California, Davis, Davis, CA, United States
| | - Shirley A. Micallef
- Department of Plant Science and Landscape Architecture, Center for Food Safety and Security Systems, University of Maryland, College Park, MD, United States
| | - Marilyn L. Warburton
- United States Department of Agriculture-Agricultural Research Service, Corn Host Plant Research Resistance Unit Mississippi State, Starkville, MS, United States
| | - Allen Van Deynze
- Plant Breeding Center, Department of Plant Sciences, University of California, Davis, Davis, CA, United States
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38
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Elucidating Escherichia Coli O157:H7 Colonization and Internalization in Cucumbers Using an Inverted Fluorescence Microscope and Hyperspectral Microscopy. Microorganisms 2019; 7:microorganisms7110499. [PMID: 31661860 PMCID: PMC6920880 DOI: 10.3390/microorganisms7110499] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/17/2019] [Accepted: 10/17/2019] [Indexed: 11/18/2022] Open
Abstract
Contamination of fresh cucumbers (Cucumis sativus L.) with Escherichia coli O157:H7 can impact the health of consumers. Despite this, the pertinent mechanisms underlying E. coli O157:H7 colonization and internalization remain poorly documented. Herein we aimed to elucidate these mechanisms in cucumbers using an inverted fluorescence microscope and hyperspectral microscopy. We observed that E. coli O157:H7 primarily colonized around the stomata on cucumber epidermis without invading the internal tissues of intact cucumbers. Once the bacterial cells had infiltrated into the internal tissues, they colonized the cucumber placenta and vascular bundles (xylem vessels, in particular), and also migrated along the xylem vessels. Moreover, the movement rate of E. coli O157:H7 from the stalk to the flower bud was faster than that from the flower bud to the stalk. We then used hyperspectral microscope imaging to categorize the infiltrated and uninfiltrated areas with high accuracy using the spectral angle mapper (SAM) classification method, which confirmed the results obtained upon using the inverted fluorescence microscope. We believe that our results are pivotal for developing science-based food safety practices, interventions for controlling E. coli O157:H7 internalization, and new methods for detecting E. coli O157:H7-plant interactions.
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39
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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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40
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Erickson MC, Liao JY, Payton AS, Cook PW, Ortega YR. Survival and internalization of Salmonella and Escherichia coli O157:H7 sprayed onto different cabbage cultivars during cultivation in growth chambers. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2019; 99:3530-3537. [PMID: 30624787 DOI: 10.1002/jsfa.9573] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 12/17/2018] [Accepted: 12/23/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Cabbage may become contaminated with enteric pathogens during cultivation. Using multiple cabbage cultivars at two maturity stages (small plants or plants with small heads) in growth chamber studies, the fate (internalization or surface survival) of Salmonella and Escherichia coli O157:H7 (0157) were examined in conjunction with any potential relationships to the plant's antimicrobial content. RESULTS Internalized Salmonella was detected in cabbage within 24 h with prevalence ranging from 62% (16 of 26) for the 'Super Red 80' cultivar to 92% (24 of 26) for the 'Red Dynasty' cultivar. Surface survival of pathogens on small cabbage plants over nine days was significantly affected by cultivar with both pathogens surviving the most on the 'Farao' cultivar and Salmonella and O157 surviving the least on the 'Super Red 80' and 'Capture' cultivars, respectively (P < 0.05). Survival of O157 was slightly higher on cabbage heads for O157 than small plants suggesting that the maturity stage may affect this pathogen's fate. An inverse relationship existed between antimicrobial levels and the pathogen's surface survival on cabbage heads (P < 0.05). CONCLUSIONS The fate of pathogens varied with the cabbage cultivar in growth chamber studies highlighting the potential to explore cultivar in field studies to reduce the risk of microbiological contamination in this crop. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Marilyn C Erickson
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, GA, USA
| | - Jye-Yin Liao
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, GA, USA
| | - Alison S Payton
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, GA, USA
| | - Peter W Cook
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, GA, USA
| | - Ynes R Ortega
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, Griffin, GA, USA
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41
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Effects of organic acid alone and in combination with H2O2 and NaCl on Escherichia coli O157:H7: An evaluation of antioxidant retention and overall acceptability in Basil leaves (Ocimum basilicum). Int J Food Microbiol 2019; 292:56-63. [DOI: 10.1016/j.ijfoodmicro.2018.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 12/04/2018] [Accepted: 12/12/2018] [Indexed: 11/23/2022]
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42
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Xu A, Buchanan RL. Evaluation of sampling methods for the detection of pathogenic bacteria on pre-harvest leafy greens. Food Microbiol 2018; 77:137-145. [PMID: 30297044 DOI: 10.1016/j.fm.2018.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 08/19/2018] [Accepted: 09/05/2018] [Indexed: 10/28/2022]
Abstract
Recent outbreaks of foodborne disease associated with leafy greens have led to increased pre-harvest testing for pathogens and indicator microorganisms. However, the scientific and statistical rationale and the performance attributes for pre-harvest sampling methods are not well understood. The performance of three pre-harvest sampling methods, random, stratified random, and Z-pattern sampling, was evaluated by consideration of their mathematical derivations, computer simulations and field validation. Consideration of the probabilistic basis of the sampling methods indicated that the mean detection rates were similar. However, use of simulation modeling to assess the uncertainty associated with the three sampling methods indicated that the inherent variability of the Z-pattern sampling method was substantially greater than the other two sampling methods. A simulation tool was developed in Matlab that allowed the evaluation of the effectiveness of the three sampling methods. A limited validation study also observed that Z-pattern sampling had higher variability than the other two sampling methods. This study indicates that while the mean detection probabilities for the three sampling methods are similar, the random or stratified random sampling are less variable, particularly when the number of contamination sites or number of samples analyzed are small.
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Affiliation(s)
- Aixia Xu
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, 20742, USA.
| | - Robert L Buchanan
- Department of Nutrition and Food Science, University of Maryland, College Park, MD, 20742, USA; Center for Food Safety and Security Systems, University of Maryland, College Park, MD, 20742, USA.
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43
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Zhou B, Luo Y, Bauchan GR, Feng H, Stommel JR. Visualizing pathogen internalization pathways in fresh tomatoes using MicroCT and confocal laser scanning microscopy. Food Control 2018. [DOI: 10.1016/j.foodcont.2017.09.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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45
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Contribution of cropland to the spread of Shiga toxin phages and the emergence of new Shiga toxin-producing strains. Sci Rep 2017; 7:7796. [PMID: 28798380 PMCID: PMC5552810 DOI: 10.1038/s41598-017-08169-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/07/2017] [Indexed: 11/09/2022] Open
Abstract
A growing interest in healthy eating has lead to an increase in the consumption of vegetables, associated with a rising number of bacterial outbreaks related to fresh produce. This is the case of the outbreak in Germany, caused by a O104:H4 enteroaggregative E. coli strain lysogenic for a Stx phage. Temperate Stx phages released from their hosts occur as free particles in various environments. This study reports the occurrence of Stx phages in vegetables (lettuce, cucumber, and spinach) and cropland soil samples. Infectious Stx2 phages were found in all samples and many carried also Stx1 phages. Their persistence in vegetables, including germinated sprouts, of Stx phage 933 W and an E. coli C600 (933 W∆stx::gfp-cat) lysogen used as surrogate, showed reductions below 2 log10 units of both microorganisms at 23 °C and 4 °C over 10 days. Higher reductions (up to 3.9 log10) units were observed in cropland soils at both temperatures. Transduction of a recombinant 933 W∆stx::kan phage was observed in all matrices. Protecting against microbial contamination of vegetables is imperative to ensure a safe food chain. Since the emergence of new Stx strains by Stx phage transduction is possible in vegetable matrices, methods aimed at reducing microbial risks in vegetables should not neglect phages.
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46
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Chen YI, Burall LS, Macarisin D, Pouillot R, Strain E, DE Jesus AJ, Laasri A, Wang H, Ali L, Tatavarthy A, Zhang G, Hu L, Day J, Kang J, Sahu S, Srinivasan D, Klontz K, Parish M, Evans PS, Brown EW, Hammack TS, Zink DL, Datta AR. Prevalence and Level of Listeria monocytogenes in Ice Cream Linked to a Listeriosis Outbreak in the United States. J Food Prot 2016; 79:1828-1832. [PMID: 28221903 DOI: 10.4315/0362-028x.jfp-16-208] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A most-probable-number (MPN) method was used to enumerate Listeria monocytogenes in 2,320 commercial ice cream scoops manufactured on a production line that was implicated in a 2015 listeriosis outbreak in the United States. The analyzed samples were collected from seven lots produced in November 2014, December 2014, January 2015, and March 2015. L. monocytogenes was detected in 99% (2,307 of 2,320) of the tested samples (lower limit of detection, 0.03 MPN/g), 92% of which were contaminated at <20 MPN/g. The levels of L. monocytogenes in these samples had a geometric mean per lot of 0.15 to 7.1 MPN/g. The prevalence and enumeration data from an unprecedented large number of naturally contaminated ice cream products linked to a listeriosis outbreak provided a unique data set for further understanding the risk associated with L. monocytogenes contamination for highly susceptible populations.
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Affiliation(s)
- Y I Chen
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Laurel S Burall
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Applied Research and Safety Assessment, Laurel, Maryland 20708, USA
| | - Dumitru Macarisin
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Régis Pouillot
- Office of Analytics and Outreach, College Park, Maryland 20740
| | - Errol Strain
- Office of Analytics and Outreach, College Park, Maryland 20740
| | - Antonio J DE Jesus
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Anna Laasri
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Hua Wang
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Laila Ali
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Aparna Tatavarthy
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Guodong Zhang
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Lijun Hu
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - James Day
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Jihun Kang
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Applied Research and Safety Assessment, Laurel, Maryland 20708, USA
| | - Surasri Sahu
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Applied Research and Safety Assessment, Laurel, Maryland 20708, USA
| | - Devayani Srinivasan
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Applied Research and Safety Assessment, Laurel, Maryland 20708, USA
| | - Karl Klontz
- Office of Analytics and Outreach, College Park, Maryland 20740
| | - Mickey Parish
- Office of the Center Director, College Park, Maryland 20740
| | - Peter S Evans
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Eric W Brown
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Thomas S Hammack
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, Maryland 20740
| | - Donald L Zink
- Office of the Center Director, College Park, Maryland 20740
| | - Atin R Datta
- U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Applied Research and Safety Assessment, Laurel, Maryland 20708, USA
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47
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Chen Y, Pouillot R, S Burall L, Strain EA, Van Doren JM, De Jesus AJ, Laasri A, Wang H, Ali L, Tatavarthy A, Zhang G, Hu L, Day J, Sheth I, Kang J, Sahu S, Srinivasan D, Brown EW, Parish M, Zink DL, Datta AR, Hammack TS, Macarisin D. Comparative evaluation of direct plating and most probable number for enumeration of low levels of Listeria monocytogenes in naturally contaminated ice cream products. Int J Food Microbiol 2016; 241:15-22. [PMID: 27741432 DOI: 10.1016/j.ijfoodmicro.2016.09.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 07/11/2016] [Accepted: 09/24/2016] [Indexed: 11/25/2022]
Abstract
A precise and accurate method for enumeration of low level of Listeria monocytogenes in foods is critical to a variety of studies. In this study, paired comparison of most probable number (MPN) and direct plating enumeration of L. monocytogenes was conducted on a total of 1730 outbreak-associated ice cream samples that were naturally contaminated with low level of L. monocytogenes. MPN was performed on all 1730 samples. Direct plating was performed on all samples using the RAPID'L.mono (RLM) agar (1600 samples) and agar Listeria Ottaviani and Agosti (ALOA; 130 samples). Probabilistic analysis with Bayesian inference model was used to compare paired direct plating and MPN estimates of L. monocytogenes in ice cream samples because assumptions implicit in ordinary least squares (OLS) linear regression analyses were not met for such a comparison. The probabilistic analysis revealed good agreement between the MPN and direct plating estimates, and this agreement showed that the MPN schemes and direct plating schemes using ALOA or RLM evaluated in the present study were suitable for enumerating low levels of L. monocytogenes in these ice cream samples. The statistical analysis further revealed that OLS linear regression analyses of direct plating and MPN data did introduce bias that incorrectly characterized systematic differences between estimates from the two methods.
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Affiliation(s)
- Yi Chen
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA.
| | - Régis Pouillot
- Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Laurel S Burall
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, Food and Drug Administration, Laurel, MD 20708, USA
| | - Errol A Strain
- Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Jane M Van Doren
- Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Antonio J De Jesus
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Anna Laasri
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Hua Wang
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Laila Ali
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Aparna Tatavarthy
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Guodong Zhang
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Lijun Hu
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - James Day
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Ishani Sheth
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Jihun Kang
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, Food and Drug Administration, Laurel, MD 20708, USA
| | - Surasri Sahu
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, Food and Drug Administration, Laurel, MD 20708, USA
| | - Devayani Srinivasan
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, Food and Drug Administration, Laurel, MD 20708, USA
| | - Eric W Brown
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Mickey Parish
- Office of the Center Director, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Donald L Zink
- Office of the Center Director, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Atin R Datta
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, Food and Drug Administration, Laurel, MD 20708, USA
| | - Thomas S Hammack
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Dumitru Macarisin
- Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
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48
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Carter MQ, Louie JW, Feng D, Zhong W, Brandl MT. Curli fimbriae are conditionally required in Escherichia coli O157:H7 for initial attachment and biofilm formation. Food Microbiol 2016; 57:81-9. [DOI: 10.1016/j.fm.2016.01.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 12/21/2015] [Accepted: 01/21/2016] [Indexed: 01/10/2023]
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49
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De Keuckelaere A, Jacxsens L, Amoah P, Medema G, McClure P, Jaykus LA, Uyttendaele M. Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce. Compr Rev Food Sci Food Saf 2015. [DOI: 10.1111/1541-4337.12140] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Ann De Keuckelaere
- Dept. of Food Safety & Food Quality; Faculty of Bio-Science Engineering; Ghent Univ; Belgium
| | - Liesbeth Jacxsens
- Dept. of Food Safety & Food Quality; Faculty of Bio-Science Engineering; Ghent Univ; Belgium
| | - Philip Amoah
- Intl. Water Management Inst. (IWMI); Accra Ghana
| | - Gertjan Medema
- Water Quality & Health, KWR Watercycle Research Inst. and Water Management, Faculty of Civil Engineering & Geosciences; Delft Univ. of Technology; the Netherlands
| | | | | | - Mieke Uyttendaele
- Dept. of Food Safety & Food Quality; Faculty of Bio-Science Engineering; Ghent Univ; Belgium
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50
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Role of Extracellular Structures of Escherichia coli O157:H7 in Initial Attachment to Biotic and Abiotic Surfaces. Appl Environ Microbiol 2015; 81:4720-7. [PMID: 25956766 DOI: 10.1128/aem.00215-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 04/27/2015] [Indexed: 11/20/2022] Open
Abstract
Infection by human pathogens through the consumption of fresh, minimally processed produce and solid plant-derived foods is a major concern of the U.S. and global food industries and of public health services. Enterohemorrhagic Escherichia coli O157:H7 is a frequent and potent foodborne pathogen that causes severe disease in humans. Biofilms formed by E. coli O157:H7 facilitate cross-contamination by sheltering pathogens and protecting them from cleaning and sanitation operations. The objective of this research was to determine the role that several surface structures of E. coli O157:H7 play in adherence to biotic and abiotic surfaces. A set of isogenic deletion mutants lacking major surface structures was generated. The mutant strains were inoculated onto fresh spinach and glass surfaces, and their capability to adhere was assessed by adherence assays and fluorescence microscopy methods. Our results showed that filament-deficient mutants bound to the spinach leaves and glass surfaces less strongly than the wild-type strain did. We mimicked the switch to the external environment-during which bacteria leave the host organism and adapt to lower ambient temperatures of cultivation or food processing-by decreasing the temperature from 37°C to 25°C and 4°C. We concluded that flagella and some other cell surface proteins are important factors in the process of initial attachment and in the establishment of biofilms. A better understanding of the specific roles of these structures in early stages of biofilm formation can help to prevent cross-contaminations and foodborne disease outbreaks.
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