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Henriquez T, Guerra S, Nerini M, Purchase D, Marvasi M. The Tomato Variety Affects the Survival of Shigella flexneri 2a in Fruit Pericarp. Pathogens 2024; 13:379. [PMID: 38787231 PMCID: PMC11124042 DOI: 10.3390/pathogens13050379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 04/08/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024] Open
Abstract
The presence of enteric pathogens in produce can serve as a significant means of transmitting infections to consumers. Notably, tomatoes, as a type of produce, have been implicated in outbreaks caused by various human pathogens, such as Salmonella enterica and pathogenic Escherichia coli. However, the survival characteristics of Shigella spp. in tomatoes have not been thoroughly investigated. In this study, we assess the survival of S. flexneri 2a in two distinct varieties of post-harvested tomatoes. S. flexneri 2a was used to inoculate both regular-sized Vine tomatoes and cherry-type Mini Plum tomatoes. Our findings reveal no significant difference in Shigella survival in the pericarp of both varieties on day 2 post-inoculation. However, a significant disparity emerges on day 6, where all recovered Shigella colonies exclusively belong to the Mini Plum variety, with none associated with the Vine type. When Shigella was inoculated into the locular cavity (deep inoculation), no significant difference between varieties was observed. Additionally, we investigate the potential role of the SRL pathogenicity island (SRL PAI) in the survival and fitness of S. flexneri 2a in post-harvested tomatoes. Our results indicate that while the SRL PAI is not linked to the survival of the strains in tomato, it does impact their fitness. These findings underscore the variability in Shigella strains' survival capabilities depending on the tomato variety, highlighting the importance of understanding Shigella ecology beyond the human host and identifying molecular determinants influencing bacterial survival to mitigate the risk of future outbreaks. The significance of this data on Shigella persistence in fresh vegetables should not be underestimated, as even a small number of Shigella cells can pose a threat to the health of individuals.
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Affiliation(s)
- Tania Henriquez
- Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy;
| | - Simona Guerra
- Department of Biology, University of Florence, 50019 Florence, Italy; (S.G.); (M.N.)
| | - Marta Nerini
- Department of Biology, University of Florence, 50019 Florence, Italy; (S.G.); (M.N.)
| | - Diane Purchase
- Department of Natural Sciences, Middlesex University London, London NW4 4BT, UK;
| | - Massimiliano Marvasi
- Department of Biology, University of Florence, 50019 Florence, Italy; (S.G.); (M.N.)
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2
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Szymańska S, Deja-Sikora E, Sikora M, Niedojadło K, Mazur J, Hrynkiewicz K. Colonization of Raphanus sativus by human pathogenic microorganisms. Front Microbiol 2024; 15:1296372. [PMID: 38426059 PMCID: PMC10902717 DOI: 10.3389/fmicb.2024.1296372] [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: 09/18/2023] [Accepted: 01/15/2024] [Indexed: 03/02/2024] Open
Abstract
Contamination of vegetables with human pathogenic microorganisms (HPMOs) is considered one of the most important problems in the food industry, as current nutritional guidelines include increased consumption of raw or minimally processed organic vegetables due to healthy lifestyle promotion. Vegetables are known to be potential vehicles for HPMOs and sources of disease outbreaks. In this study, we tested the susceptibility of radish (Raphanus sativus) to colonization by different HPMOs, including Escherichia coli PCM 2561, Salmonella enterica subsp. enterica PCM 2565, Listeria monocytogenes PCM 2191 and Bacillus cereus PCM 1948. We hypothesized that host plant roots containing bactericidal compounds are less prone to HPMO colonization than shoots and leaves. We also determined the effect of selected pathogens on radish growth to check host plant-microbe interactions. We found that one-week-old radish is susceptible to colonization by selected HPMOs, as the presence of the tested HPMOs was demonstrated in all organs of R. sativus. The differences were noticed 2 weeks after inoculation because B. cereus was most abundant in roots (log10 CFU - 2.54), S. enterica was observed exclusively in stems (log10 CFU - 3.15), and L. monocytogenes and E. coli were most abundant in leaves (log10 CFU - 4.80 and 3.23, respectively). The results suggest that E. coli and L. monocytogenes show a higher ability to colonize and move across the plant than B. cereus and S. enterica. Based on fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) approach HPMOs were detected in extracellular matrix and in some individual cells of all analyzed organs. The presence of pathogens adversely affected the growth parameters of one-week-old R. sativus, especially leaf and stem fresh weight (decreased by 47-66 and 17-57%, respectively). In two-week-old plants, no reduction in plant biomass development was noted. This observation may result from plant adaptation to biotic stress caused by the presence of HPMOs, but confirmation of this assumption is needed. Among the investigated HPMOs, L. monocytogenes turned out to be the pathogen that most intensively colonized the aboveground part of R. sativus and at the same time negatively affected the largest number of radish growth parameters.
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Affiliation(s)
- Sonia Szymańska
- Department of Microbiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
| | - Edyta Deja-Sikora
- Department of Microbiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
| | - Marcin Sikora
- Center for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland
| | - Katarzyna Niedojadło
- Department of Cellular and Molecular Biology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
| | - Justyna Mazur
- Center for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland
| | - Katarzyna Hrynkiewicz
- Department of Microbiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, Toruń, Poland
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3
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Topalcengiz Z, Chandran S, Gibson KE. A comprehensive examination of microbial hazards and risks during indoor soilless leafy green production. Int J Food Microbiol 2024; 411:110546. [PMID: 38157635 DOI: 10.1016/j.ijfoodmicro.2023.110546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/26/2023] [Accepted: 12/16/2023] [Indexed: 01/03/2024]
Abstract
Produce grown under controlled environment agriculture (CEA) is often assumed to have a reduced risk of pathogen contamination due to the low chance of exposure to outdoor contaminant factors. However, the 2021 outbreak and numerous recalls of CEA-grown lettuce and microgreens demonstrate the possibility of pathogen introduction during indoor production when there is a failure in the implementation of food safety management systems. Indoor production of commercial leafy greens, such as lettuce and microgreens, is performed across a range of protective structures from primitive household setups to advanced and partially automatized growing systems. Indoor production systems include hydroponic, aquaponic, and aeroponic configurations. Hydroponic systems such as deep water culture and nutrient film technique comprised of various engineering designs represent the main system types used by growers. Depending on the type of leafy green, the soilless substrate, and system selection, risk of microbial contamination will vary during indoor production. In this literature review, science-based pathogen contamination risks and mitigation strategies for indoor production of microgreens and more mature leafy greens are discussed during both pre-harvest and post-harvest stages of production.
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Affiliation(s)
- Zeynal Topalcengiz
- Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, Fayetteville, AR 72704, USA; Department of Food Engineering, Faculty of Engineering and Architecture, Muş Alparslan University, 49250 Muş, Türkiye
| | - Sahaana Chandran
- Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, Fayetteville, AR 72704, USA
| | - Kristen E Gibson
- Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture, Fayetteville, AR 72704, USA.
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4
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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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5
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Han M, Zarkani AA, Duan Y, Grimm M, Trotereau J, Virlogeux-Payant I, Schikora A. Bidirectional Comparisons Revealed Functional Patterns in Interaction between Salmonella enterica and Plants. PLANTS (BASEL, SWITZERLAND) 2024; 13:414. [PMID: 38337947 PMCID: PMC10857149 DOI: 10.3390/plants13030414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/22/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024]
Abstract
Plants may harbor the human pathogen Salmonella enterica. Interactions between S. enterica and different plant species have been studied in individual reports. However, disparities arising from the distinct experimental conditions may render a meaningful comparison very difficult. This study explored interaction patterns between different S. enterica strains including serovars Typhimurium 14028s and LT2 and serovar Senftenberg, and different plants (Arabidopsis, lettuce, and tomato) in one approach. Better persistence of S. enterica serovar Typhimurium strains was observed in all tested plants, whereas the resulting symptoms varied depending on plant species. Genes encoding pathogenesis-related proteins were upregulated in plants inoculated with Salmonella. Furthermore, transcriptome of tomato indicated dynamic responses to Salmonella, with strong and specific responses already 24 h after inoculation. By comparing with publicly accessible Arabidopsis and lettuce transcriptome results generated in a similar manner, constants and variables were displayed. Plants responded to Salmonella with metabolic and physiological adjustments, albeit with variability in reprogrammed orthologues. At the same time, Salmonella adapted to plant leaf-mimicking media with changes in biosynthesis of cellular components and adjusted metabolism. This study provides insights into the Salmonella-plant interaction, allowing for a direct comparison of responses and adaptations in both organisms.
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Affiliation(s)
- Min Han
- Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (M.H.)
- INRAE Val de Loire, Université de Tours, L’Unité Mixte de Recherche Infectiologie et Santé Publique (UMR ISP), 37380 Nouzilly, France
| | - Azhar A. Zarkani
- Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (M.H.)
| | - Yongming Duan
- Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (M.H.)
| | - Maja Grimm
- Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (M.H.)
| | - Jérôme Trotereau
- INRAE Val de Loire, Université de Tours, L’Unité Mixte de Recherche Infectiologie et Santé Publique (UMR ISP), 37380 Nouzilly, France
| | - Isabelle Virlogeux-Payant
- INRAE Val de Loire, Université de Tours, L’Unité Mixte de Recherche Infectiologie et Santé Publique (UMR ISP), 37380 Nouzilly, France
| | - Adam Schikora
- Julius Kühn Institute (JKI)—Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104 Braunschweig, Germany; (M.H.)
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Detert K, Schmidt H. Sporadic Detection of Escherichia coli O104:H4 Strain C227/11Φcu in the Edible Parts of Lamb's Lettuce Cultured in Contaminated Agricultural Soil Samples. Microorganisms 2023; 11:2072. [PMID: 37630632 PMCID: PMC10457958 DOI: 10.3390/microorganisms11082072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/04/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
In the current study, we demonstrate that E. coli O104:H4 strain C227/11Φcu, a derivative of the 2011 enterohemorrhagic/enteroaggregative (EHEC/EAEC) E. coli outbreak strain, migrated into the edible portion of lamb's lettuce plants upon contamination of the surrounding soil. Seeds were surface-sterilized and cultivated on Murashige-Skoog agar or in autoclaved agricultural soil. Migration into the edible portions was investigated by inoculating the agar or soil close to the plants with 108 colony-forming units (CFU). The edible parts, which did not come into contact with the contaminated medium or soil, were quantitatively analyzed for the presence of bacteria after 2, 4 and 8 weeks. Strain C227/11Φcu could colonize lamb's lettuce when contamination of medium or soil occurs. The highest recovery rate (27%) was found for lettuce cultivated in agar, and up to 1.6 × 103 CFU/g lettuce was detected. The recovery rate was lower for the soil samples (9% and 13.5%). Although the used contamination levels were high, migration of C227/11Φcu from the soil into the edible parts was demonstrated. This study further highlights the risk of crop plant contamination with pathogenic E. coli upon soil contamination.
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Affiliation(s)
| | - Herbert Schmidt
- Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 28, 70599 Stuttgart, Germany;
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Guerra S, Michelotti M, Signorini S, Rossi G, Procopio T, Truschi S, Lenzi A, Marvasi M. Pre-heated blades for harvesting baby-leaves reduce the risk of Escherichia coli internalization in leaves. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2023; 103:3621-3627. [PMID: 36377360 DOI: 10.1002/jsfa.12335] [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: 07/21/2022] [Revised: 10/11/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Pathogenic enterobacteria can travel through the plant vascular bundles by penetrating from cuts and persisting into ready-to-eat leafy greens. Because the cutting site is the main point of entrance and uptake, we tested how different cutting strategies can reduce bacterial internalization in leaves. Horizontal cuts at the base of the leaves were performed with two different types of tools: the first with a scalpel (by pulling the blade) and the second with a scissor-action that has blades that cuts by gliding against a thicker blade. Scissor-action generally makes closer border cuts. Blades of both types of tools have worked at 25 °C and 200 °C. The present study aimed to determine how these different types of cuts and temperatures affected bacterial uptake in leaves. Experiments were repeated on different plant genotypes and at different wilting stages. RESULTS Our findings showed that cutting baby-leaves with a scissor action at 200 °C significantly reduced the bacterial uptake compared to the not heated (which simulates a mechanized lettuce harvester). The most effective cutting treatments for reducing bacterial uptake were in the order: scissor 200 °C > scissor 25 °C > scalpel 200 °C > scalpel 25 °C. The scissor heated at 200 °C also prevented bacterial uptake on wilted baby-leaves. CONCLUSION The findings of the present study could provide a further contribution in terms of safety during harvest and suggest that a pre-heated blade supports safety during harvest of leafy greens. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Simona Guerra
- Department of Biology, University of Florence, Florence, Italy
| | | | - Sofia Signorini
- Department of Biology, University of Florence, Florence, Italy
| | - Giuseppe Rossi
- Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Florence, Italy
| | - Tiziana Procopio
- Division Food Safety and Quality Control, Azienda Agricola Cammelli, Florence, Italy
| | - Stefania Truschi
- 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
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Tang M, Wu Z, Li W, Shoaib M, Aqib AI, Shang R, Yang Z, Pu W. Effects of different composting methods on antibiotic-resistant bacteria, antibiotic resistance genes, and microbial diversity in dairy cattle manures. J Dairy Sci 2022; 106:257-273. [DOI: 10.3168/jds.2022-22193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022]
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9
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Karmakar K, Bhattacharya R, Sharma A, Parmar K, Nath U, Nataraja KN, N E, Sharma G, Chakravortty D. Lysinibacillus macroides-mediated control of cellulose-producing morphotype of Salmonella. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:6491-6501. [PMID: 35567417 DOI: 10.1002/jsfa.12016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 05/07/2022] [Accepted: 05/14/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Soil-dwelling human pathogens like Salmonella are transmitted by fresh produce such as tomato, spinach, onion and cabbage. With >2600 serovars, it is difficult to classify the good plant colonizers from the non-colonizers. Generally, soil microbiota are classified as autochthonous or zymogenous organisms, based on their ability to survive in soil. However, such information for soil-dwelling human pathogens is not available Thus there is a need to classify these organisms for designing a strategy to prevent their outbreak. Moreover, soil harbours a plethora of microbes, which can be screened for competitive organisms to control such human pathogens. RESULTS In this study, we examined whether the morphotype based on the attachment factors (e.g., cellulose and curli fimbri) of Salmonella was important for its colonization of roots. Secondly, we tracked the location of the bacteria in the plant cell. Interestingly, most of the epidermal cells occupied by Salmonella showed propidium iodide-positive nuclei. As an extension of the study, a screening of competitive rhizospheric bacteria was performed. One isolate, identified as Lysinibacillus macroides, was able to inhibit the biofilm of Salmonella and subsequently reduced its colonization on roots. CONCLUSION Based on this study, we classified the Rdar (red, dry and rough) morphotypes as good plant colonists. The ability to colonize and subsequent kill the live plant cell throws light on the zymogenous life cycle of soil-dwelling Salmonella. Additionally, Lysinibacillus macroides served as a biocontrol agent by reducing the burden of Salmonella in various vegetables. Such organisms can further be explored to prevent contamination of the food chain. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Kapudeep Karmakar
- Regional Research Station, Terai Zone, Uttar Banga Krishi Viswavidyalaya, Coochbehar, West Bengal, India
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Rohan Bhattacharya
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Abhishek Sharma
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Kirti Parmar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Utpal Nath
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Karaba N Nataraja
- Department of Crop Physiology, University of Agricultural Science, Bangalore, Karnataka, India
| | - Earanna N
- Department of Agricultural Microbiology, University of Agricultural Science, Bangalore, Karnataka, India
| | - Gaurav Sharma
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
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Riva V, Patania G, Riva F, Vergani L, Crotti E, Mapelli F. Acinetobacter baylyi Strain BD413 Can Acquire an Antibiotic Resistance Gene by Natural Transformation on Lettuce Phylloplane and Enter the Endosphere. Antibiotics (Basel) 2022; 11:antibiotics11091231. [PMID: 36140010 PMCID: PMC9495178 DOI: 10.3390/antibiotics11091231] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/03/2022] [Accepted: 09/06/2022] [Indexed: 12/03/2022] Open
Abstract
Antibiotic resistance spread must be considered in a holistic framework which comprises the agri-food ecosystems, where plants can be considered a bridge connecting water and soil habitats with the human microbiome. However, the study of horizontal gene transfer events within the plant microbiome is still overlooked. Here, the environmental strain Acinetobacter baylyi BD413 was used to study the acquisition of extracellular DNA (exDNA) carrying an antibiotic resistance gene (ARG) on lettuce phylloplane, performing experiments at conditions (i.e., plasmid quantities) mimicking those that can be found in a water reuse scenario. Moreover, we assessed how the presence of a surfactant, a co-formulant widely used in agriculture, affected exDNA entry in bacteria and plant tissues, besides the penetration and survival of bacteria into the leaf endosphere. Natural transformation frequency in planta was comparable to that occurring under optimal conditions (i.e., temperature, nutrient provision, and absence of microbial competitors), representing an entrance pathway of ARGs into an epiphytic bacterium able to penetrate the endosphere of a leafy vegetable. The presence of the surfactant determined a higher presence of culturable transformant cells in the leaf tissues but did not significantly increase exDNA entry in A. baylyi BD413 cells and lettuce leaves. More research on HGT (Horizontal Gene Transfer) mechanisms in planta should be performed to obtain experimental data on produce safety in terms of antibiotic resistance.
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11
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Grivokostopoulos NC, Makariti IP, Tsadaris S, Skandamis PN. Impact of population density and stress adaptation on the internalization of Salmonella in leafy greens. Food Microbiol 2022; 106:104053. [PMID: 35690446 DOI: 10.1016/j.fm.2022.104053] [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: 03/02/2022] [Revised: 04/26/2022] [Accepted: 04/26/2022] [Indexed: 11/17/2022]
Abstract
Salmonella enterica is capable of entering the interior of leafy greens and establishing in the apoplastic area, a phenomenon known as internalization. The ability of internalized bacteria to evade common disinfection practices poses a well-established risk. Our aim was to study the effect of: i) inoculum size and ii) prior adaptation of Salmonella to sublethal stresses, on the internalization of the pathogen in four leafy vegetables. Spinach, lettuce, arugula and chicory were inoculated, by immersion for 2 min at room temperature with: i) Salmonella Enteritidis at 3.0, 4.0, 5.0, 6.0, 7.0 log CFU/mL and ii) non-adapted or adapted S. Enteritidis to acid (in TSB with 1% glucose, incubated for 24 h at 37 °C), cold (in TSB for 7 days at 4 °C), starvation (0.85% NaCl of pH 6.6, 48 h at 37 °C) or desiccation (1.5 h at 42 °C, 4 days at 21 °C) stress at appx 3.5 log CFU/mL). Inoculated leafy greens were subsequently stored at 5 °C and 20 °C for 2 h and 48 h (n = 2 × 2). Population of internalized Salmonella, after surface decontamination with 1% w/v AgNO3, was assessed on selective media. Even the lowest initial bacterial inoculum was adequate for internalization of Salmonella to occur in leafy vegetables. Non-adapted Salmonella inoculum of 7.0 (maximum) and 3.0 log CFU/mL (lowest inoculation level tested) after short storage (2 h) resulted in 3.7-4.3 and 1.3-1.5 log CFU/g internalized bacterial population, respectively. Colonization (including both attachment and internalization processes), as well as internalization process, were positively correlated to initial inoculum level. These processes reached a different plateau beyond which, no further increase in internalization was observed. Adaptation of the pathogen to mild stresses enhanced internalization (P < 0.05), with desiccation- and acid-adapted Salmonella demonstrating the highest internalization capacity, regardless of the vegetable and storage temperature. These findings could contribute to further elucidation of colonization capacity of Salmonella in leafy vegetables and assist in selecting the proper conditions that contribute to the prevention of fresh produce contamination with Salmonella.
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Affiliation(s)
- N C Grivokostopoulos
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55, Athens, Greece
| | - I P Makariti
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55, Athens, Greece
| | - S Tsadaris
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55, Athens, Greece
| | - P N Skandamis
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, 118 55, Athens, Greece.
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12
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Galbraith P, Henry R, McCarthy DT. Plants against pathogens: Effect of significant antimicrobial-producing plants on faecal microbe inactivation throughout the soil profile of stormwater biofilters. WATER RESEARCH 2022; 221:118707. [PMID: 35717708 DOI: 10.1016/j.watres.2022.118707] [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: 12/22/2021] [Revised: 04/20/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Stormwater biofilters have demonstrated promising yet variable removal of faecal microorganisms. Significant antimicrobial-producing plants have been proposed as an inexpensive, safe and easily adaptable component of biofilter design to enhance faecal pathogen treatment. The aim of the present study was to investigate whether significant antimicrobial-producing plants improved faecal bacterial inactivation throughout the biofilter soil profile, focusing on four key treatment zones. These were specifically the top sediment/surface layer; the rhizosphere (soil directly attached to and influenced by plant roots); bulk soil (soil not directly associated with roots); and the submerged/saturated zone. Biofilters were configured with either: (1) no plant; (2) Carex appressa, the most highly recommended plant species in Australian biofilter adoption guidelines; or (3) one of two significant antimicrobial-producing Australian plant species, Melaleuca linariifolia or Melaleuca fulgens (n = 3 each). Following 16 months' maturation, systems were dosed with semi-synthetic stormwater containing faecal bacteria Escherichia coli and Enterococcus faecalis to monitor their ensuing die-off within all major biofilter treatment zones. Bacterial inactivation was generally more rapid in M. fulgens and M. linariifolia than C. appressa biofilters, with E. faecalis demonstrating an overall enhanced resistance to inactivation. Top sediment tended to exhibit the highest inactivation rates, significantly correlated with sunlight exposure. Conversely, the rhizosphere supported comparatively prolonged faecal bacterial survival. The authors recommend further investigation of melaleucas and similar highly antimicrobial-producing plants for enhanced faecal pathogen treatment within biofilters and related treatment contexts.
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Affiliation(s)
- P Galbraith
- Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - R Henry
- Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - D T McCarthy
- Environmental and Public Health Microbiology Laboratory (EPHM Lab), Monash Water for Liveability, Department of Civil Engineering, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
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13
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Adeleke BS, Babalola OO. Meta-omics of endophytic microbes in agricultural biotechnology. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2022. [DOI: 10.1016/j.bcab.2022.102332] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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14
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Lu L, Karunarathna SC, Hyde KD, Suwannarach N, Elgorban AM, Stephenson SL, Al-Rejaie S, Jayawardena RS, Tibpromma S. Endophytic Fungi Associated with Coffee Leaves in China Exhibited In Vitro Antagonism against Fungal and Bacterial Pathogens. J Fungi (Basel) 2022; 8:jof8070698. [PMID: 35887454 PMCID: PMC9317674 DOI: 10.3390/jof8070698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 11/17/2022] Open
Abstract
Coffee endophytes have been studied for almost 74 years, and several studies have demonstrated coffee-endophytic fungi with antibacterial and antifungal potential for human and plant pathogens. In this study, we isolated and identified a total of 235 strains of endophytic fungi from coffee leaf tissues collected in four coffee plantations in Pu’er city, Yunnan province, China. Molecular identification was carried out using maximum likelihood phylogenetic analysis of nuclear ribosomal internal transcribed spacer (ITS1-5.8S rDNA-ITS2) sequences, while the colonization rate and the isolation frequency were also calculated. Two pathogenic fungi (Alternaria alternata and Penicillium digitatum) and two pathogenic bacteria (Pseudomonas syringae and Salmonella enterica subsp. enterica) were used for screening the antagonistic activities of 61 strains of coffee-endophytic fungi by a dual-culture test assay while maximum likelihood phylogenetic analysis confirmed their natural classification. This is the first study of coffee-leaf-endophytic fungal diversity in China, and the results revealed that coffee-endophytic fungi from this study belong to the Ascomycota, distributed among two classes, 10 orders, and 17 families. Concurrently, endophytic fungi isolates distributed in Arthrinium, Biscogniauxia, Daldinia, Diaporthe, and Nigrospora showed strong antagonistic activities against the pathogens. For the pathogens Alternaria alternata and Pseudomonas syringae, Nigrospora XCE-7 showed the best inhibitory effects with inhibition rates of 71.76% and 61.11%, respectively. For the pathogen Penicillium digitatum, Daldinia ME-9 showed the best inhibitory effect with a 74.67% inhibition rate, while Biscogniauxia PTE-7 and Daldinia T5E-1-3 showed the best inhibitory effect with a rate of 60.42% against the pathogen Salmonella enterica subsp. enterica. Overall, our study shows the diversity of coffee endophytes in four coffee-growing areas in Pu’er city, Yunnan province, China, and their potential use as biological control agents against two fungal and two bacterial pathogens.
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Affiliation(s)
- Li Lu
- Center for Yunnan Plateau Biological Resources Protection and Utilization, Yunnan Engineering Research Center of Fruit Wine, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing 655011, China; (L.L.); (S.C.K.)
- Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand; (K.D.H.); (R.S.J.)
- School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand
| | - Samantha C. Karunarathna
- Center for Yunnan Plateau Biological Resources Protection and Utilization, Yunnan Engineering Research Center of Fruit Wine, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing 655011, China; (L.L.); (S.C.K.)
| | - Kevin D. Hyde
- Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand; (K.D.H.); (R.S.J.)
- School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand
- Innovative Institute for Plant Health, Zhong Kai University, Guangzhou 510550, China
| | - Nakarin Suwannarach
- Research Center of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand;
| | - Abdallah M. Elgorban
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh P.O. Box 145111, Saudi Arabia;
| | - Steven L. Stephenson
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA;
| | - Salim Al-Rejaie
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, Riyadh P.O. Box 145111, Saudi Arabia;
| | - Ruvishika S. Jayawardena
- Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand; (K.D.H.); (R.S.J.)
- School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand
| | - Saowaluck Tibpromma
- Center for Yunnan Plateau Biological Resources Protection and Utilization, Yunnan Engineering Research Center of Fruit Wine, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing 655011, China; (L.L.); (S.C.K.)
- Correspondence:
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15
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Xylia P, Chrysargyris A, Botsaris G, Skandamis P, Tzortzakis N. Salmonella Enteritidis survival in different temperatures and nutrient solution pH levels in hydroponically grown lettuce. Food Microbiol 2022; 102:103898. [PMID: 34809930 DOI: 10.1016/j.fm.2021.103898] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/23/2021] [Accepted: 09/08/2021] [Indexed: 11/04/2022]
Abstract
Due to climate change, with contaminated and less fertile soils, and intense weather phenomena, a turn towards hydroponic vegetable production has been made. Hydroponic cultivation of vegetables is considered to be a clean, safe and environmentally friendly growing technique; however, incidence of microbial contamination i.e. foodborne pathogens, might occur, endangering human health. The aim of this study was to investigate the effects of different plant growth stages, pH (values 5, 6, 7, 8) and bacterial inoculum levels (3 and 6 log cfu/mL) on hydroponically cultivated lettuce spiked with Salmonella Enteritidis. The results revealed that the pH and inoculum levels affected the internalization and survival of the pathogen in the hydroponic environment and plant tissue. Younger plants were found to be more susceptible to pathogen internalization compared to older ones. Under the current growing conditions (hydroponics, pH and inoculum levels), no leaf internalization was observed at all lettuce growth stages, despite the bacterium presence in the hydroponic solution. Noticeably, bacteria load at the nutrient solution was lower in low pH levels. These results showed that bacterium presence initiates plant response as indicated by the increased phenols, antioxidants and damage index markers (H2O2, MDA) in order for the plant to resist contamination by the invader. Nutrient solution management can result in Taylor-made recipes for plant growth and possible controlling the survival and growth of S. Enteritidis by pH levels.
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Affiliation(s)
- Panayiota Xylia
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus
| | - Antonios Chrysargyris
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus
| | - George Botsaris
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus
| | - Panagiotis Skandamis
- Faculty of Food Science & Technology, Agricultural University of Athens, Athens, Greece
| | - Nikolaos Tzortzakis
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus.
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16
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Grivokostopoulos NC, Makariti IP, Hilaj N, Apostolidou Z, Skandamis PN. Internalization of Salmonella in Leafy Greens and Impact on Acid Tolerance. Appl Environ Microbiol 2022; 88:e0224921. [PMID: 35108086 PMCID: PMC8939352 DOI: 10.1128/aem.02249-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/26/2022] [Indexed: 11/20/2022] Open
Abstract
Salmonella colonizes the surface or the inner part of leafy greens, while the ability of internalized bacteria to evade common disinfection practices may pose a considerable risk. Hereby, we aimed to assess how the colonization and internalization of Salmonella spp. (i) vary with the type of leafy green, the storage conditions (temperature, time), and Salmonella serovar at phenotypic and gene transcriptional level (regarding stress- and virulence- or type III secretion system [T3SS]-associated genes) and (ii) potentially impact the survival of the pathogen against subsequent exposure at lethal pH (2.7), mimicking the gastric acidity. Internalized Salmonella reached 3.0 to 5.0 log CFU/g depending on storage conditions and vegetable, with spinach and chicory allowing the highest (P < 0.05) internalization. Prolonged storage (48 h) at 20°C increased the recovery of internalized Salmonella in spinach and green amaranth by 1.0 to 1.5 log units. Colonization of Salmonella on/in leafy vegetables induced the transcription (maximum fold change [FCmax], ∼2,000) of T3SS-related genes. Interserovar variation regarding the internalization ability of Salmonella was observed only in lettuce and green amaranth in a time- and temperature-dependent manner. Attached cells exhibited higher survival rates against low pH than the internalized subpopulation; however, habituation at 20°C in lettuce and amaranth induced acid tolerance to internalized cells, manifested by the 1.5 to 2.0 log CFU/g survivors after 75 min at pH 2.7. Habituation of Salmonella in vegetable extracts sensitized it toward acid, while indigenous microbiota had limited impact on acid resistance of the organism. These findings reveal physiological aspects of Salmonella colonizing leafy vegetables that could be useful in fresh produce microbial risk assessment. IMPORTANCE Consumption of leafy greens has been increasingly associated with foodborne illnesses, and their contamination could occur at pre- and/or postharvest level. Human pathogens may become passively or actively internalized in plant tissues, thereby escaping decontamination procedures. Plant colonization may impact bacterial physiology such as stress resistance and virulence. In this study, it was demonstrated that internalization of Salmonella spp., at the postharvest level, varied with type of vegetable, serovar, and storage conditions. Attached and internalized subpopulations of Salmonella on/in leafy greens showed distinct physiological responses regarding transcriptional changes of stress- and virulence-associated genes, as well as survival capacity against subsequent exposure to lethal pH (2.7). These findings could contribute to a better understanding and potential (re)definition of the risk of enteric pathogens colonizing leafy greens, as well as to the design of intervention strategies aiming to improve the microbiological safety of fresh produce.
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Affiliation(s)
- N. C. Grivokostopoulos
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - I. P. Makariti
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - N. Hilaj
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Z. Apostolidou
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - P. N. Skandamis
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
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17
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Alufasi R, Parawira W, Stefanakis AI, Lebea P, Chakauya E, Chingwaru W. Internalisation of Salmonella spp. by Typha latifolia and Cyperus papyrus in vitro and implications for pathogen removal in Constructed Wetlands. ENVIRONMENTAL TECHNOLOGY 2022; 43:949-961. [PMID: 32795219 DOI: 10.1080/09593330.2020.1811395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
ABSTRACTFreshwater contamination by enteric pathogens is implicated in the high frequency of diarrhoeal diseases in low to middle income countries, typically due to poor wastewater management. Constructed Wetlands are a cost-effective and sustainable alternative to conventional/mechanical treatment technologies, but the pathogen removal mechanisms in Constructed Wetlands are not fully understood. This study investigated for the first time the internalisation of Salmonella spp. by Typha latifolia and Cyperus papyrus in hydroponic microcosms. Presence of Salmonella spp. within roots, rhizomes and shoots was assayed using agar-based methods over a period of 12 days. Concentration of Salmonella spp. in growth media showed 2.7 and 4.8 log unit reduction with T. latifolia and C. papyrus, respectively, and 1.8 and 6.0 log unit in unplanted units. Salmonella spp. was recovered from root and rhizome tissues of T. latifolia (up to 4.4 logCFU/g) and C. papyrus (up to 3.4 logCFU/g), and the bacteria were highly concentrated in the epidermis and cortex. However, Salmonella spp. was not detected in the stems and leaves of the two plant species. The present study demonstrates for the first time that these macrophytes internalise cells of Salmonella spp., which could be one pathogen removal mechanism employed by wetland plants.
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Affiliation(s)
- Richwell Alufasi
- Biological Sciences Department, Bindura University of Science Education, Bindura, Zimbabwe
| | - Wilson Parawira
- Biological Sciences Department, Bindura University of Science Education, Bindura, Zimbabwe
| | | | | | - Ereck Chakauya
- AUDA-NEPAD Southern Africa Network for Biosciences (SANBio) and Council for Scientific and Industrial Research (CSIR) Advanced Agriculture and Food, Pretoria, South Africa
| | - Walter Chingwaru
- Biological Sciences Department, Bindura University of Science Education, Bindura, Zimbabwe
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18
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Guillén S, Marcén M, Fau E, Mañas P, Cebrián G. Relationship between growth ability, virulence, and resistance to food-processing related stresses in non-typhoidal Salmonellae. Int J Food Microbiol 2022; 361:109462. [PMID: 34749188 DOI: 10.1016/j.ijfoodmicro.2021.109462] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/01/2021] [Accepted: 10/25/2021] [Indexed: 11/29/2022]
Abstract
The ability of Salmonella to resist and adapt to harsh conditions is one of the major features that have made this microorganism such a relevant health hazard. However, the impact of these resistance responses on other aspects of Salmonella physiology, such as virulence and growth ability, is still not fully understood. The objective of this study was to determine the maximum growth rates (in three different media), virulence (adhesion and invasion of Caco-2 cells), and other phenotypic characteristics (biofilm-forming ability and antimicrobial resistance) of 23 Salmonella strains belonging to different serovars, and to compare them with their previously determined stress resistance parameters. Significant differences (p < 0.05) in growth rates, virulence, and biofilm-forming ability were found among the 23 strains studied. Nevertheless, whereas less than 3-fold change between the lowest and the highest growth rate was observed, the percentage of cells capable of invading Caco-2 cells varied more than 100-fold, that to form biofilms more than 30-fold, and the antibiotic MICs varied up to 512-fold, among the different strains. Results indicate that those strains with the highest cell adhesion ability were not always the most invasive ones and suggest that, in general terms, a higher stress resistance did not imply a reduced growth ability (rate). Similarly, no association between stress resistance and biofilm formation ability (except for acid stress) or antibiotic resistance (with minor exceptions) was found. Our data also suggest that, in Salmonella, acid stress resistance would be associated with virulence, since a positive correlation of that trait with adhesion and a negative correlation with invasion was found. This study contributes to a better understanding of the physiology of Salmonella and the relationship between bacterial stress resistance, growth ability, and virulence. It also provides new data regarding intra-specific variability of a series of phenotypic characteristics of Salmonella that are relevant from the food safety perspective.
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Affiliation(s)
- Silvia Guillén
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - María Marcén
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Ester Fau
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Pilar Mañas
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), Zaragoza, Spain
| | - Guillermo Cebrián
- Departamento de Producción Animal y Ciencia de los Alimentos, Facultad de Veterinaria, Instituto Agroalimentario de Aragón - IA2 - (Universidad de Zaragoza-CITA), Zaragoza, Spain.
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19
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Jongman M, Carmichael P, Loeto D, Gomba A. Advances in the use of biocontrol applications in preharvest and postharvest environments: A food safety milestone. J Food Saf 2021. [DOI: 10.1111/jfs.12957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Patricia Carmichael
- Department of Agricultural Research and Specialists Services Malkerns Eswatini
| | - Daniel Loeto
- Department of Biological Sciences University of Botswana Gaborone Botswana
| | - Annancietar Gomba
- National Institute for Occupational Health National Health Laboratory Service Johannesburg South Africa
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20
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George AS, Brandl MT. Plant Bioactive Compounds as an Intrinsic and Sustainable Tool to Enhance the Microbial Safety of Crops. Microorganisms 2021; 9:2485. [PMID: 34946087 PMCID: PMC8704493 DOI: 10.3390/microorganisms9122485] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/20/2021] [Accepted: 11/26/2021] [Indexed: 12/25/2022] Open
Abstract
Outbreaks of produce-associated foodborne illness continue to pose a threat to human health worldwide. New approaches are necessary to improve produce safety. Plant innate immunity has potential as a host-based strategy for the deactivation of enteric pathogens. In response to various biotic and abiotic threats, plants mount defense responses that are governed by signaling pathways. Once activated, these result in the release of reactive oxygen and nitrogen species in addition to secondary metabolites that aim at tempering microbial infection and pest attack. These phytochemicals have been investigated as alternatives to chemical sanitization, as many are effective antimicrobial compounds in vitro. Their antagonistic activity toward enteric pathogens may also provide an intrinsic hurdle to their viability and multiplication in planta. Plants can detect and mount basal defenses against enteric pathogens. Evidence supports the role of plant bioactive compounds in the physiology of Salmonella enterica, Escherichia coli, and Listeria monocytogenes as well as their fitness on plants. Here, we review the current state of knowledge of the effect of phytochemicals on enteric pathogens and their colonization of plants. Further understanding of the interplay between foodborne pathogens and the chemical environment on/in host plants may have lasting impacts on crop management for enhanced microbial safety through translational applications in plant breeding, editing technologies, and defense priming.
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Affiliation(s)
| | - Maria T. Brandl
- Produce Safety and Microbiology Research Unit, United States Department of Agriculture, Agricultural Research Service, Albany, CA 94710, USA;
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21
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Chahar M, Kroupitski Y, Gollop R, Belausov E, Melotto M, Sela-Saldinger S. Determination of Salmonella enterica Leaf Internalization Varies Substantially According to the Method and Conditions Used to Assess Bacterial Localization. Front Microbiol 2021; 12:622068. [PMID: 34803936 PMCID: PMC8603913 DOI: 10.3389/fmicb.2021.622068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 08/27/2021] [Indexed: 11/13/2022] Open
Abstract
In a previous study, comparing the internalization of S. enterica serovar Typhimurium in various leaves by confocal microscopy, we have demonstrated that the pathogen failed to internalize tomato leaves. Numerous reasons may account for these findings, yet one such factor might be the methodology employed to quantify leaf internalization. To this end, we have systematically studied leaf localization of a Green-fluorescent protein-labeled Salmonella strain in tomato, lettuce, and Arabidopsis leaves by surface sterilization and enumeration of the surviving bacteria, side by side, with confocal microscopy observations. Leaf sterilization was performed using either sodium hypochlorite, silver nitrate, or ethanol for 1 to 7min. The level of internalization varied according to the type of disinfectant used for surface sterilization and the treatment time. Treatment of tomato leaves with 70% ethanol for up to 7min suggested possible internalization of Salmonella, while confocal microscopy showed no internalization. In the case of in lettuce and Arabidopsis leaves, both the plate-count technique and confocal microscopy demonstrated considerable Salmonella internalization thought different sterilization conditions resulted in variations in the internalization levels. Our findings highlighted the dependency of the internalization results on the specific disinfection protocol used to determine bacterial localization. The results underscore the importance of confocal microscopy in validating a particular surface sterilization protocol whenever a new pair of bacterial strain and plant cultivar is studied.
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Affiliation(s)
- Madhvi Chahar
- Department of Food Sciences, The Volcani Center, Institute for Postharvest and Food Sciences, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Yulia Kroupitski
- Department of Food Sciences, The Volcani Center, Institute for Postharvest and Food Sciences, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Rachel Gollop
- Department of Food Sciences, The Volcani Center, Institute for Postharvest and Food Sciences, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Eduard Belausov
- Microscopy Unit, Plant Sciences, Ornamental Plants and Agricultural Biotechnology, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Maeli Melotto
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Shlomo Sela-Saldinger
- Department of Food Sciences, The Volcani Center, Institute for Postharvest and Food Sciences, Agriculture Research Organization, Rishon-LeZion, Israel
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22
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Esteban-Cuesta I, Labrador M, Hunt K, Reese S, Fischer J, Schwaiger K, Gareis M. Phenotypic and Genetic Comparison of a Plant-Internalized and an Animal-Isolated Salmonella Choleraesuis Strain. Microorganisms 2021; 9:microorganisms9081554. [PMID: 34442630 PMCID: PMC8398053 DOI: 10.3390/microorganisms9081554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/05/2021] [Accepted: 07/16/2021] [Indexed: 11/16/2022] Open
Abstract
Contamination of fresh produce with human pathogens poses an important risk for consumers, especially after raw consumption. Moreover, if microorganisms are internalized, no removal by means of further hygienic measures would be possible. Human pathogenic bacteria identified in these food items are mostly of human or animal origin and an adaptation to this new niche and particularly for internalization would be presumed. This study compares a plant-internalized and an animal-borne Salmonella enterica subsp. enterica serovar Choleraesuis aiming at the identification of adaptation of the plant-internalized strain to its original environment. For this purpose, a phenotypical characterization by means of growth curves under conditions resembling the indigenous environment from the plant-internalized strain and further analyses using Pulsed-field gel electrophoresis and Matrix-assisted laser desorption ionization time of flight spectrometry were assessed. Furthermore, comparative genomic analyses by means of single nucleotide polymorphisms and identification of present/absent genes were performed. Although some phenotypical and genetic differences could be found, no signs of a specific adaptation for colonization and internalization in plants could be clearly identified. This could suggest that any Salmonella strain could directly settle in this niche without any evolutionary process being necessary. Further comparative analysis including internalized strains would be necessary to assess this question. However, these kinds of strains are not easily available.
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Affiliation(s)
- Irene Esteban-Cuesta
- Chair of Food Safety, Veterinary Faculty, LMU Munich, 85764 Oberschleissheim, Germany; (K.H.); (K.S.); (M.G.)
- Correspondence:
| | - Mirian Labrador
- Departamento de Producción Animal y Ciencia de los Alimentos, Veterinary Faculty, Instituto Agroalimentario de Aragon-IA2, University of Zaragoza-CITA, 50013 Zaragoza, Spain;
| | - Katharina Hunt
- Chair of Food Safety, Veterinary Faculty, LMU Munich, 85764 Oberschleissheim, Germany; (K.H.); (K.S.); (M.G.)
| | - Sven Reese
- Chair of Anatomy, Histology and Embryology, Department of Veterinary Sciences, Faculty of Veterinary Medicine, LMU Munich, 80539 Munich, Germany;
| | - Jennie Fischer
- National Salmonella Reference Laboratory, Unit Food Microbiology, Host-Pathogen-Interactions, Department of Biological Safety, German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung—BfR), 12277 Berlin, Germany;
| | - Karin Schwaiger
- Chair of Food Safety, Veterinary Faculty, LMU Munich, 85764 Oberschleissheim, Germany; (K.H.); (K.S.); (M.G.)
- Unit of Food Hygiene and Technology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, 1220 Vienna, Austria
| | - Manfred Gareis
- Chair of Food Safety, Veterinary Faculty, LMU Munich, 85764 Oberschleissheim, Germany; (K.H.); (K.S.); (M.G.)
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23
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An overview on endophytic bacterial diversity habitat in vegetables and fruits. Folia Microbiol (Praha) 2021; 66:715-725. [PMID: 34259998 DOI: 10.1007/s12223-021-00896-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/30/2021] [Indexed: 01/02/2023]
Abstract
Nowadays, scientific research revolution is going on in many areas, and the human health is one of them. However, in the earlier studies, it was observed that most of the people health in the world affects by consumptions of contaminated food which is dangerous for human health and country economy. Recent studies showed that the fresh vegetables and fruits are the major habitat for endophytic bacterial communities. Salmonella and Escherichia coli both are the very common bacteria founds in fresh vegetables and fruits. Generally, many people eat vegetables and fruits without cooking (in the form of salad). The continued assumption of such food increases the health risk factor for foodborne diseases. So, from the last decades, many researchers working to understand about the relationship of endophytic microbes with plants either isolated bacteria are pathogenic or nonpathogenic. Moreover, most of the endophytes were identified by using 16S rRNA sequencing method. Hence, this review elaborates on the differences and similarities between nonpathogenic and pathogenic endophytes in terms of host plant response, colonization strategy, and genome content. Furthermore, it is emphasized on the environmental effects and biotic interactions within plant microbiota that influence pathogenesis and the pathogenesis.
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Reid AN, Conklin C, Beaton K, Donahue N, Jackson E, LoCASCIO B, Marsocci C, Szemreylo E, Szemreylo K. Inoculum Preparation Conditions Influence Adherence of Salmonella enterica Serovars to Red Leaf Lettuce (Lactuca sativa). J Food Prot 2021; 84:857-868. [PMID: 33411904 DOI: 10.4315/jfp-20-301] [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: 07/29/2020] [Accepted: 12/21/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT Salmonella enterica has been increasingly linked to outbreaks involving consumption of fresh produce. Although researchers have identified genes whose products are involved in mediating S. enterica-plant interactions, the use of various experimental approaches, serovars, and plant types has generated variable and conflicting data. The purpose of this study was to determine whether conditions under which inocula are prepared for in vitro plant interaction studies influence the outcome of these studies. Seven S. enterica serovars were grown in media that differed in salinity and physical state with incubation at 25 or 37°C. These cultures were then used to inoculate red leaf lettuce, and adherent microbes were subsequently recovered. Although all Salmonella serovars were influenced by inoculum preparation conditions, the amount of variation differed. Analysis of pooled serovar data revealed that inocula prepared from either agar plates or biphasic cultures had higher levels of interaction with red leaf lettuce than those prepared from broth cultures. Incubation at 37°C enhanced adherence after 30 s or 5 days of contact time, and adherence after 1 h of contact time was increased in low-salt medium. Broth inoculum cultures were highly influenced by medium salinity and incubation temperature, whereas plate and biphasic inoculum cultures were only minimally affected. Therefore, inocula prepared from bacteria grown on plates or in biphasic culture would be most suitable for evaluation of strategies used to interfere with plant-Salmonella interactions. However, pooled data mask serovar-specific responses, and care should be taken when extrapolating these findings to individual serovars. The previous association of a serovar with outbreaks involving leafy greens was not correlated with levels of interaction with red leaf lettuce, suggesting that the occurrence of these serovars in or on these commodities does not reflect their fitness in the plant environment. HIGHLIGHTS
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Affiliation(s)
- Anne N Reid
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Courtney Conklin
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Kimberly Beaton
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Nora Donahue
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Emily Jackson
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Brianna LoCASCIO
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Cristina Marsocci
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Emily Szemreylo
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
| | - Katlin Szemreylo
- Department of Biology and Biomedical Sciences, Salve Regina University, 100 Ochre Point Avenue, Newport, Rhode Island 02840, USA
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A Double-Edged Sword of Surfactant Effect on Hydrophobic Surface Broccoli Leaf as a Model Plant: Promotion of Pathogenic Microbial Contamination and Improvement to Disinfection Efficiency of Ozonated Water. Processes (Basel) 2021. [DOI: 10.3390/pr9040679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Pathogenic microbial contamination is significantly influenced by the crop surface properties and surfactant use, which are crucial factors for the postharvest washing process. However, there is little information on the interaction between surfactant and food pathogens on food crops. Thus, this study (1) investigated whether the attachment of Salmonella increases as pesticides denature epicuticular wax crystals and (2) tested if the antibacterial effect of ozonated water can be improved on waxy produce surfaces by adding surfactant to ozonated water. As a result, significantly lower levels of Salmonella Typhimurium attached to waxy leaf surfaces than they did to glossy and pesticide-treated waxy leaf surfaces (3.28 as opposed to 4.10 and 4.32 Log colony forming units (CFU)/cm2, respectively), suggesting that the pesticide containing a surfactant application increased the attachment of S. Typhiumurium on waxy leaf surfaces. There was no significant washing effect on waxy leaf surfaces washed with ozonated water. On the other hand, S. Typhimurium were not detected on waxy leaf surfaces after washing with surfactant-added ozonated water.
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26
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Deblais L, Miller SA, Rajashekara G. Impact of Plant Pathogen Infection on Salmonella enterica subsp. enterica Serotype Typhimurium Persistence in Tomato Plants. J Food Prot 2021; 84:563-571. [PMID: 33180909 DOI: 10.4315/jfp-20-291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/09/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT We investigated whether the co-occurrence of phytopathogens (Clavibacter michiganensis subsp. michiganensis [Cmm] and Xanthomonas gardneri [Xg]) frequently encountered in tomato production and Salmonella enterica subsp. enterica serotype Typhimurium (strain JSG626) affects the persistence of these pathogens in tomato plant tissues during the early stages of plant growth. Cmm increased the recovery of Salmonella Typhimurium (up to 1.8 log CFU per plant at 21 days postinoculation [DPI]) from coinoculated tomato plants compared with plants inoculated with Salmonella Typhimurium alone (P < 0.05). Xg had no effect on Salmonella Typhimurium persistence in the plants. Increased persistence of Salmonella Typhimurium was also observed when it was inoculated 7 days after Cmm inoculation of the same plant (P < 0.05). In contrast, Salmonella Typhimurium reduced the population of both Cmm and Xg (up to 1.5 log CFU per plant at 21 DPI; P < 0.05) in coinoculated plants compared with plants inoculated with Cmm or Xg alone. The Xg population increased (1.16 log CFU per plant at 21 DPI; P < 0.05) when Salmonella Typhimurium was inoculated 7 days after Xg inoculation compared with plants inoculated with Xg alone. Our findings indicate that the type of phytopathogen present in the phyllosphere and inoculation time influence the persistence of Salmonella Typhimurium JSG626 and its interactions with phytopathogens cocolonized in tomato plants. Salmonella reduced the phytopathogen load in plant tissues, and Cmm enhanced the recovery of Salmonella from the coinoculated plant tissues. However, further investigations are needed to understand the mechanisms behind these interactions. HIGHLIGHTS
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Affiliation(s)
- Loïc Deblais
- Department of Veterinary Preventive Medicine, Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA.,Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA.,(ORCID: https://orcid.org/0000-0002-6290-3956 [L.D.])
| | - Sally A Miller
- Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA
| | - Gireesh Rajashekara
- Department of Veterinary Preventive Medicine, Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA
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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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28
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Clairmont LK, Coristine A, Stevens KJ, Slawson RM. Factors influencing the persistence of enteropathogenic bacteria in wetland habitats and implications for water quality. J Appl Microbiol 2020; 131:513-526. [PMID: 33274572 DOI: 10.1111/jam.14955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/12/2020] [Accepted: 11/29/2020] [Indexed: 11/28/2022]
Abstract
AIMS To better understand the persistence dynamics of enteropathogenic bacteria in freshwater wetland habitats, we constructed lab-scale mesocosms planted with two different wetland plant species using a subsurface flow wetland design. Mesocosms were treated with either a high-quality or a poor-quality water source to examine the effects of water quality exposure and plant species on Escherichia coli, Salmonella spp. and Enterococcus spp. in the rhizoplane, rhizosphere and water of wetland habitats. METHODS AND RESULTS Quantities of study micro-organisms were detected using real-time PCR in wetland mesocosms. A combination of molecular and culture-based methods was also used to enumerate these organisms from surface water and plant material at high, medium and poor water quality sites in the field. We found that all three enteropathogenic micro-organisms were influenced by microhabitat type and plant species. Organisms differed with respect to their predominant microhabitat and the extent of persistence associated with wetland plant species in the mesocosm study. Of the monitored pathogens, only E. coli was influenced by both water quality treatment and plant species. Salmonella spp. quantities in the rhizoplane consistently increased in all treatments over the course of the mesocosm experiment. CONCLUSIONS Plant species selection appears to be an overlooked aspect of constructed wetland design with respect to the removal of enteropathogenic micro-organisms. Escherichia coli and Enterococcus concentrations in wetland outflow were significantly different between the two plant species tested, with Enterococcus concentrations being significantly higher in mesocosms planted with Phalaris arundinaceae and E. coli concentrations being higher in mesocosms planted with Veronica anagallis-aquatica. Furthermore, there is evidence that the rhizoplane is a significant reservoir for Salmonella spp. within wetland habitats. SIGNIFICANCE AND IMPACT OF THE STUDY This is the first time that Salmonella spp. has been shown to proliferate under natural conditions within the rhizoplane. This will contribute to our understanding of wetland removal mechanisms for enteropathogenic bacteria. This study identifies the rhizoplane as a potentially important reservoir for human pathogenic micro-organisms and warrants additional study to establish whether this finding is applicable in non-wetland habitats.
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Affiliation(s)
| | - A Coristine
- Wilfrid Laurier University, Waterloo, ON, Canada
| | - K J Stevens
- Wilfrid Laurier University, Waterloo, ON, Canada
| | - R M Slawson
- Wilfrid Laurier University, Waterloo, ON, Canada
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29
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Arienzo A, Murgia L, Fraudentali I, Gallo V, Angelini R, Antonini G. Microbiological Quality of Ready-to-Eat Leafy Green Salads during Shelf-Life and Home-Refrigeration. Foods 2020; 9:foods9101421. [PMID: 33049952 PMCID: PMC7601731 DOI: 10.3390/foods9101421] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 11/23/2022] Open
Abstract
The market of ready-to-eat leafy green salads is experiencing a noticeable growth in Europe. Since they are intended to be consumed without additional treatments, these ready-to-eat products are associated with a high microbiological risk. The aim of this work was to evaluate the microbiological quality and safety of ready-to-eat leafy green salads sold in widespread supermarket chains in Lazio, Italy, on the packaging date during shelf-life and during home-refrigeration. The study also aimed to determine the differences between low-, medium-, and high-cost products. Salmonella spp. and L. monocytogenes were chosen as safety indicators as specified by European regulations while total aerobic mesophilic bacteria and Escherichia coli were chosen as quality indicators as suggested by national guidelines. Analyses were performed following the ISO standards and in parallel for the evaluation of total aerobic mesophilic bacteria, with an alternative colorimetric system, the Micro Biological Survey method, in order to propose a simple, affordable and accurate alternative for testing the microbiological quality of products, especially suitable for small and medium enterprises and on-site analyses. The study revealed high, unsatisfactory, total bacterial loads in all analyzed samples on the packaging date and expiry date and a very high prevalence of Salmonella spp. (67%) regardless of the selected varieties and cost categories; L. monocytogenes was not recovered aligning with the results obtained in other studies.
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Affiliation(s)
- Alyexandra Arienzo
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (A.A.); (I.F.); (R.A.)
| | - Lorenza Murgia
- Interuniversity Consortium INBB National Institute of Biostructures and Biosystems, Viale delle Medaglie d’Oro, 305, 00136 Rome, Italy; (L.M.); (V.G.)
| | - Ilaria Fraudentali
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (A.A.); (I.F.); (R.A.)
| | - Valentina Gallo
- Interuniversity Consortium INBB National Institute of Biostructures and Biosystems, Viale delle Medaglie d’Oro, 305, 00136 Rome, Italy; (L.M.); (V.G.)
| | - Riccardo Angelini
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (A.A.); (I.F.); (R.A.)
| | - Giovanni Antonini
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (A.A.); (I.F.); (R.A.)
- Interuniversity Consortium INBB National Institute of Biostructures and Biosystems, Viale delle Medaglie d’Oro, 305, 00136 Rome, Italy; (L.M.); (V.G.)
- Correspondence:
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30
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Microbial colonization on the leaf surfaces of different genotypes of Napier grass. Arch Microbiol 2020; 203:335-346. [PMID: 32945890 DOI: 10.1007/s00203-020-02025-4] [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: 05/24/2020] [Revised: 08/13/2020] [Accepted: 09/02/2020] [Indexed: 01/06/2023]
Abstract
To address correlations between population sizes of microbes on the leaf surfaces and leaf morphological and physicochemical properties, various leaf morphological and physicochemical features as possible predictors of microbial population sizes on the leaf surfaces of four Napier grass cultivars were assessed. Results indicated microbes except for lactic acid bacteria (LAB) preferred to colonize the leaf surfaces bearing trichomes, and their population sizes were significantly correlated with trichomes, especially for yeasts. The population sizes of microbes were positively correlated with soluble sugar content (p < 0.05). Furthermore, no significant correlation was found between population sizes of microbes and wax content, except for yeasts. The multivariate regression trees (MRT) analysis showed different genotypes of leaf-microbe system could be characterized by four-leaf attributes with soluble sugar of leaf tissues being the primary explanatory attribute. Leaves with soluble sugar content below 9.72 mg g-1 fresh weight (FW) were rarely colonized. For leaves with soluble sugar content above 9.72 mg g-1 FW, water content was the next explanatory leaf attribute, followed by wax content on the leaf surfaces. Leaves with higher water content (> 73%) were more colonized, and small microbial population was associated with higher wax content (> 10.66 mg g-1 dry matter). In conclusion, leaf chemical attributes have a higher contribution than morphological structure properties in determining population sizes of microbes on the leaf surfaces. The exuded soluble sugar and protein promote the development of microbial populations. For different genotypes of leaf-microbe system, the relationship between microbial abundance on their leaf surfaces and leaf morphological structure or physicochemical properties may be predicted by the MRT. Population sizes of microbes are primarily influenced by soluble sugar content under the water-rich conditions.
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Chiudioni F, Marcheggiani S, Puccinelli C, Mancini L. Interaction between bacterial enteric pathogens and aquatic macrophytes. Can Salmonella be internalized in the plants used in phytoremediation processes? INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2020; 23:18-25. [PMID: 32634324 DOI: 10.1080/15226514.2020.1786797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The environment is considered a reservoir of pathogens and a possible source of infection for animals and humans. The association between enteric pathogens and food plants has been demonstrated in several studies, while few studies have addressed possible interactions between human pathogens and aquatic plants. This study, performed by setting mesocosms, evaluates the interaction between an enteric pathogen (Salmonella enterica serovar Napoli, S. Napoli) and a macrophyte (Phragmites australis (Cav.) Trin. ex Steudel) and the possible ability of the bacterium to internalize into the plant. The results show that S. Napoli concentration decreased gradually in growth solution without plants (control) while it was able to persist adhering to submerged parts of plants in treated mesocosms. The adhesion of the bacterium remained stable for 20 days, then decreased gradually until the end of the experiment. In addition, S. Napoli was able to internalize and colonize stems and leaves. In conclusion, the study suggests that macrophytes can represent an alternative environmental reservoir of pathogens for humans and animals. The adhesion to roots and rhizomes and the internalization could contribute to the bacterial persistence in the aquatic ecosystems by playing an important role in ecology and transmission of pathogens.
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Affiliation(s)
- Filippo Chiudioni
- Department of Enviroment and Health, Istituto Superiore di Sanità (ISS), Rome, Italy
| | - Stefania Marcheggiani
- Department of Enviroment and Health, Istituto Superiore di Sanità (ISS), Rome, Italy
| | - Camilla Puccinelli
- Department of Enviroment and Health, Istituto Superiore di Sanità (ISS), Rome, Italy
| | - Laura Mancini
- Department of Enviroment and Health, Istituto Superiore di Sanità (ISS), Rome, Italy
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32
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Cui Y, Liu DA, Chen J. Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli on Vegetable Seeds Contaminated by Direct Contact with Artificially Inoculated Soil during Germination. J Food Prot 2020; 83:1218-1226. [PMID: 32221551 DOI: 10.4315/jfp-20-021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/17/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT Contaminated vegetable seeds have been identified as a potential source of foodborne bacterial pathogens. This study was undertaken to observe the behavior of Salmonella and enterohemorrhagic Escherichia coli (EHEC) on vegetable seeds, contaminated by direct contact with artificially inoculated soil, during germination. Sterile sandy soil inoculated with lyophilized cells of four individual strains of Salmonella or EHEC (three O157:H7 strains and one O104:H4 strain) was mixed with sanitized seeds (2 g) of alfalfa, fenugreek, lettuce, and tomato at 20°C for 1 h. The contaminated seeds were germinated on 1% water agar at 25°C for 9 days in the dark. Populations of Salmonella and EHEC on various tissues (seed coat, root, cotyledon, and stem, etc.) of sprouts and seedlings were determined every other day over the germination period. Overall, 70.4 and 72.4% of collected tissue samples (n = 544) tested positive for Salmonella and EHEC, respectively. In general, the mean populations of Salmonella and EHEC on sprout and seedling tissues increased with the prolongation of germination time. Seed coats had the highest bacterial counts (4.00 to 4.06 log CFU/0.01 g), followed by the root (3.36 to 3.38 log CFU/0.01 g), cotyledon (3.13 to 3.38 log CFU/0.01 g), and stem tissues (2.67 to 2.84 log CFU/0.01 g). On average, tissue sections of fenugreek sprouts and lettuce seedlings had significantly higher (P < 0.05) numbers of Salmonella and EHEC cells than that of alfalfa sprouts and tomato seedlings. Data suggest that the growth and dissemination of Salmonella and EHEC cells on alfalfa, fenugreek, lettuce, and tomato sprout and seedling tissues are influenced by the type of vegetable seeds and sprout and seedling tissues involved. The study provides useful information on the fate of two important foodborne bacterial pathogens on selected vegetable seeds, contaminated by direct contact with inoculated soil, during the germination process. HIGHLIGHTS
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Affiliation(s)
- Yue Cui
- Department of Food Science and Technology, The University of Georgia, Griffin, Georgia 30223-1797, USA.,College of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, 050081, People's Republic of China
| | - D A Liu
- Department of Food Science and Technology, The University of Georgia, Griffin, Georgia 30223-1797, USA
| | - Jinru Chen
- Department of Food Science and Technology, The University of Georgia, Griffin, Georgia 30223-1797, USA
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Wang CJ, Thanarut C, Sun PL, Chung WH. Colonization of human opportunistic Fusarium oxysporum (HOFo) isolates in tomato and cucumber tissues assessed by a specific molecular marker. PLoS One 2020; 15:e0234517. [PMID: 32530955 PMCID: PMC7292389 DOI: 10.1371/journal.pone.0234517] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/26/2020] [Indexed: 12/31/2022] Open
Abstract
Fusarium oxysporum is a large complex cosmopolitan species composed of plant pathogens, human opportunistic pathogens, and nonpathogenic isolates. Many plant pathogenic strains are known based on host plant specificity and the large number of plant species attacked. F. oxysporum is an opportunistic pathogen in humans with a compromised immune system. The objectives of this study were: (1) to develop a specific marker to detect human opportunistic F. oxysporum (HOFo) isolates; (2) to determine whether or not HOFo isolates can colonize and cause disease symptoms in plants; and (3) to assess Taiwan isolates sensitivity to two agro-fungicides. The primer pair, Primer 5/ST33-R, specifically amplifying Taiwan and international reference HOFo isolates was developed and used to detect and assess the distribution of a Taiwan isolate in inoculated tomato plants and tomato and cucumber fruit. Taiwan HOFo isolate MCC2074 was shown to colonize tomato roots, hypocotyls, and cotyledons, but did not show any visible symptoms. Four days after surface inoculation of tomato and cucumber fruit with the same isolate, MCC2074 was detected in the pericarp and locular cavities of both tomato and cucumber fruit and in columella of tomato fruit. Three Taiwan HOFo isolates were found to be moderately sensitive to azoxystrobin and highly sensitive to difenconazole.
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Affiliation(s)
- Chao-Jen Wang
- Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan
| | - Chinnapan Thanarut
- Faculty of Agricultural Production, Division of Pomology Maejo University, Chiangmai, Thailand
| | - Pei-Lun Sun
- Department of Dermatology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Wen-Hsin Chung
- Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan
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Factors Required for Adhesion of Salmonella enterica Serovar Typhimurium to Corn Salad (Valerianella locusta). Appl Environ Microbiol 2020; 86:AEM.02757-19. [PMID: 32033951 DOI: 10.1128/aem.02757-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/04/2020] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica is a foodborne pathogen often leading to gastroenteritis and is commonly acquired by consumption of contaminated food of animal origin. However, frequency of outbreaks linked to the consumption of fresh or minimally processed food of nonanimal origin is increasing. New infection routes of S. enterica by vegetables, fruits, nuts, and herbs have to be considered. This leads to special interest in S. enterica interactions with leafy products, e.g., salads, that are mainly consumed in a minimally processed form. The attachment of S. enterica to salad is a crucial step in contamination, but little is known about the bacterial factors required and mechanisms of adhesion. S. enterica possesses a complex set of adhesive structures whose functions are only partly understood. Potentially, S. enterica may deploy multiple adhesive strategies for adhering to various salad species and other vegetables. In this study, we systematically analyzed the contributions of the complete adhesiome, of lipopolysaccharide (LPS), and of flagellum-mediated motility of S. enterica serovar Typhimurium (STM) in adhesion to Valerianella locusta (corn salad). We deployed a reductionist, synthetic approach to identify factors involved in the surface binding of STM to leaves of corn salad, with particular regard to the expression of all known adhesive structures, using the Tet-on system. This work reveals the contribution of Saf fimbriae, type 1 secretion system-secreted BapA, an intact LPS, and flagellum-mediated motility of STM in adhesion to corn salad leaves.IMPORTANCE Transmission of gastrointestinal pathogens by contaminated fresh produce is of increasing relevance to human health. However, the mechanisms of contamination of, persistence on, and transmission by fresh produce are poorly understood. We investigated the contributions of the various adhesive structures of STM to the initial event in transmission, i.e., binding to the plant surface. A reductionist system was used that allowed experimentally controlled surface expression of individual adhesive structures and analyses of the contribution to binding to leave surfaces of corn salad under laboratory conditions. The model system allowed the determination of the relative contributions of fimbrial and nonfimbrial adhesins, the type 3 secretion systems, the O antigen of lipopolysaccharide, the flagella, and chemotaxis of STM to binding to corn salad leaves. Based on these data, future work could reveal the mechanism of binding and the relevance of interaction under agricultural conditions.
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Schierstaedt J, Grosch R, Schikora A. Agricultural production systems can serve as reservoir for human pathogens. FEMS Microbiol Lett 2020; 366:5715908. [PMID: 31981360 DOI: 10.1093/femsle/fnaa016] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 01/21/2020] [Indexed: 12/31/2022] Open
Abstract
Food-borne diseases are a threat to human health and can cause severe economic losses. Nowadays, in a growing and increasingly interconnected world, food-borne diseases need to be dealt with in a global manner. In order to tackle this issue, it is essential to consider all possible entry routes of human pathogens into the production chain. Besides the post-harvest handling of the fresh produce itself, also the prevention of contamination in livestock and agricultural soils are of particular importance. While the monitoring of human pathogens and intervening measures are relatively easy to apply in livestock and post-harvest, the investigation of the prevention strategies in crop fields is a challenging task. Furthermore, crop fields are interconnected with livestock via fertilizers and feed; therefore, a poor hygiene management can cause cross-contamination. In this review, we highlight the possible contamination of crop plants by bacterial human pathogens via the rhizosphere, their interaction with the plant and possible intervention strategies. Furthermore, we discuss critical issues and questions that are still open.
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Affiliation(s)
- Jasper Schierstaedt
- Plant-Microbe Systems, Leibniz Institute of Vegetable and Ornamental Crops, 14979 Großbeeren, Germany
| | - Rita Grosch
- Plant-Microbe Systems, Leibniz Institute of Vegetable and Ornamental Crops, 14979 Großbeeren, Germany
| | - Adam Schikora
- Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, 38104 Braunschweig, Germany
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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: 29] [Impact Index Per Article: 7.3] [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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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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Zarkani AA, Schierstaedt J, Becker M, Krumwiede J, Grimm M, Grosch R, Jechalke S, Schikora A. Salmonella adapts to plants and their environment during colonization of tomatoes. FEMS Microbiol Ecol 2019; 95:5582605. [DOI: 10.1093/femsec/fiz152] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 10/01/2019] [Indexed: 02/04/2023] Open
Abstract
ABSTRACT
Humans and animals are considered typical hosts for Salmonella, however, also plants can be colonized. Tomatoes were linked to salmonellosis outbreaks already on several occasions. The aim of this study was, therefore, to establish a comprehensive view on the interaction between Salmonella enterica and tomatoes, and to test the hypothesis that colonization of plants is an interactive process. We assessed the persistence of Salmonella in agricultural soil, the colonization pattern in and on tomatoes, as well as the reciprocal responses of tomatoes to different Salmonella strains and Salmonella to root exudates and tomato-related media. This study revealed that Salmonella can persist in the soil and inside the tomato plant. Additionally, we show that Salmonella strains have particular colonization pattern, although the persistence inside the plant differs between the tested strains. Furthermore, the transcriptome response of tomato showed an up-regulation of several defense-related genes. Salmonella transcriptome analysis in response to the plant-based media showed differentially regulated genes related to amino acid and fatty acid synthesis and stress response, while the response to root exudates revealed regulation of the glyoxylate cycle. Our results indicate that both organisms actively engage in the interaction and that Salmonella adapts to the plant environment.
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Affiliation(s)
- Azhar A Zarkani
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
- University of Baghdad, Department of Biotechnology, Al-Jadriya, Baghdad 10071, Iraq
| | - Jasper Schierstaedt
- Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Plant-Microbe Systems, Theodor-Echtermeyer Weg 1, Großbeeren 14979, Germany
| | - Marlies Becker
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
| | - Johannes Krumwiede
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
| | - Maja Grimm
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
| | - Rita Grosch
- Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Plant-Microbe Systems, Theodor-Echtermeyer Weg 1, Großbeeren 14979, Germany
| | - Sven Jechalke
- Justus Liebig University Giessen, Institute for Phytopathology, Heinrich-Buff-Ring 26–32 (iFZ), Giessen 35392, Germany
| | - Adam Schikora
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
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Karmakar K, Nair AV, Chandrasekharan G, Garai P, Nath U, Nataraj KN, N B P, Chakravortty D. Rhizospheric life of Salmonella requires flagella-driven motility and EPS-mediated attachment to organic matter and enables cross-kingdom invasion. FEMS Microbiol Ecol 2019; 95:fiz107. [PMID: 31271416 DOI: 10.1093/femsec/fiz107] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 07/03/2019] [Indexed: 09/19/2023] Open
Abstract
Salmonella is an established pathogen of the members of the kingdom Animalia. Reports indicate that the association of Salmonella with fresh, edible plant products occurs at the pre-harvest state, i.e. in the field. In this study, we follow the interaction of Salmonella Typhimurium with the model plant Arabidopsis thaliana to understand the process of migration in soil. Plant factors like root exudates serve as chemo-attractants. Our ex situ experiments allowed us to track Salmonella from its free-living state to the endophytic state. We found that genes encoding two-component systems and proteins producing extracellular polymeric substances are essential for Salmonella to adhere to the soil and roots. To understand the trans-kingdom flow of Salmonella, we fed the contaminated plants to mice and observed that it invades and colonizes liver and spleen. To complete the disease cycle, we re-established the infection in plant by mixing the potting mixture with the fecal matter collected from the diseased animals. Our experiments revealed a cross-kingdom invasion by the pathogen via passage through a murine intermediate, a mechanism for its persistence in the soil and invasion in a non-canonical host. These results form a basis to break the life-cycle of Salmonella before it reaches its animal host and thus reduce Salmonella contamination of food products.
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Affiliation(s)
- Kapudeep Karmakar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Abhilash Vijay Nair
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Giridhar Chandrasekharan
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
- Department of Microbiology, St. Joseph's College Autonomous, Bangalore, India
| | - Preeti Garai
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Utpal Nath
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Karaba N Nataraj
- Department of Crop Physiology, University of Agricultural Science, Bangalore, India
| | - Prakash N B
- Department of Soil Science and Agricultural Chemistry, University of Agricultural Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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Keshri J, Krouptiski Y, Abu-Fani L, Achmon Y, Bauer TS, Zarka O, Maler I, Pinto R, Sela Saldinger S. Dynamics of bacterial communities in alfalfa and mung bean sprouts during refrigerated conditions. Food Microbiol 2019; 84:103261. [PMID: 31421775 DOI: 10.1016/j.fm.2019.103261] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 06/07/2019] [Accepted: 07/05/2019] [Indexed: 02/08/2023]
Abstract
Sprouts are considered a healthy ready-to-eat food and has gained popularity in recent years. The objective of the present study was to determine the dynamics of sprouts' microbiome during cold storage to the end of their shelf-life at home. The microbiological quality of fresh alfalfa (Medicago sativa) and mung bean (Vigna radiata) sprouts from two commercial brands was tested and the number of APC ranges from 5.0 to 8.7 log CFU/g in alfalfa and 6.7 to 9.3 log CFU/g in mung bean sprouts. In the case of alfalfa, but not mung beans, there were differences in the mean numbers of APC between the two brands. The number of coliform bacteria ranges from 4.3 to 7.7 log CFU/g in alfalfa and 4.1 to 8.1 log CFU/g in mung bean sprouts. Four independent batches of sprouts were used for DNA preparation and were sampled immediately after purchase and once a week during subsequent storage in refrigerator until the end of their shelf-life. Microbial population of the sprouts was determined using next generation sequencing of 16S rRNA amplicons. Alfalfa sprouts were dominated by Pseudomonas throughout the storage time with relative abundance of >60% at 3 weeks. Fresh mung bean sprouts were dominated by both Pseudomonas and Pantoea, but Pantoea became the dominant taxa after 2 weeks of storage, with >46% of relative abundance. The bacterial communities associated with sprouts were largely dependent on the sprout type, and less dependent on the brand. The species richness and diversity declined during storage and the development of spoilage. Among the 160 genera identified on sprouts, 23 were reported to contain known spoilage-associated species and 30 genera comprise potential human pathogenic species. This study provides new insight into the microbiome dynamics of alfalfa and mung bean sprouts during cold storage.
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Affiliation(s)
- Jitendra Keshri
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel; College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA, 91766, USA
| | - Yulia Krouptiski
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Lareen Abu-Fani
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Ygal Achmon
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel; Department of Biotechnology and Food Engineering, Guangdong Technion Israel Institute of Technology, Shantou, China
| | - Tal Stern Bauer
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel; Department of Biochemistry and Food Science, Hebrew University of Jerusalem, Israel
| | - Omri Zarka
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Ilana Maler
- The Laboratory of Food Microbiology, Kimron Veterinary Institute, P.O. Box 12, Bet Dagan, 50250, Israel
| | - Riky Pinto
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel
| | - Shlomo Sela Saldinger
- Department of Food Science, Institute for Postharvest and Food Sciences, The Volcani Center, Agriculture Research Organization, Rishon-LeZion, Israel.
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Darlison J, Mieli M, Bengtsson T, Hartmann R, Mogren L, Vågsholm I, Karlsson M, Alsanius BW. Plant species affects establishment of Escherichia coli O157:H7 gfp+ on leafy vegetables. J Appl Microbiol 2019; 127:292-305. [PMID: 31054164 DOI: 10.1111/jam.14299] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/18/2019] [Accepted: 04/29/2019] [Indexed: 01/25/2023]
Abstract
AIMS Greenhouse trials were conducted with different cultivars of baby leaf spinach, rocket and Swiss chard and inoculation of Escherichia coli O157:H7 gfp+, to determine whether plant species and cultivar have an impact on the establishment of this strain. METHODS AND RESULTS Three cultivars each of spinach, rocket and Swiss chard were spray inoculated with E. coli O157:H7 gfp+ at doses of log 7 CFU per ml. Due to the different lengths of growing period spinach and Swiss chard were spray inoculated three times and rocket five times, with final inoculation performed 3 days prior to harvest. After a growing period of 26-33 days, E. coli O157:H7 gfp+ was recovered from the leaf surface in mean populations between log 1 and 6 CFU per gram. The lowest occurrence of E. coli O157:H7 gfp+ was found on rocket leaves and the highest on spinach. There was no significant difference in the establishment of E. coli O157:H7 gfp+ between cultivars, but there were differences between plant species. Indigenous phyllosphere bacteria were pure cultured and identified with 16S rRNA gene sequencing. CONCLUSIONS Despite the same high inoculation dose of E. coli O157:H7 gfp+ on leaves, the establishment rate differed between plant species. However, plant cultivar did not affect establishment. Pantoea agglomerans dominated the identified bacterial isolates. SIGNIFICANCE AND IMPACT OF THE STUDY As previous studies are inconclusive on choice of model plant species and cultivar, we studied whether plant species or cultivar determines the fate of E. coli O157:H7 gfp+ on leafy vegetables. The findings indicate that plant species is a key determinant in the establishment of E. coli O157:H7 gfp+.
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Affiliation(s)
- J Darlison
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - M Mieli
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - T Bengtsson
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - R Hartmann
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden.,Department of Horticultural Production Systems, Wilhelm Leibniz University, Hannover, Germany
| | - L Mogren
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - I Vågsholm
- Department of Biomedical Sciences and Veterinary Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - M Karlsson
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - B W Alsanius
- Department of Biosystems and Technology, Microbial Horticulture Laboratory, Swedish University of Agricultural Sciences, Alnarp, Sweden
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Merget B, Forbes KJ, Brennan F, McAteer S, Shepherd T, Strachan NJC, Holden NJ. Influence of Plant Species, Tissue Type, and Temperature on the Capacity of Shiga-Toxigenic Escherichia coli To Colonize, Grow, and Be Internalized by Plants. Appl Environ Microbiol 2019; 85:e00123-19. [PMID: 30902860 PMCID: PMC6532046 DOI: 10.1128/aem.00123-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 03/20/2019] [Indexed: 12/21/2022] Open
Abstract
Contamination of fresh produce with pathogenic Escherichia coli, including Shiga-toxigenic E. coli (STEC), represents a serious risk to human health. Colonization is governed by multiple bacterial and plant factors that can impact the probability and suitability of bacterial growth. Thus, we aimed to determine whether the growth potential of STEC for plants associated with foodborne outbreaks (two leafy vegetables and two sprouted seed species) is predictive of the colonization of living plants, as assessed from growth kinetics and biofilm formation in plant extracts. The fitness of STEC isolates was compared to that of environmental E. coli isolates at temperatures relevant to plant growth. Growth kinetics in plant extracts varied in a plant-dependent and isolate-dependent manner for all isolates, with spinach leaf lysates supporting the highest rates of growth. Spinach extracts also supported the highest levels of biofilm formation. Saccharides were identified to be the major driver of bacterial growth, although no single metabolite could be correlated with growth kinetics. The highest level of in planta colonization occurred on alfalfa sprouts, though internalization was 10 times more prevalent in the leafy vegetables than in sprouted seeds. Marked differences in in planta growth meant that the growth potential of STEC could be inferred only for sprouted seeds. In contrast, biofilm formation in extracts related to spinach colonization. Overall, the capacity of E. coli to colonize, grow, and be internalized within plants or plant-derived matrices was influenced by the isolate type, plant species, plant tissue type, and temperature, complicating any straightforward relationship between in vitro and in planta behaviors.IMPORTANCE Fresh produce is an important vehicle for STEC transmission, and experimental evidence shows that STEC can colonize plants as secondary hosts, but differences in the capacity to colonize occur between different plant species and tissues. Therefore, an understanding of the impact that these plant factors have on the ability of STEC to grow and establish is required for food safety considerations and risk assessment. Here, we determined whether growth and the ability of STEC to form biofilms in plant extracts could be related to specific plant metabolites or could predict the ability of the bacteria to colonize living plants. Growth rates for sprouted seeds (alfalfa and fenugreek) but not those for leafy vegetables (lettuce and spinach) exhibited a positive relationship between plant extracts and living plants. Therefore, the detailed variations at the level of the bacterial isolate, plant species, and tissue type all need to be considered in risk assessment.
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Affiliation(s)
- Bernhard Merget
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
- School of Biological Sciences, The University of Aberdeen, Aberdeen, United Kingdom
| | - Ken J Forbes
- School of Medicine and Dentistry, The University of Aberdeen, Aberdeen, United Kingdom
| | - Fiona Brennan
- Teagasc, Department of Environment, Soils and Land-Use, Wexford, Republic of Ireland
| | - Sean McAteer
- Roslin Institute & R(D)SVS, The University of Edinburgh, Edinburgh, United Kingdom
| | - Tom Shepherd
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
| | - Norval J C Strachan
- School of Biological Sciences, The University of Aberdeen, Aberdeen, United Kingdom
| | - Nicola J Holden
- Cell and Molecular Sciences, The James Hutton Institute, Dundee, United Kingdom
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Jechalke S, Schierstaedt J, Becker M, Flemer B, Grosch R, Smalla K, Schikora A. Salmonella Establishment in Agricultural Soil and Colonization of Crop Plants Depend on Soil Type and Plant Species. Front Microbiol 2019; 10:967. [PMID: 31156568 PMCID: PMC6529577 DOI: 10.3389/fmicb.2019.00967] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/16/2019] [Indexed: 12/20/2022] Open
Abstract
Human pathogenic bacteria, such as Salmonella enterica, are able to colonize crop plants. So far, not much is known about biotic and abiotic factors influencing this colonization in field soil. This understanding, however, is imperative for the provision of safe fresh produce to the consumer. In this study, we investigated the effects of soil type, organic fertilization, plant species and the way of Salmonella entry into the plant production system, on the survival of S. enterica in soil as well as the colonization of plants. The selected S. enterica serovar Typhimurium strain 14028s, S. Typhimurium strain LT2 and S. Senftenberg were able to persist in soil for several weeks. Salmonella's persistence in soil was prolonged in loamy, if compared to sandy soil, and when applied together with organic fertilizer. The leaves of lettuce and corn salad were colonized by S. enterica providing evidence for internalization from the soil via the root. Colonization rates were affected by soil type, plant species and S. enterica strain. Overall, S. enterica was detected in leaves of 0.5-0.9% of the plants, while lettuce was more frequently colonized than corn salad. Plants grown in sandy soil were more often colonized than plants grown in loamy soil. After spray inoculation, S. enterica could be detected on and in leaves for several weeks by cultivation-depending methods, confirmed by confocal microscopy using GFP-labeled S. Typhimurium 14028s. On the one hand, transcriptome data from S. Typhimurium 14028s assessed in response to lettuce medium or lettuce root exudates showed an upregulation of genes associated with biofilm formation and virulence. On the other hand, lettuce inoculated with S. Typhimurium 14028s showed a strong upregulation of genes associated with plant immune response and genes related to stress response. In summary, these results showed that organic fertilizers can increase the persistence of Salmonella in soil and that soil type and plant species play a crucial role in the interactions between human pathogens and crop plants. This understanding is therefore a starting point for new strategies to provide safe food for the consumer.
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Affiliation(s)
- Sven Jechalke
- Institute for Phytopathology, Justus Liebig University Giessen, Gießen, Germany
| | - Jasper Schierstaedt
- Leibniz Institute of Vegetable and Ornamental Crops, Plant-Microbe Systems, Großbeeren, Germany
| | - Marlies Becker
- Federal Research Centre for Cultivated Plants, Julius Kühn-Institut (JKI), Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
| | - Burkhardt Flemer
- Leibniz Institute of Vegetable and Ornamental Crops, Plant-Microbe Systems, Großbeeren, Germany
| | - Rita Grosch
- Leibniz Institute of Vegetable and Ornamental Crops, Plant-Microbe Systems, Großbeeren, Germany
| | - Kornelia Smalla
- Federal Research Centre for Cultivated Plants, Julius Kühn-Institut (JKI), Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
| | - Adam Schikora
- Federal Research Centre for Cultivated Plants, Julius Kühn-Institut (JKI), Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
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45
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van Bruggen AHC, Goss EM, Havelaar A, van Diepeningen AD, Finckh MR, Morris JG. One Health - Cycling of diverse microbial communities as a connecting force for soil, plant, animal, human and ecosystem health. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 664:927-937. [PMID: 30769316 DOI: 10.1016/j.scitotenv.2019.02.091] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/05/2019] [Accepted: 02/05/2019] [Indexed: 05/06/2023]
Abstract
The One Health concept proposes that there is a connection between human, animal and environmental health. Plants and their health are not explicitly included. In this review, we broaden the One Health concept to include soil, plant, animal and ecosystem health. We argue that the health conditions of all organisms in an ecosystem are interconnected through the cycling of subsets of microbial communities from the environment (in particular the soil) to plants, animals and humans, and back into the environment. After an introduction on health concepts, we present examples of community stability and resilience, diversity and interconnectedness as affected by pollutants, and integrity of nutrient cycles and energy flows. Next, we explain our concept of microbial cycling in relation to ecosystem health, and end with examples of plant and animal disease outbreaks in relation to microbial community composition and diversity. We conclude that we need a better understanding of the role of interconnected microbiomes in promoting plant and animal health and possible ways to stimulate a healthy, diverse microbiome throughout human-dominated ecosystems. We suggest that it is essential to maintain ecosystem and soil health through diversification of plant communities and oligotrophication of managed ecosystems.
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Affiliation(s)
- Ariena H C van Bruggen
- Department of Plant Pathology, University of Florida, Gainesville FL32611, USA; Emerging Pathogens Institute, University of Florida, Gainesville FL32611, USA.
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville FL32611, USA; Emerging Pathogens Institute, University of Florida, Gainesville FL32611, USA
| | - Arie Havelaar
- Emerging Pathogens Institute, University of Florida, Gainesville FL32611, USA; Department of Animal Science, University of Florida, Gainesville FL32611, USA
| | - Anne D van Diepeningen
- Business Unit Biointeractions and Plant Health, Wageningen UR, 6708 PB Wageningen, the Netherlands
| | - Maria R Finckh
- Faculty of Organic Agricultural Sciences, Ecological Plant Protection, University of Kassel, 37213 Witzenhausen, Germany
| | - J Glenn Morris
- Emerging Pathogens Institute, University of Florida, Gainesville FL32611, USA; Department of Medicine, School of Medicine, University of Florida, Gainesville FL32611, USA
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Kroupitski Y, Gollop R, Belausov E, Pinto R, Sela Saldinger S. Salmonella enterica Growth Conditions Influence Lettuce Leaf Internalization. Front Microbiol 2019; 10:639. [PMID: 31057491 PMCID: PMC6482241 DOI: 10.3389/fmicb.2019.00639] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 03/13/2019] [Indexed: 11/21/2022] Open
Abstract
Human pathogens on plants (HPOP) have evolved complex interactions with their plant host. Stomatal internalization is one such mode of interaction, where bacteria are attracted to stomata and penetrate into the substomatal cavity by a process mediated by chemotaxis. Internalization enables HPOP to evade the hostile environment of the leaf surface and find a protected, nutrient-rich niche within the leaf. Numerous studies have documented attachment and entry of the foodborne pathogens, Salmonella enterica and Escherichia coli into stomata. Internalization, however, varies considerably among different pathogens and in different plants, and both bacterial and plant’s factors were reported to influence HPOP attachment and internalization. Here we have studied the effect of laboratory growth conditions, on the internalization of Salmonella enterica serovar Typhimurium (STm) into lettuce leaf. We have further tested the potential involvement of universal stress-proteins in leaf internalization. We found that STm grown in Luria Bertani broth devoid of NaCl (LBNS), or in diluted LB (0.5×LB) internalized lettuce leaf better (62 ± 5% and 59 ± 7%, respectively) compared to bacteria grown in LB (15 ± 7%). Growth under non-aerated conditions also enhanced STm internalization compared to growth under aerated conditions. Growth temperature of 25 and 37°C did not affect STm internalization, however, growth at 42°C, significantly augmented leaf internalization. Since, the tested growth conditions represent moderate stresses, we further investigated the involvement of five universal-stress genes in STm leaf internalization following growth in LBNS medium. Knockout mutations in ydaA, yecG, ybdQ, and uspAB, but not in ynaF, significantly reduced STm internalization compared to the wild-type (wt) strain, without affecting bacterial attachment and motility. Transduction of the mutations back to the parent strain confirmed the linkage between the mutations and the internalization phenotype. These findings support a specific role of the universal-stress genes in leaf internalization. The present study highlights the complexity of bacterial internalization process and may provide partial explanation for the variable, sometimes-contrasting results reported in the literature regarding stomatal internalization by HPOP. Characterization of the regulatory networks that mediate the involvement of usp genes and the tested growth factors in STm internalization should contribute to our understanding of human pathogens-plant interactions.
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Affiliation(s)
- Yulia Kroupitski
- Microbial Food-Safety Research Unit, Department of Food Science, Agricultural Research Organization, The Volcani Center, Rishon LeZion, Israel
| | - Rachel Gollop
- Microbial Food-Safety Research Unit, Department of Food Science, Agricultural Research Organization, The Volcani Center, Rishon LeZion, Israel
| | - Eduard Belausov
- Confocal Microscopy Unit, Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Rishon LeZion, Israel
| | - Riky Pinto
- Microbial Food-Safety Research Unit, Department of Food Science, Agricultural Research Organization, The Volcani Center, Rishon LeZion, Israel
| | - Shlomo Sela Saldinger
- Microbial Food-Safety Research Unit, Department of Food Science, Agricultural Research Organization, The Volcani Center, Rishon LeZion, Israel
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Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation. HORTICULTURAE 2019. [DOI: 10.3390/horticulturae5010025] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh produce industry. Here, we will focus on hydroponic leafy vegetable production (including lettuce, spinach, microgreens, and herbs), which can be categorized into six types: (1) nutrient film technique (NFT), (2) deep water raft culture (DWC), (3) flood and drain, (4) continuous drip systems, (5) the wick method, and (6) aeroponics. The first five are the most commonly used in the production of leafy vegetables. Each of these systems may confer different risks and advantages in the production of leafy vegetables. This review aims to (i) address the differences in current hydroponic system designs with respect to human pathogen internalization risk, and (ii) identify the preventive control points for reducing risks related to pathogen contamination in leafy greens and related fresh produce products.
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48
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Erickson MC, Liao JY, Payton AS, Cook PW, Den Bakker HC, Bautista J, Pérez JCD. Pre-harvest internalization and surface survival of Salmonella and Escherichia coli O157:H7 sprayed onto different lettuce cultivars under field and growth chamber conditions. Int J Food Microbiol 2019; 291:197-204. [PMID: 30551016 DOI: 10.1016/j.ijfoodmicro.2018.12.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/15/2018] [Accepted: 12/03/2018] [Indexed: 10/27/2022]
Abstract
Plant genotype has been advocated to have an important role in the fate of enteric pathogens residing in lettuce foliage. This study was therefore undertaken under the premise that different pathogen responses could occur in lettuce cultivars with cultivar selection being one of several hurdles in an overall strategy for controlling foodborne pathogens on field-grown produce. Up to eight lettuce cultivars ('Gabriella', 'Green Star', 'Muir', 'New Red Fire', 'Coastal Star', 'Starfighter', 'Tropicana', and 'Two Star') were examined in these experiments in which the plants were subjected to spray contamination of their foliage with pathogens. In an experiment that addressed internalization of Salmonella, cultivar was determined to be a significant variable (P < 0.05) with 'Gabriella' and 'Muir' being the least and most likely to exhibit internalization of this pathogen, respectively. Furthermore, antimicrobials (total phenols and antioxidant capacity chemicals) could be part of the plant's defenses to resist internalization as there was an inverse relationship between the prevalence of internalization at 1 h and the levels of these antimicrobials (r = -0.75 to -0.80, P = 0.0312 to 0.0165). Internalized cells appeared to be transient residents in that across all cultivars, plants sampled 1 h after being sprayed were 3.5 times more likely to be positive for Salmonella than plants analyzed 24 h after spraying (95% CI from 1.5 to 8.2, P = 0.0035). The fate of surface-resident Salmonella and Escherichia coli O157:H7 was addressed in subsequent growth chamber and field experiments. In the growth chamber study, no effect of cultivar was manifested on the fate of either pathogen when plants were sampled up to 12 days after spray contamination of their foliage. However, in the field study, five days after spraying the plants, Salmonella contamination was significantly affected by cultivar (P < 0.05) and the following order of prevalence of contamination was observed: 'Muir' < 'Gabriella' < 'Green Star' = 'New Red Fire' < 'Coastal Star'. Nine days after spray contamination of plants in the field, no effect of cultivar was exhibited due primarily to the low prevalence of contamination observed for Salmonella (8 of 300 plant samples positive by enrichment culture) and E. coli O157 (4 of 300 plant samples positive by enrichment culture). Given the narrow window of time during which cultivar differences were documented, it is unlikely that cultivar selection could serve as a viable option for reducing the microbiological risk associated with lettuce.
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Affiliation(s)
- Marilyn C Erickson
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA.
| | - Jye-Yin Liao
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA
| | - Alison S Payton
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA
| | - Peter W Cook
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA
| | - Henk C Den Bakker
- Center for Food Safety, Department of Food Science and Technology, University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA
| | - Jesus Bautista
- Department of Horticulture, University of Georgia, 2360 Rainwater Rd., Tifton, GA 31793-5766, USA
| | - Juan Carlos Díaz Pérez
- Department of Horticulture, University of Georgia, 2360 Rainwater Rd., Tifton, GA 31793-5766, USA
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49
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Wheatley RM, Poole PS. Mechanisms of bacterial attachment to roots. FEMS Microbiol Rev 2018; 42:448-461. [PMID: 29672765 DOI: 10.1093/femsre/fuy014] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 04/14/2018] [Indexed: 11/13/2022] Open
Abstract
The attachment of bacteria to roots constitutes the first physical step in many plant-microbe interactions. These interactions exert both positive and negative influences on agricultural systems depending on whether a growth-promoting, symbiotic or pathogenic relationship transpires. A common biphasic mechanism of root attachment exists across agriculturally important microbial species, including Rhizobium, Agrobacterium, Pseudomonas, Azospirillum and Salmonella. Attachment studies have revealed how plant-microbe interactions develop, and how to manipulate these relationships for agricultural benefit. Here, we review our current understanding of the molecular mechanisms governing plant-microbe root attachment and draw together a common biphasic model.
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Affiliation(s)
- Rachel M Wheatley
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
| | - Philip S Poole
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK
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50
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Karmakar K, Nath U, Nataraja KN, Chakravortty D. Root mediated uptake of Salmonella is different from phyto-pathogen and associated with the colonization of edible organs. BMC PLANT BIOLOGY 2018; 18:344. [PMID: 30537948 PMCID: PMC6290541 DOI: 10.1186/s12870-018-1578-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 11/29/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Pre-harvest contamination of fruits and vegetables by Salmonella in fields is one of the causes of food-borne outbreaks. Natural openings like stomata, hydathodes and fruit cracks are known to serve as entry points. While there are reports indicating that Salmonella colonize and enter root through lateral root emerging area, further investigations regarding how the accessibility of Salmonella to lateral root is different from phyto-pathogenic bacteria, the efficacy of lateral root to facilitate entry have remained unexplored. In this study we attempted to investigate the lateral root mediated entry of Salmonella, and to bridge this gap in knowledge. RESULTS Unlike phytopathogens, Salmonella cannot utilize cellulose as the sole carbon source. This negates the fact of active entry by degrading plant cellulose and pectin. Endophytic Salmonella colonization showed a high correlation with number of lateral roots. When given equal opportunity to colonize the plants with high or low lateral roots, Salmonella internalization was found higher in the plants with more lateral roots. However, the epiphytic colonization in both these plants remained unaltered. To understand the ecological significance, we induced lateral root production by increasing soil salinity which made the plants susceptible to Salmonella invasion and the plants showed higher Salmonella burden in the aerial organs. CONCLUSION Salmonella, being unable to degrade plant cell wall material relies heavily on natural openings. Therefore, its invasion is highly dependent on the number of lateral roots which provides an entry point because of the epidermis remodeling. Thus, when number of lateral root was enhanced by increasing the soil salinity, plants became susceptible to Salmonella invasion in roots and its transmission to aerial organs.
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Affiliation(s)
- Kapudeep Karmakar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 India
| | - Utpal Nath
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 India
| | - Karaba N. Nataraja
- Department of Crop Physiology, University of Agricultural Science, GKVK, Bangalore, 560065 India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012 India
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, 560012 India
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