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Holden ER, Abi Assaf J, Al-Khanaq H, Vimont N, Webber MA, Trampari E. Identification of pathways required for Salmonella to colonize alfalfa using TraDIS- Xpress. Appl Environ Microbiol 2024; 90:e0013924. [PMID: 38904400 PMCID: PMC11267905 DOI: 10.1128/aem.00139-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/23/2024] [Indexed: 06/22/2024] Open
Abstract
Enteropathogenic bacteria, such as Salmonella, have been linked to numerous fresh produce outbreaks, posing a significant public health threat. The ability of Salmonella to persist on fresh produce for extended periods is partly attributed to its capacity to form biofilms, which pose a challenge to food decontamination and can increase pathogenic bacterial load in the food chain. Preventing Salmonella colonization of food products and food processing environments is crucial for reducing the incidence of foodborne outbreaks. Understanding the mechanisms of establishment on fresh produce will inform the development of decontamination approaches. We used Transposon-Directed Insertion site Sequencing (TraDIS-Xpress) to investigate the mechanisms used by Salmonella enterica serovar Typhimurium to colonize and establish on fresh produce over time. We established an alfalfa colonization model and compared the findings to those obtained from glass surfaces. Our research identified distinct mechanisms required for Salmonella establishment on alfalfa compared with glass surfaces over time. These include the type III secretion system (sirC), Fe-S cluster assembly (iscA), curcumin degradation (curA), and copper tolerance (cueR). Shared pathways across surfaces included NADH hydrogenase synthesis (nuoA and nuoB), fimbrial regulation (fimA and fimZ), stress response (rpoS), LPS O-antigen synthesis (rfbJ), iron acquisition (ybaN), and ethanolamine utilization (eutT and eutQ). Notably, flagellum biosynthesis differentially impacted the colonization of biotic and abiotic environments over time. Understanding the genetic underpinnings of Salmonella establishment on both biotic and abiotic surfaces over time offers valuable insights that can inform the development of targeted antibacterial therapeutics, ultimately enhancing food safety throughout the food processing chain. IMPORTANCE Salmonella is the second most costly foodborne illness in the United Kingdom, accounting for £0.2 billion annually, with numerous outbreaks linked to fresh produce, such as leafy greens, cucumbers, tomatoes, and alfalfa sprouts. The ability of Salmonella to colonize and establish itself in fresh produce poses a significant challenge, hindering decontamination efforts and increasing the risk of illness. Understanding the key mechanisms of Salmonella to colonize plants over time is key to finding new ways to prevent and control contamination of fresh produce. This study identified genes and pathways important for Salmonella colonization of alfalfa and compared those with colonization of glass using a genome-wide screen. Genes with roles in flagellum biosynthesis, lipopolysaccharide production, and stringent response regulation varied in their significance between plants and glass. This work deepens our understanding of the requirements for plant colonization by Salmonella, revealing how gene essentiality changes over time and in different environments. This knowledge is key to developing effective strategies to reduce the risk of foodborne disease.
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Affiliation(s)
- Emma R. Holden
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
| | - Justin Abi Assaf
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
| | - Haider Al-Khanaq
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
| | - Noemie Vimont
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
| | - Mark A. Webber
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Eleftheria Trampari
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
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Gutiérrez-Pacheco MM, Torres-Moreno H, Flores-Lopez ML, Velázquez Guadarrama N, Ayala-Zavala JF, Ortega-Ramírez LA, López-Romero JC. Mechanisms and Applications of Citral's Antimicrobial Properties in Food Preservation and Pharmaceuticals Formulations. Antibiotics (Basel) 2023; 12:1608. [PMID: 37998810 PMCID: PMC10668791 DOI: 10.3390/antibiotics12111608] [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: 09/30/2023] [Revised: 11/01/2023] [Accepted: 11/04/2023] [Indexed: 11/25/2023] Open
Abstract
Citral is a monoterpene constituted by two isomers known as neral and geranial. It is present in different plant sources and recognized as safe (GRAS) by the Food and Drug Administration (FDA). In recent years, investigations have demonstrated that this compound exhibited several biological activities, such as antibacterial, antifungal, antibiofilm, antiparasitic, antiproliferative, anti-inflammatory, and antioxidant properties, by in vitro and in vivo assays. Additionally, when incorporated into different food matrices, citral can reduce the microbial load of pathogenic microorganisms and extend the shelf life. This compound has acceptable drug-likeness properties and does not present any violations of Lipinski's rules, which could be used for drug development. The above shows that citral could be a compound of interest for developing food additives to extend the shelf life of animal and vegetable origin foods and develop pharmaceutical products.
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Affiliation(s)
| | - Heriberto Torres-Moreno
- Departamento de Ciencias Químico-Biológicas y Agropecuarias, Universidad de Sonora, H. Caborca 83600, Sonora, Mexico;
| | - María Liliana Flores-Lopez
- Centro de Investigación e Innovación Científica y Tecnológica, Universidad Autónoma de Coahuila, Saltillo 25070, Coahuila, Mexico;
| | - Norma Velázquez Guadarrama
- Laboratorio de Investigación en Enfermedades Infecciosas, Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico;
| | - J. Fernando Ayala-Zavala
- Coordinación de Tecnología de Alimentos de Origen Vegetal, Centro de Investigación en Alimentación y Desarrollo, A. C. Carretera Gustavo Astiazarán Rosas No. 46, Colonia la Victoria, Hermosillo 83304, Sonora, Mexico;
| | - Luis Alberto Ortega-Ramírez
- Departamento de Ciencias de la Salud, Universidad Estatal de Sonora, San Luis Río Colorado 83430, Sonora, Mexico;
| | - Julio César López-Romero
- Departamento de Ciencias Químico-Biológicas y Agropecuarias, Universidad de Sonora, H. Caborca 83600, Sonora, Mexico;
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3
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The conjugative transfer of plasmid-mediated mobile colistin resistance gene, mcr-1, to Escherichia coli O157:H7 and Escherichia coli O104:H4 in nutrient broth and in mung bean sprouts. Food Microbiol 2023; 111:104188. [PMID: 36681389 DOI: 10.1016/j.fm.2022.104188] [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: 08/28/2022] [Revised: 11/10/2022] [Accepted: 11/15/2022] [Indexed: 11/27/2022]
Abstract
The emergence of mobile colistin resistant gene (mcr-1) in Enterobacteriaceae has become a global public health concern. Dissemination of the mcr-1 gene through conjugation of bacteria associated with food may occur. This research investigated the transfer frequency of the mcr-1 gene among Escherichia coli in liquid media and during growth of mung bean sprouts. The donor strain E. coli NCTC 13846 (mcr-1 positive) and recipient strains of E. coli O157:H7 and E. coli O104:H4 were used. Mating experiments in vitro were conducted at 4, 25, and 37 °C for up to 36 h. The in vivo mating experiments (growing sprouts) were conducted in a sprout growth chamber with irrigation of 1 min/h over 6 days following inoculation of mung bean seeds with the donor and a recipient. The highest transfer frequencies in TSB media, 2.86E-07 and 3.24E-07, occurred at 37 °C after mating for 24 h for E. coli O104:H4 and E. coli O157:H7, respectively. Transconjugants were not detected in liquid media at 4 °C. Moreover, transfer frequency (5.68E-05 per recipient) of mcr-1 was greater during mung bean sprout growth for E. coli O104:H4 compared to E. coli O157:H7 (1.02E-05 per recipient) Day 3 to Day 6. This study indicates that the transfer of antibiotic resistant gene(s) among bacteria during mung bean sprout production may facilitate the spread of antibiotic resistant bacteria in the environment and to humans.
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Fessia A, Sartori M, García D, Fernández L, Ponzio R, Barros G, Nesci A. In vitro studies of biofilm-forming Bacillus strains, biocontrol agents isolated from the maize phyllosphere. Biofilm 2022; 4:100097. [PMID: 36504526 PMCID: PMC9731887 DOI: 10.1016/j.bioflm.2022.100097] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/08/2022] [Accepted: 11/18/2022] [Indexed: 12/12/2022] Open
Abstract
We aimed to assess how biofilm formation by three Bacillus isolates was affected by changes in temperature, water potential, growth media, time, and the combinations between these factors. The strains had been selected as potential biological control agents (BCAs) in earlier studies, and they were identified as B. subtilis and B. velezensis spp. through 16 rRNA sequencing and MALDI-TOF MS. Maize leaves (ML) were used as one of the growth media, since they made it possible to simulate the nutrient content in the maize phyllosphere, from which the bacteria were originally isolated. The strains were able to form biofilm both in ML and biofilm-inducing MSgg after 24, 48, and 72 h. Biofilm development in the form of pellicles and architecturally complex colonies varied morphologically from one strain to another and depended on the conditions mentioned above. In all cases, colonies and pellicles were less complex when both temperature and water potential were lower. Scanning electron microscopy (SEM) revealed that changing levels of complexity in pellicles were correlated with those in colonies. Statistical analyses found that the quantification of biofilm produced by the isolates was influenced by all the conditions tested. In terms of motility (which may contribute to biofilm formation), swimming and swarming were possible for all strains in 0.3 and 0.7% agar, respectively. A more in-depth understanding of how abiotic factors influence biofilm formation can contribute to a more effective use of these biocontrol strains against pathogens in the maize phyllosphere.
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Affiliation(s)
- Aluminé Fessia
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina,Corresponding author. Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina.
| | - Melina Sartori
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Daiana García
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Luciana Fernández
- Departamento de Física, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, CONICET, X5804BYA, Río Cuarto, Argentina,Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Rodrigo Ponzio
- Departamento de Física, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, CONICET, X5804BYA, Río Cuarto, Argentina,Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Germán Barros
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Andrea Nesci
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
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Rivero W, Wang Q, Salvi D. Impact of plasma-activated water washing on the microbial inactivation, color, and electrolyte leakage of alfalfa sprouts, broccoli sprouts, and clover sprouts. INNOV FOOD SCI EMERG 2022. [DOI: 10.1016/j.ifset.2022.103123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Fessia A, Barra P, Barros G, Nesci A. Could Bacillus biofilms enhance the effectivity of biocontrol strategies in the phyllosphere? J Appl Microbiol 2022; 133:2148-2166. [PMID: 35476896 DOI: 10.1111/jam.15596] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/13/2022] [Accepted: 04/21/2022] [Indexed: 11/30/2022]
Abstract
Maize (Zea mays L.), a major crop in Argentina and a staple food around the world, is affected by the emergence and re-emergence of foliar diseases. Agrochemicals are the main control strategy nowadays, but they can cause resistance in insects and microbial pathogens and have negative effects on the environment and human health. An emerging alternative is the use of living organisms, i.e. microbial biocontrol agents, to suppress plant pathogen populations. This is a risk-free approach when the organisms acting as biocontrol agents come from the same ecosystem as the foliar pathogens they are meant to antagonize. Some epiphytic microorganisms may form biofilm by becoming aggregated and attached to a surface, as is the case of spore-forming bacteria from the genus Bacillus. Their ability to sporulate and their tolerance to long storage periods make them a frequently used biocontrol agent. Moreover, the biofilm that they create protects them against different abiotic and biotic factors and helps them to acquire nutrients, which ensures their survival on the plants they protect. This review analyzes the interactions that the phyllosphere-inhabiting Bacillus genus establishes with its environment through biofilm, and how this lifestyle could serve to design effective biological control strategies.
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Affiliation(s)
- Aluminé Fessia
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ruta Nacional 36, Km 601, X5804ZAB Río Cuarto, Córdoba, Argentina
| | - Paula Barra
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ruta Nacional 36, Km 601, X5804ZAB Río Cuarto, Córdoba, Argentina
| | - Germán Barros
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ruta Nacional 36, Km 601, X5804ZAB Río Cuarto, Córdoba, Argentina
| | - Andrea Nesci
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ruta Nacional 36, Km 601, X5804ZAB Río Cuarto, Córdoba, Argentina
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7
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Lin Y, Alstrup M, Pang JKY, Maróti G, Er-Rafik M, Tourasse N, Økstad OA, Kovács ÁT. Adaptation of Bacillus thuringiensis to Plant Colonization Affects Differentiation and Toxicity. mSystems 2021; 6:e0086421. [PMID: 34636664 PMCID: PMC8510532 DOI: 10.1128/msystems.00864-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/27/2021] [Indexed: 01/11/2023] Open
Abstract
The Bacillus cereus group (Bacillus cereus sensu lato) has a diverse ecology, including various species that are vertebrate or invertebrate pathogens. Few isolates from the B. cereus group have however been demonstrated to benefit plant growth. Therefore, it is crucial to explore how bacterial development and pathogenesis evolve during plant colonization. Herein, we investigated Bacillus thuringiensis (Cry-) adaptation to the colonization of Arabidopsis thaliana roots and monitored changes in cellular differentiation in experimentally evolved isolates. Isolates from two populations displayed improved iterative ecesis on roots and increased virulence against insect larvae. Molecular dissection and recreation of a causative mutation revealed the importance of a nonsense mutation in the rho transcription terminator gene. Transcriptome analysis revealed how Rho impacts various B. thuringiensis genes involved in carbohydrate metabolism and virulence. Our work suggests that evolved multicellular aggregates have a fitness advantage over single cells when colonizing plants, creating a trade-off between swimming and multicellularity in evolved lineages, in addition to unrelated alterations in pathogenicity. IMPORTANCE Biologicals-based plant protection relies on the use of safe microbial strains. During application of biologicals to the rhizosphere, microbes adapt to the niche, including genetic mutations shaping the physiology of the cells. Here, the experimental evolution of Bacillus thuringiensis lacking the insecticide crystal toxins was examined on the plant root to reveal how adaptation shapes the differentiation of this bacterium. Interestingly, evolution of certain lineages led to increased hemolysis and insect larva pathogenesis in B. thuringiensis driven by transcriptional rewiring. Further, our detailed study reveals how inactivation of the transcription termination protein Rho promotes aggregation on the plant root in addition to altered differentiation and pathogenesis in B. thuringiensis.
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Affiliation(s)
- Yicen Lin
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Monica Alstrup
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Janet Ka Yan Pang
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Gergely Maróti
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Mériem Er-Rafik
- National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Lyngby, Denmark
| | - Nicolas Tourasse
- Université Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, Bordeaux, France
| | - Ole Andreas Økstad
- Centre for Integrative Microbial Evolution, University of Oslo, Oslo, Norway
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Ákos T. Kovács
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
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Figueiredo CM, Malvezzi Karwowski MS, da Silva Ramos RCP, de Oliveira NS, Peña LC, Carneiro E, Freitas de Macedo RE, Rosa EAR. Bacteriophages as tools for biofilm biocontrol in different fields. BIOFOULING 2021; 37:689-709. [PMID: 34304662 DOI: 10.1080/08927014.2021.1955866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 07/07/2021] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
Microbial biofilms are difficult to control due to the limited accessibility that antimicrobial drugs and chemicals have to the entrapped inner cells. The extracellular matrix, binds water, contributes to altered cell physiology within biofilms and act as a barrier for most antiproliferative molecules. Thus, new strategies need to be developed to overcome biofilm vitality. In this review, based on 223 documents, the advantages, recommendations, and limitations of using bacteriophages as 'biofilm predators' are presented. The plausibility of using phages (bacteriophages and mycoviruses) to control biofilms grown in different environments is also discussed. The topics covered here include recent historical experiences in biofilm control/eradication using phages in medicine, dentistry, veterinary, and food industries, the pros and cons of their use, and the development of microbial resistance/immunity to such viruses.
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Affiliation(s)
| | | | | | | | - Lorena Caroline Peña
- Xenobiotics Research Unit, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil
| | - Everdan Carneiro
- Graduate Program in Dentistry, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil
| | | | - Edvaldo Antonio Ribeiro Rosa
- Graduate Program in Dentistry, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil
- Graduate Program in Animal Sciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil
- Xenobiotics Research Unit, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil
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Endogenous Metabolites Released by Sanitized Sprouting Alfalfa Seed Inhibit the Growth of Salmonella enterica. mSystems 2021; 6:6/1/e00898-20. [PMID: 33563786 PMCID: PMC7883538 DOI: 10.1128/msystems.00898-20] [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] [Indexed: 11/20/2022] Open
Abstract
Warm, humid, and nutrient-rich conditions that are used to produce sprouts encourage Salmonella enterica to proliferate. However, many disparate sanitation methods exist, and there is currently no single treatment that can guarantee pathogen-free seeds. Sprouts are the leading cause of foodborne disease outbreaks globally, mainly because the specialized conditions required to germinate seed sprouts for human consumption contribute to an environment that allows pathogenic bacteria to flourish. To reduce risk of illness, current food safety guidelines in the United States and Canada recommend hypochlorite treatment for seed sanitation. However, many growers and consumers have become wary of the impact of hypochlorite on human health and the environment and are actively seeking less caustic approaches. Here, we evaluated the effects of both the traditional hypochlorite treatment and a milder alternative on nontyphoidal Salmonella enterica colonization of germinating alfalfa seed. Moreover, we explored three biological factors as potential contributors for inhibition of S. enterica growth: colonization by indigenous bacteria, seed composition changes, and seed metabolite release. In this experimental setting, we found that a combinatorial treatment of heat, peroxide, and acetic acid was as effective as hypochlorite for inhibiting S. enterica growth. Notably, we pinpointed N-acetyl-spermidine as an endogenous metabolite exuded by treated seeds that strongly inhibits S. enterica growth. In doing so, we both elucidated one of the mechanisms of chemical sanitation and highlighted a potential seed-derived mode of antimicrobial treatment that may apply to modernized food safety protocols. IMPORTANCE Warm, humid, and nutrient-rich conditions that are used to produce sprouts encourage Salmonella enterica to proliferate. However, many disparate sanitation methods exist, and there is currently no single treatment that can guarantee pathogen-free seeds. Here, we compared the ability of traditional hypochlorite treatment against a combinatorial treatment of heat, peroxide, and vinegar (HPA) commonly used in organic farming practices to inhibit S. enterica colonization and growth during alfalfa germination and found HPA to be at least as effective. Furthermore, we explored seed-based changes following sanitization treatments using metabolomics and identified polyamines as strong inhibitors of Salmonella growth on germinating alfalfa. Our findings enable a better understanding of host-pathogen interactions in sprout microbial communities and promote in-depth, evidence-based research in seed sprout safety.
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Wong CW, Delaquis P, Goodridge L, Lévesque RC, Fong K, Wang S. Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail. Curr Res Food Sci 2020; 2:25-32. [PMID: 32914108 PMCID: PMC7473338 DOI: 10.1016/j.crfs.2019.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Salmonella enterica (S. enterica) is a causative agent of multiple outbreaks of foodborne illness associated with fresh produce, including pre-cut melon and leafy vegetables. Current industrial antimicrobial interventions have been shown to reduce microbial populations by <90%. Consequently, bacteriophages have been suggested as an alternative to chemical sanitizers. Seven S. enterica strains from four serovars (105 CFU/mL) were separately inoculated onto excised pieces of Romaine lettuce leaf and cantaloupe flesh treated with a five-strain bacteriophage cocktail 24 h before S. enterica inoculation. S. enterica, total aerobic populations and water activity were measured immediately after inoculation and after 1 and 2 days of incubation at 8 °C. The efficacy of the bacteriophage cocktail varied between strains. Populations of S. enterica Enteritidis strain S3, S. Javiana S203, S. Javiana S200 were reduced by > 3 log CFU/g and S. Newport S2 by 1 log CFU/g on both lettuce and cantaloupe tissues at all sampling times. In contrast, populations of strains S. Thompson S193 and S194 were reduced by 2 log CFU/g on day 0 on lettuce, but were not significantly different (P > 0.05) from the controls thereafter, S. Newport S195 populations were reduced on lettuce by 1 log CFU/g on day 0 and no reductions were found on cantaloupe tissue. Both aerobic populations and water activity were higher on cantaloupe than on lettuce. The water activity of lettuce decreased significantly (P < 0.05) from 0.845 ± 0.027 on day 0-0.494 ± 0.022 on day 1, but that of cantaloupe remained between 0.977 and 0.993 from day 0-2. The results of this study showed that bacteriophages can reduce S. enterica populations on lettuce and cantaloupe tissues but that the magnitude of the effect was strain-dependent.
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Affiliation(s)
- Catherine W.Y. Wong
- Department of Food Science, University of British Columbia, 2205 East Mall, Vancouver, BC, V6R 1Z4, Canada
| | - Pascal Delaquis
- Agriculture and Agri-Food Canada, 4200 Highway 97, Summerland, BC, V0H 1Z0, Canada
| | - Lawrence Goodridge
- Department of Food Science and Agricultural Chemistry, McGill University, Montréal, QC, Canada
| | - Roger C. Lévesque
- Institute for Integrative and Systems Biology, Université Laval, Québec City, QC, Canada
| | - Karen Fong
- Department of Food Science, University of British Columbia, 2205 East Mall, Vancouver, BC, V6R 1Z4, Canada
| | - Siyun Wang
- Department of Food Science, University of British Columbia, 2205 East Mall, Vancouver, BC, V6R 1Z4, Canada
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Carvacrol Loaded Solid Lipid Nanoparticles of Propylene Glycol Monopalmitate and Glyceryl Monostearate: Preparation, Characterization, and Synergistic Antimicrobial Activity. NANOMATERIALS 2019; 9:nano9081162. [PMID: 31416170 PMCID: PMC6723752 DOI: 10.3390/nano9081162] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 02/07/2023]
Abstract
To develop solid lipid nanoparticles (SLNs) with stable lipid matrix structures for the delivery of bioactive compounds, a new class of SLNs was studied using propylene glycol monopalmitate (PGMP) and glyceryl monostearate (GMS) mixtures and carvacrol as a model lipophilic antimicrobial. Stable SLNs were fabricated at PGMP:GMS mass ratios of 2:1 and 1:1, and the carvacrol loading was up to 30% of lipids with >98% encapsulation efficiency and absence of visual instability. Fluorescence spectra and release profiles indicated the carvacrol was successfully encapsulated and homogeneously distributed within the SLNs. SLNs fabricated with equal masses of PGMP and GMS had better stability of carvacrol during storage and higher sphericity than those with a ratio of 2:1 and were much more effective than free carvacrol against Escherichia coli O157:H7 and Staphylococcus aureus. These findings demonstrated the potential applications of the studied SLNs in delivering lipophilic bioactive compounds in food and other products.
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12
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Khelissa SO, Abdallah M, Jama C, Barras A, Chihib NE. Comparative Study on the Impact of Growth Conditions on the Physiology and the Virulence of Pseudomonas aeruginosa Biofilm and Planktonic Cells. J Food Prot 2019; 82:1357-1363. [PMID: 31313963 DOI: 10.4315/0362-028x.jfp-18-565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of the present work was to study and compare the effect of growth temperature (20, 30, and 37°C) and surface type (stainless steel and polycarbonate) on the production of virulence factors, such as proteases and siderophores, and the risk of surface contamination associated with Pseudomonas aeruginosa biofilm and planktonic cells. The increase of growth temperature from 20 to 37°C increased (approximately twofold) the electronegative charge and the hydrophobicity of the P. aeruginosa biofilm cell surface. P. aeruginosa biofilm cell adhesion to stainless steel and polycarbonate was 5- and 1.5-fold higher than their planktonic counterparts at 20 and 30°C, respectively. The increase of growth temperature from 20 to 37°C increased the production of proteases (twofold) and siderophores (twofold) and the cytotoxicity (up to 30-fold) against the HeLa cell line in the supernatants of P. aeruginosa planktonic and biofilm cultures. This study also highlighted that biofilm and planktonic P. aeruginosa cells exhibited distinct physiological properties with respect to the production of virulence factors and the cytotoxicity against the Hela cell line. Therefore, effective disinfection procedures should be adapted to inactivate bacteria detached from biofilms.
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Affiliation(s)
- Simon Oussama Khelissa
- 1 Universite´ de Lille, Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA), École Nationale Supérieure de Chimie de Lille (ENSCL), Unités Mixtes de Recherche (UMR) 8207-Unité Matériaux et Transformations (UMET)-Processus aux Interfaces et Hygiène des Matériaux (PIHM), 59000 Lille, France
| | - Marwan Abdallah
- 1 Universite´ de Lille, Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA), École Nationale Supérieure de Chimie de Lille (ENSCL), Unités Mixtes de Recherche (UMR) 8207-Unité Matériaux et Transformations (UMET)-Processus aux Interfaces et Hygiène des Matériaux (PIHM), 59000 Lille, France
| | - Charafeddine Jama
- 2 Universite´ de Lille, CNRS, INRA, ENSCL, UMR 8207-UMET-ISP (Inge´nierie des Syste`me Polyme`res), 59000 Lille, France
| | - Alexandre Barras
- 3 Université de Lille, CNRS, Centrale Lille, Institut Supérieur de l'Électronique et du Numérique (ISEN), Université de Valenciennes, UMR 8520-Institut d' Électronique, de Microélectronique et de Nanotechnologie (IEMN), 59000 Lille, France
| | - Nour-Eddine Chihib
- 1 Universite´ de Lille, Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA), École Nationale Supérieure de Chimie de Lille (ENSCL), Unités Mixtes de Recherche (UMR) 8207-Unité Matériaux et Transformations (UMET)-Processus aux Interfaces et Hygiène des Matériaux (PIHM), 59000 Lille, France
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13
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Miceli A, Settanni L. Influence of agronomic practices and pre-harvest conditions on the attachment and development of Listeria monocytogenes in vegetables. ANN MICROBIOL 2019. [DOI: 10.1007/s13213-019-1435-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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14
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Mathew EN, Muyyarikkandy MS, Kuttappan D, Amalaradjou MA. Attachment of Salmonella enterica on Mangoes and Survival Under Conditions Simulating Commercial Mango Packing House and Importer Facility. Front Microbiol 2018; 9:1519. [PMID: 30042752 PMCID: PMC6048225 DOI: 10.3389/fmicb.2018.01519] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/19/2018] [Indexed: 11/13/2022] Open
Abstract
Consumption of raw mangoes has led to multiple Salmonella-associated foodborne outbreaks in the United States. Although several studies have investigated the epiphytic fitness of Salmonella on fresh produce, there is sparse information available on the survival of Salmonella on mangoes under commercial handling and storage conditions. Hence, the objective of the study was to evaluate the survival of Salmonella on mangoes under ambient conditions simulating the mango packing house and importer facility. Further, the ability of the pathogen to adhere and attach on to the mango fructoplane was also investigated. For the attachment assays, mango skin sections were inoculated with fifty microliters of S. Newport suspension (6.5 log CFU/skin section) and minimum time required for adhesion and attachment were recorded. With the survival assays, unwaxed mangoes were spot inoculated with the Salmonella cocktail to establish approximately 4 and 6.5 log CFU/mango. The fruits were then subjected to different storage regimens simulating fruit unloading, waxing, and storage at the packing house and ripening and storage at the importer facility. Results of our study reveal that Salmonella was able to adhere on to the fructoplane immediately after contact. Further, formation of attachment structures was seen as early as 2 min following inoculation. With the survival assays, irrespective of the inoculum levels, no significant increase or decrease in pathogen population was observed when fruit were stored either at ambient (29-32°C and RH 85-95%, for 48 h), ripening (20-22°C and RH 90-95% for 9 days) or refrigerated storage (10-15°C and 85-95% for 24-48 h) conditions. Therefore, once contaminated, mangoes could serve as potential vehicles in the transmission of Salmonella along the post-harvest environment. Hence development and adoption of effective food safety measures are warranted to promote the microbiological safety of mangoes.
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15
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Fu Y, Deering AJ, Bhunia AK, Yao Y. Pathogen biofilm formation on cantaloupe surface and its impact on the antibacterial effect of lauroyl arginate ethyl. Food Microbiol 2017; 64:139-144. [DOI: 10.1016/j.fm.2016.12.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 12/27/2016] [Accepted: 12/27/2016] [Indexed: 10/20/2022]
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16
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Sadekuzzaman M, Yang S, Mizan MFR, Ha SD. Reduction ofEscherichia coliO157:H7 in Biofilms Using Bacteriophage BPECO 19. J Food Sci 2017; 82:1433-1442. [DOI: 10.1111/1750-3841.13729] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 03/30/2017] [Accepted: 04/04/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Mohammad Sadekuzzaman
- School of Food Science and Technology; Chung-Ang Univ.; 72-1 Nae-Ri, Daedeok-Myun Anseong Gyunggido 456-756 South Korea
- Dept. of Livestock Services; People's Republic of Bangladesh
| | - Sungdae Yang
- School of Food Science and Technology; Chung-Ang Univ.; 72-1 Nae-Ri, Daedeok-Myun Anseong Gyunggido 456-756 South Korea
| | - Md. Furkanur Rahaman Mizan
- School of Food Science and Technology; Chung-Ang Univ.; 72-1 Nae-Ri, Daedeok-Myun Anseong Gyunggido 456-756 South Korea
| | - Sang-Do Ha
- School of Food Science and Technology; Chung-Ang Univ.; 72-1 Nae-Ri, Daedeok-Myun Anseong Gyunggido 456-756 South Korea
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17
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Kim YJ, Kim HS, Kim KY, Chon JW, Kim DH, Seo KH. High Occurrence Rate and Contamination Level of Bacillus cereus in Organic Vegetables on Sale in Retail Markets. Foodborne Pathog Dis 2016; 13:656-660. [PMID: 27992273 DOI: 10.1089/fpd.2016.2163] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Organic foods have risen in popularity recently. However, the increased risk of bacterial contamination of organic foods has not been fully evaluated. In this study, 100 samples each of organic and conventional fresh vegetables (55 lettuce samples and 45 sprout samples) sold in South Korea were analyzed for aerobic bacteria, coliforms, Escherichia coli, and Bacillus cereus. Although the aerobic bacteria and coliform counts were not significantly different between the two farming types (p > 0.05), the occurrence rate of B. cereus was higher in organically cultivated vegetables compared with those grown conventionally (70% vs. 30%, respectively). The mean contamination level of B. cereus-positive organic samples was also significantly higher (1.86 log colony-forming unit [CFU]/g vs. 0.69 log CFU/g, respectively) (p < 0.05). In addition, six samples of organic vegetables were found to be contaminated with B. cereus at over 4 log CFU/g categorized as unsatisfactory according to Health Protection Agency guideline. The relatively higher occurrence rate of B. cereus in organic vegetables emphasizes the importance of implementing control measures in organic vegetable production and postharvest processing to reduce the risk of food poisoning.
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Affiliation(s)
- Young-Ji Kim
- Center for One Health, College of Veterinary Medicine, Konkuk University , Seoul, South Korea
| | - Hong-Seok Kim
- Center for One Health, College of Veterinary Medicine, Konkuk University , Seoul, South Korea
| | - Kwang-Yeop Kim
- Center for One Health, College of Veterinary Medicine, Konkuk University , Seoul, South Korea
| | - Jung-Whan Chon
- Center for One Health, College of Veterinary Medicine, Konkuk University , Seoul, South Korea
| | - Dong-Hyeon Kim
- Center for One Health, College of Veterinary Medicine, Konkuk University , Seoul, South Korea
| | - Kun-Ho Seo
- Center for One Health, College of Veterinary Medicine, Konkuk University , Seoul, South Korea
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18
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Faour-Klingbeil D, Kuri V, Todd EC. The influence of pre-wash chopping and storage conditions of parsley on the efficacy of disinfection against S. Typhimurium. Food Control 2016. [DOI: 10.1016/j.foodcont.2016.01.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2022]
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19
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Srinandan CS, Elango M, Gnanadhas DP, Chakravortty D. Infiltration of Matrix-Non-producers Weakens the Salmonella Biofilm and Impairs Its Antimicrobial Tolerance and Pathogenicity. Front Microbiol 2015; 6:1468. [PMID: 26779121 PMCID: PMC4688346 DOI: 10.3389/fmicb.2015.01468] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/07/2015] [Indexed: 01/22/2023] Open
Abstract
Bacterial biofilms display a collective lifestyle, wherein the cells secrete extracellular polymeric substances (EPS) that helps in adhesion, aggregation, stability, and to protect the bacteria from antimicrobials. We asked whether the EPS could act as a public good for the biofilm and observed that infiltration of cells that do not produce matrix components weakened the biofilm of Salmonella enterica serovar Typhimurium. EPS production was costly for the producing cells, as indicated by a significant reduction in the fitness of wild type (WT) cells during competitive planktonic growth relative to the non-producers. Infiltration frequency of non-producers in the biofilm showed a concomitant decrease in overall productivity. It was apparent in the confocal images that the non-producing cells benefit from the EPS produced by the Wild Type (WT) to stay in the biofilm. The biofilm containing non-producing cells were more significantly susceptible to sodium hypochlorite and ciprofloxacin treatment than the WT biofilm. Biofilm infiltrated with non-producers delayed the pathogenesis, as tested in a murine model. The cell types were spatially assorted, with non-producers being edged out in the biofilm. However, cellulose was found to act as a barrier to keep the non-producers away from the WT microcolony. Our results show that the infiltration of non-cooperating cell types can substantially weaken the biofilm making it vulnerable to antibacterials and delay their pathogenesis. Cellulose, a component of EPS, was shown to play a pivotal role of acting as the main public good, and to edge-out the non-producers away from the cooperating microcolony.
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Affiliation(s)
- Chakravarthy S Srinandan
- Department of Microbiology and Cell Biology, Indian Institute of ScienceBangalore, India; Biofilm Biology Lab, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA UniversityThanjavur, India
| | - Monalisha Elango
- Department of Microbiology and Cell Biology, Indian Institute of Science Bangalore, India
| | - Divya P Gnanadhas
- Department of Microbiology and Cell Biology, Indian Institute of ScienceBangalore, India; Department of Aerospace Engineering, Indian Institute of ScienceBangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of ScienceBangalore, India; Centre for Biosystems Science and Engineering, Indian Institute of ScienceBangalore, India
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20
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Chavatte N, Lambrecht E, Van Damme I, Sabbe K, Houf K. Abundance, diversity and community composition of free-living protozoa on vegetable sprouts. Food Microbiol 2015; 55:55-63. [PMID: 26742616 DOI: 10.1016/j.fm.2015.11.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 11/09/2015] [Accepted: 11/20/2015] [Indexed: 01/20/2023]
Abstract
Interactions with free-living protozoa (FLP) have been implicated in the persistence of pathogenic bacteria on food products. In order to assess the potential involvement of FLP in this contamination, detailed knowledge on their occurrence, abundance and diversity on food products is required. In the present study, enrichment and cultivation methods were used to inventory and quantify FLP on eight types of commercial vegetable sprouts (alfalfa, beetroot, cress, green pea, leek, mung bean, red cabbage and rosabi). In parallel, total aerobic bacteria and Escherichia coli counts were performed. The vegetable sprouts harbored diverse communities of FLP, with Tetrahymena (ciliate), Bodo saltans and cercomonads (flagellates), and Acanthamoeba and Vannella (amoebae) as the dominant taxa. Protozoan community composition and abundance significantly differed between the sprout types. Beetroot harbored the most abundant and diverse FLP communities, with many unique species such as Korotnevella sp., Vannella sp., Chilodonella sp., Podophrya sp. and Sphaerophrya sp. In contrast, mung bean sprouts were species-poor and had low FLP numbers. Sampling month and company had no significant influence, suggesting that seasonal and local factors are of minor importance. Likewise, no significant relationship between protozoan community composition and bacterial load was observed.
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Affiliation(s)
- N Chavatte
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
| | - E Lambrecht
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
| | - I Van Damme
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
| | - K Sabbe
- Department of Biology, Faculty of Sciences, Ghent University, Krijgslaan 281, 9000 Ghent, Belgium.
| | - K Houf
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
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21
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Uyttendaele M, Jaykus LA, Amoah P, Chiodini A, Cunliffe D, Jacxsens L, Holvoet K, Korsten L, Lau M, McClure P, Medema G, Sampers I, Rao Jasti P. Microbial Hazards in Irrigation Water: Standards, Norms, and Testing to Manage Use of Water in Fresh Produce Primary Production. Compr Rev Food Sci Food Saf 2015. [DOI: 10.1111/1541-4337.12133] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Lee-Ann Jaykus
- Dept. of Food, Bioprocessing and Nutrition Sciences; North Carolina State Univ; U.S.A
| | | | - Alessandro Chiodini
- ILSI Europe, Intl. Life Sciences Inst; European Branch; 83 Ave. E. Mounier, B6, B-1200 Brussels Belgium
| | - David Cunliffe
- Dept. of Health; Public Health; P.O. Box 6, Rundle Mall 5000 South Australia
| | | | - Kevin Holvoet
- Dept. Food Safety & Food Quality; Ghent Univ; Ghent Belgium
| | - Lise Korsten
- Dept. of Plant and Crop Sciences; Univ. of Pretoria; 0002 Pretoria South Africa
| | - Mathew Lau
- School of Chemical & Life Sciences; Nanyang Polytechnic; Singapore
| | - Peter McClure
- Mondelez Intl., Bayerwaldstrasse 8; 81737 München; Germany
| | - Gertjan Medema
- KWR, Watercycle Research Inst; Delft Univ. of Technology; Postbus 1072 3430 BB Nieuwegein The Netherlands
| | - Imca Sampers
- Dept. of Industrial Biological Sciences; Ghent Univ. Campus Kortrijk; Kortrijk Belgium
| | - Pratima Rao Jasti
- ILSI Europe, Intl. Life Sciences Inst; European Branch; 83 Ave. E. Mounier, B6, B-1200 Brussels Belgium
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22
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Mathews SL, Smith RB, Matthysse AG. A comparison of the retention of pathogenic Escherichia coli O157 by sprouts, leaves and fruits. Microb Biotechnol 2014; 7:570-9. [PMID: 25351040 PMCID: PMC4265075 DOI: 10.1111/1751-7915.12165] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 07/31/2014] [Accepted: 08/11/2014] [Indexed: 11/30/2022] Open
Abstract
The retention (binding to or association with the plant) of Escherichia coli by cut leaves and fruits after vigorous water washing was compared with that by sprouts. Retention by fruits and leaves was similar but differed from retention by sprouts in rate, effect of wounding and requirement for poly-β,1-6-N-acetyl-D-glucosamine. Escherichia coli was retained by cut ends of lettuce leaves within 5 min while more than 1 h was required for retention by the intact epidermis of leaves and fruits, and more than 1 day for sprouts. Retention after 5 min at the cut leaf edge was specific for E. coli and was not shown by the plant-associated bacteria Agrobacterium tumefaciens and Sinorhizobium meliloti. Escherichia coli was retained by lettuce, spinach, alfalfa, bean, tomato, Arabidopsis thaliana, cucumber, and pepper leaves and fruits faster than by sprouts. Wounding of leaves and fruits but not sprouts increased bacterial retention. Mutations in the exopolysaccharide synthesis genes yhjN and wcaD reduced the numbers of bacteria retained. PgaC mutants were retained by cut leaves and fruits but not by sprouts. There was no significant difference in the retention of an O157 and a K12 strain by fruits or leaves. However, retention by sprouts of O157 strains was significantly greater than K12 strains. These findings suggest that there are differences in the mechanisms of E coli retention among sprouts, and leaves and fruits.
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Affiliation(s)
| | - Rachel B Smith
- Department of Biology, University of North CarolinaChapel Hill, NC, 27599-3280, USA
| | - Ann G Matthysse
- Department of Biology, University of North CarolinaChapel Hill, NC, 27599-3280, USA
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23
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Jahid IK, Ha SD. The Paradox of Mixed-Species Biofilms in the Context of Food Safety. Compr Rev Food Sci Food Saf 2014. [DOI: 10.1111/1541-4337.12087] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iqbal Kabir Jahid
- School of Food Science and Technology; Chung-Ang Univ; 72-1 Nae-Ri, Daedeok-Myun Anseong-Si Gyeonggi-do 456-756 South Korea
- Dept. of Microbiology; Jessore Univ. of Science and Technology; Jessore-7408 Bangladesh
| | - Sang-Do Ha
- School of Food Science and Technology; Chung-Ang Univ; 72-1 Nae-Ri, Daedeok-Myun Anseong-Si Gyeonggi-do 456-756 South Korea
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24
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Lee NY, Kim SW, Ha SD. Synergistic effects of ultrasound and sodium hypochlorite (NaOCl) on reducing Listeria monocytogenes ATCC19118 in broth, stainless steel, and iceberg lettuce. Foodborne Pathog Dis 2014; 11:581-7. [PMID: 24927252 DOI: 10.1089/fpd.2013.1722] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study was performed in order to determine whether a combined treatment of ultrasound and sodium hypochlorite (NaOCl) is more effective than individual treatment on reducing Listeria monocytogenes ATCC19118 on stainless steel and iceberg lettuce. The bactericidal effect of ultrasound and NaOCl was investigated in tryptic soy broth (TSB), on stainless steel and iceberg lettuce. Various concentrations of NaOCl (50, 100, 150, and 200 ppm) were tested along with various ultrasound treatment times (5, 20, 40, 60, 80, and 100 min). The combined treatment of ultrasound and NaOCl resulted in greater bacterial reductions than either treatment alone, without causing any significant changes in lettuce texture. The synergistic values of combined ultrasound and NaOCl treatments in TSB, on stainless steel, and on iceberg lettuce were 0.01-0.99 log10 colony-forming units (CFU)/mL, 0.01-0.62 log 10 CFU/g, and 0.12-1.66 log10 CFU/g, respectively. These results suggest that the combination of ultrasound and NaOCl was more effective than each treatment against Listeria monocytogenes, and that this combination can effectively sanitize fresh products such as iceberg lettuce.
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Affiliation(s)
- Na-Young Lee
- School of Food Science and Technology, Chung-Ang University , Gyunggido, Korea
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25
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Effect of the surfactant tween 80 on the detachment and dispersal of Salmonella enterica serovar Thompson single cells and aggregates from cilantro leaves as revealed by image analysis. Appl Environ Microbiol 2014; 80:5037-42. [PMID: 24907336 DOI: 10.1128/aem.00795-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica has the ability to form biofilms and large aggregates on produce surfaces, including on cilantro leaves. Aggregates of S. enterica serovar Thompson that remained attached to cilantro leaves after rigorous washing and that were present free or bound to dislodged leaf tissue in the wash suspension were observed by confocal microscopy. Measurement of S. Thompson population sizes in the leaf washes by plate counts failed to show an effect of 0.05% Tween 80 on the removal of the pathogen from cilantro leaves 2 and 6 days after inoculation. On the contrary, digital image analysis of micrographs of single cells and aggregates of green fluorescent protein (GFP)-S. Thompson present in cilantro leaf washes revealed that single cells represented 13.7% of the cell assemblages in leaf washes containing Tween 80, versus 9.3% in those without the surfactant. Moreover, Tween 80 decreased the percentage of the total S. Thompson cell population located in aggregates equal to or larger than 64 cells from 9.8% to 4.4% (P < 0.05). Regression analysis of the frequency distribution of aggregate size in leaf washes with and without Tween 80 showed that the surfactant promoted the dispersal of cells from large aggregates into smaller ones and into single cells (P < 0.05). Our study underlines the importance of investigating bacterial behavior at the scale of single cells in order to uncover trends undetectable at the population level by bacterial plate counts. Such an approach may provide valuable information to devise strategies aimed at enhancing the efficacy of produce sanitization treatments.
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26
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Martínez-Vaz BM, Fink RC, Diez-Gonzalez F, Sadowsky MJ. Enteric pathogen-plant interactions: molecular connections leading to colonization and growth and implications for food safety. Microbes Environ 2014; 29:123-35. [PMID: 24859308 PMCID: PMC4103518 DOI: 10.1264/jsme2.me13139] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/19/2014] [Indexed: 11/12/2022] Open
Abstract
Leafy green vegetables have been identified as a source of foodborne illnesses worldwide over the past decade. Human enteric pathogens, such as Escherichia coli O157:H7 and Salmonella, have been implicated in numerous food poisoning outbreaks associated with the consumption of fresh produce. An understanding of the mechanisms responsible for the establishment of pathogenic bacteria in or on vegetable plants is critical for understanding and ameliorating this problem as well as ensuring the safety of our food supply. While previous studies have described the growth and survival of enteric pathogens in the environment and also the risk factors associated with the contamination of vegetables, the molecular events involved in the colonization of fresh produce by enteric pathogens are just beginning to be elucidated. This review summarizes recent findings on the interactions of several bacterial pathogens with leafy green vegetables. Changes in gene expression linked to the bacterial attachment and colonization of plant structures are discussed in light of their relevance to plant-microbe interactions. We propose a mechanism for the establishment and association of enteric pathogens with plants and discuss potential strategies to address the problem of foodborne illness linked to the consumption of leafy green vegetables.
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Affiliation(s)
| | - Ryan C. Fink
- Department of Food Science and Nutrition, University of Minnesota, St Paul, MN 55108, USA
| | | | - Michael J. Sadowsky
- Biotechnology Institute, University of Minnesota, St Paul, MN 55108, USA
- Department of Soil, Water and Climate, University of Minnesota, St Paul, MN 55108, USA
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27
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Schwarz K, Sidhu J, Pritchard D, Li Y, Toze S. Decay of Salmonella enterica
,Escherichia coli
and bacteriophage MS2 on the phyllosphere and stored grains of wheat (Triticum aestivum
). Lett Appl Microbiol 2013; 58:16-24. [DOI: 10.1111/lam.12149] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/05/2013] [Accepted: 08/20/2013] [Indexed: 11/26/2022]
Affiliation(s)
- K. Schwarz
- Department of Environment and Agriculture; Curtin University; Northam WA Australia
| | - J.P.S. Sidhu
- Land and Water; CSIRO; EcoSciences Precinct; Brisbane QLD Australia
| | - D. Pritchard
- Department of Environment and Agriculture; Curtin University; Northam WA Australia
| | - Y. Li
- Animal, Food and Health Sciences; CSIRO; Queensland Biosciences Precinct; Brisbane QLD Australia
| | - S. Toze
- Land and Water; CSIRO; EcoSciences Precinct; Brisbane QLD Australia
- School of Population Health; University of Queensland; Brisbane QLD Australia
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Goodburn C, Wallace CA. The microbiological efficacy of decontamination methodologies for fresh produce: A review. Food Control 2013. [DOI: 10.1016/j.foodcont.2012.12.012] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Context factors affecting design and operation of food safety management systems in the fresh produce chain. Trends Food Sci Technol 2013. [DOI: 10.1016/j.tifs.2013.06.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Cerna-Cortes JF, Gómez-Aldapa CA, Rangel-Vargas E, Ramírez-Cruz E, Castro-Rosas J. Presence of indicator bacteria, Salmonella and diarrheagenic Escherichia coli pathotypes on mung bean sprouts from public markets in Pachuca, Mexico. Food Control 2013. [DOI: 10.1016/j.foodcont.2012.10.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Yang Y, Meier F, Ann Lo J, Yuan W, Lee Pei Sze V, Chung HJ, Yuk HG. Overview of Recent Events in the Microbiological Safety of Sprouts and New Intervention Technologies. Compr Rev Food Sci Food Saf 2013. [DOI: 10.1111/1541-4337.12010] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Fabienne Meier
- Food Science & Technology Programme; Dept. of Chemistry; National Univ. of Singapore; 3 Science Drive 3; Singapore; 117543
| | - Jerilyn Ann Lo
- Food Science & Technology Programme; Dept. of Chemistry; National Univ. of Singapore; 3 Science Drive 3; Singapore; 117543
| | - Wenqian Yuan
- Food Science & Technology Programme; Dept. of Chemistry; National Univ. of Singapore; 3 Science Drive 3; Singapore; 117543
| | - Valarie Lee Pei Sze
- Food Science & Technology Programme; Dept. of Chemistry; National Univ. of Singapore; 3 Science Drive 3; Singapore; 117543
| | - Hyun-Jung Chung
- Dept. of Food and Nutrition; Inha Univ.; Incheon 402-751; Korea
| | - Hyun-Gyun Yuk
- Food Science & Technology Programme; Dept. of Chemistry; National Univ. of Singapore; 3 Science Drive 3; Singapore; 117543
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Fletcher J, Leach JE, Eversole K, Tauxe R. Human pathogens on plants: designing a multidisciplinary strategy for research. PHYTOPATHOLOGY 2013; 103:306-315. [PMID: 23406434 DOI: 10.1094/phyto-09-12-0236-ia] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent efforts to address concerns about microbial contamination of food plants and resulting foodborne illness have prompted new collaboration and interactions between the scientific communities of plant pathology and food safety. This article provides perspectives from scientists of both disciplines and presents selected research results and concepts that highlight existing and possible future synergisms for audiences of both disciplines. Plant pathology is a complex discipline that encompasses studies of the dissemination, colonization, and infection of plants by microbes such as bacteria, viruses, fungi, and oomycetes. Plant pathologists study plant diseases as well as host plant defense responses and disease management strategies with the goal of minimizing disease occurrences and impacts. Repeated outbreaks of human illness attributed to the contamination of fresh produce, nuts and seeds, and other plant-derived foods by human enteric pathogens such as Shiga toxin-producing Escherichia coli and Salmonella spp. have led some plant pathologists to broaden the application of their science in the past two decades, to address problems of human pathogens on plants (HPOPs). Food microbiology, which began with the study of microbes that spoil foods and those that are critical to produce food, now also focuses study on how foods become contaminated with pathogens and how this can be controlled or prevented. Thus, at the same time, public health researchers and food microbiologists have become more concerned about plant-microbe interactions before and after harvest. New collaborations are forming between members of the plant pathology and food safety communities, leading to enhanced research capacity and greater understanding of the issues for which research is needed. The two communities use somewhat different vocabularies and conceptual models. For example, traditional plant pathology concepts such as the disease triangle and the disease cycle can help to define cross-over issues that pertain also to HPOP research, and can suggest logical strategies for minimizing the risk of microbial contamination. Continued interactions and communication among these two disciplinary communities is essential and can be achieved by the creation of an interdisciplinary research coordination network. We hope that this article, an introduction to the multidisciplinary HPOP arena, will be useful to researchers in many related fields.
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Affiliation(s)
- Jacqueline Fletcher
- Department of Entomology & Plant Pathology, Oklahoma State University, Stillwater, OK, USA.
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Buchholz AL, Davidson GR, Marks BP, Todd ECD, Ryser ET. Quantitative transfer of Escherichia coli O157:H7 to equipment during small-scale production of fresh-cut leafy greens. J Food Prot 2012; 75:1184-97. [PMID: 22980000 DOI: 10.4315/0362-028x.jfp-11-489] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Postharvest contamination and subsequent spread of Escherichia coli O157:H7 can occur during shredding, conveying, fluming, and dewatering of fresh-cut leafy greens. This study quantified E. coli O157:H7 transfer from leafy greens to equipment surfaces during simulated small-scale commercial processing. Three to five batches (22.7 kg) of baby spinach, iceberg lettuce, and romaine lettuce were dip inoculated with a four-strain cocktail of avirulent, green fluorescent protein-labeled, ampicillinresistant E. coli O157:H7 to contain ∼10(6), 10(4), and 10(2) CFU/g, and then were processed after 1 h of draining at ∼23°C or 24 h of storage at 4°C. Lettuce was shredded using an Urschel TransSlicer at two different blade and belt speeds to obtain normal (5 by 5 cm) and more finely shredded (0.5 by 5 cm) lettuce. Thereafter, the lettuce was step conveyed to a flume tank and was washed and then dried using a shaker table and centrifugal dryer. Product (25-g) and water (40-ml) samples were collected at various points during processing. After processing, product contact surfaces (100 cm(2)) on the shredder (n = 14), conveyer (n = 8), flume tank (n = 11), shaker table (n = 9), and centrifugal dryer (n = 8) were sampled using one-ply composite tissues. Sample homogenates diluted in phosphate or neutralizing buffer were plated, with or without prior 0.45- m m membrane filtration, on Trypticase soy agar containing 0.6% yeast extract supplemented with 100 ppm of ampicillin to quantify green fluorescent protein-labeled E. coli O157:H7 under UV light. During leafy green processing, ∼90% of the E. coli O157:H7 inoculum transferred to the wash water. After processing, E. coli O157:H7 populations were highest on the conveyor and shredder (P<0.05), followed by the centrifugal dryer, flume tank, and shaker table, with ∼29% of the remaining product inoculum lost during centrifugal drying. Overall, less (P<0.05) of the inoculum remained on the product after centrifugally drying iceberg lettuce that was held for 1 h (8.13%) as opposed to 24 h (42.18%) before processing, with shred size not affecting the rate of E. coli O157:H7 transfer.
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Affiliation(s)
- Annemarie L Buchholz
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA
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Jahid IK, Ha SD. A review of microbial biofilms of produce: Future challenge to food safety. Food Sci Biotechnol 2012. [DOI: 10.1007/s10068-012-0041-1] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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36
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Steenackers H, Hermans K, Vanderleyden J, De Keersmaecker SC. Salmonella biofilms: An overview on occurrence, structure, regulation and eradication. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.01.038] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Choi S, Bang J, Kim H, Beuchat L, Ryu JH. Survival and colonization of Escherichia coli O157:H7 on spinach leaves as affected by inoculum level and carrier, temperature and relative humidity. J Appl Microbiol 2011; 111:1465-72. [DOI: 10.1111/j.1365-2672.2011.05175.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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39
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Wallace PK, Arey B, Mahaffee WF. Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy. Micron 2011; 42:579-85. [DOI: 10.1016/j.micron.2011.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 02/09/2011] [Accepted: 02/10/2011] [Indexed: 10/18/2022]
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40
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Ölmez H, Temur S. Effects of different sanitizing treatments on biofilms and attachment of Escherichia coli and Listeria monocytogenes on green leaf lettuce. Lebensm Wiss Technol 2010. [DOI: 10.1016/j.lwt.2010.02.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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41
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Collignon S, Korsten L. Attachment and colonization by Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium, and Staphylococcus aureus on stone fruit surfaces and Survival through a simulated commercial export chain. J Food Prot 2010; 73:1247-56. [PMID: 20615337 DOI: 10.4315/0362-028x-73.7.1247] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ability of the foodborne pathogens Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium, and Staphylococcus aureus to attach, colonize, and survive on stone fruit surfaces was investigated. Fifty microliters of bacterial suspension was spot inoculated onto the sterile intact fructoplane of whole peaches and plums. Minimum time required for initial adhesion and attachment was recorded for different surface contact times. Surface colonization patterns of the four pathogens and survival under simulated commercial export conditions also were evaluated. L. monocytogenes and Salmonella Typhimurium attached immediately to stone fruit surfaces. E. coli O157:H7 and S. aureus were visibly attached after 30 s and 1 h, respectively, of direct exposure. Holding freshly harvested stone fruit at 0.5 degrees C to simulate cold storage conditions significantly lowered the titer of E. coli O157:H7 on plums and the titers of L. monocytogenes and Salmonella Typhimurium on stone fruit. E. coli O157:H7 and L. monocytogenes at a low inoculum level and S. aureus and Salmonella Typhimurium at high and low levels did not survive the simulated export chain conditions at titers that exceeded the minimum infectious dose. However, E. coli O157:H7 and L. monocytogenes were able to survive on stone fruit surfaces when inoculated at an artificially high level. In this case, the final titer at the end of the supply chain was higher than the infectious dose. In this laboratory experiment, E. coli O157:H7, L. monocytogenes, Salmonella Typhimurium, and S. aureus at potential natural contamination levels were unable to survive simulated export conditions.
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Affiliation(s)
- Stacey Collignon
- Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria, South Africa
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42
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Niemira BA, Cooke PH. Escherichia coli O157:H7 biofilm formation on Romaine lettuce and spinach leaf surfaces reduces efficacy of irradiation and sodium hypochlorite washes. J Food Sci 2010; 75:M270-7. [PMID: 20629883 DOI: 10.1111/j.1750-3841.2010.01650.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Escherichia coli O157:H7 contamination of leafy green vegetables is an ongoing concern for consumers. Biofilm-associated pathogens are relatively resistant to chemical treatments, but little is known about their response to irradiation. Leaves of Romaine lettuce and baby spinach were dip inoculated with E. coli O157:H7 and stored at 4 degrees C for various times (0, 24, 48, 72 h) to allow biofilms to form. After each time, leaves were treated with either a 3-min wash with a sodium hypochlorite solution (0, 300, or 600 ppm) or increasing doses of irradiation (0, 0.25, 0.5, 0.75, or 1 kGy). Viable bacteria were recovered and enumerated. Chlorine washes were generally only moderately effective, and resulted in maximal reductions of 1.3 log CFU/g for baby spinach and 1.8 log CFU/g for Romaine. Increasing time in storage prior to chemical treatment had no effect on spinach, and had an inconsistent effect on 600 ppm applied to Romaine. Allowing time for formation of biofilm-like aggregations reduced the efficacy of irradiation. D(10) values (the dose required for a 1 log reduction) significantly increased with increasing storage time, up to 48 h postinoculation. From 0 h of storage, D(10) increased from 0.19 kGy to a maximum of 0.40 to 0.43 kGy for Romaine and 0.52 to 0.54 kGy for spinach. SEM showed developing biofilms on both types of leaves during storage. Bacterial colonization of the stomata was extensive on spinach, but not on Romaine. These results indicate that the protection of bacteria on the leaf surface by biofilm formation and stomatal colonization can reduce the antimicrobial efficacy of irradiation on leafy green vegetables.
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Affiliation(s)
- Brendan A Niemira
- Food Safety Intervention Technologies Research Unit, Eastern Regional Research Center, U.S. Dept. of Agriculture, Agricultural Research Service, Wyndmoor, PA 19038, USA.
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ITURRIAGA MONTSERRATH, ESCARTÍN EDUARDOF. CHANGES IN THE EFFECTIVENESS OF CHLORINE TREATMENTS DURING COLONIZATION OFSALMONELLAMONTEVIDEO ON TOMATOES. J Food Saf 2010. [DOI: 10.1111/j.1745-4565.2009.00207.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Microbial ecology of foodborne pathogens associated with produce. Curr Opin Biotechnol 2010; 21:125-30. [DOI: 10.1016/j.copbio.2010.01.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/02/2010] [Accepted: 01/16/2010] [Indexed: 11/22/2022]
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45
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Shirron N, Kisluk G, Zelikovich Y, Eivin I, Shimoni E, Yaron S. A comparative study assaying commonly used sanitizers for antimicrobial activity against indicator bacteria and a Salmonella Typhimurium strain on fresh produce. J Food Prot 2009; 72:2413-7. [PMID: 19903410 DOI: 10.4315/0362-028x-72.11.2413] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With increased concerns over failures in vegetable and fruit sanitation, evaluating the efficacy of widely approved chemicals is ever more important. The purpose of this study was to determine whether sanitation treatments are equally effective against indicator bacteria and human enteric pathogens on cucumber and parsley. We provide here an experimental overview on the efficacy of common sanitation methods, which are based on peracetic acid-hydrogen peroxide, sodium dichloroisocyanurate, and the quaternary ammonium compound didecyldimethylammonium chloride. The sanitizers were tested for their activity against natural populations of total aerobic microorganisms, enterococci, and coliforms, and against the enteric pathogen Salmonella Typhimurium ATCC 14028 (which was added artificially). Results revealed that compared with washing parsley and cucumbers with water, treatments with all three sanitizers were not effective, resulting in a maximal reduction of only 0.7 log CFU of Salmonella Typhimurium. These sanitizers were also not effective in removal of natural bacteria from parsley (maximal reduction was 0.7 log CFU). Sanitation of cucumber was more successful; peracetic acid showed the most effective result, with a reduction of 2.7 log in aerobic microorganisms compared with cucumbers washed with water. Still, removal of natural bacteria from cucumbers proved more efficient than the removal of Salmonella Typhimurium. This may create a debate about the necessity of the sanitation and its contribution to safety, because sanitation of some contaminated vegetables may result in an increased likelihood of foods that, although they are given good hygienic ratings due to low microbial counts, harbor pathogens.
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Affiliation(s)
- Natali Shirron
- Faculty of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
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Kroupitski Y, Golberg D, Belausov E, Pinto R, Swartzberg D, Granot D, Sela S. Internalization of Salmonella enterica in leaves is induced by light and involves chemotaxis and penetration through open stomata. Appl Environ Microbiol 2009; 75:6076-86. [PMID: 19648358 PMCID: PMC2753090 DOI: 10.1128/aem.01084-09] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 07/27/2009] [Indexed: 12/22/2022] Open
Abstract
Outbreaks of salmonellosis related to consumption of fresh produce have raised interest in Salmonella-plant interactions leading to plant colonization. Incubation of gfp-tagged Salmonella enterica with iceberg lettuce leaves in the light resulted in aggregation of bacteria near open stomata and invasion into the inner leaf tissue. In contrast, incubation in the dark resulted in a scattered attachment pattern and very poor stomatal internalization. Forcing stomatal opening in the dark by fusicoccin had no significant effect on Salmonella internalization. These results imply that the pathogen is attracted to nutrients produced de novo by photosynthetically active cells. Indeed, mutations affecting Salmonella motility and chemotaxis significantly inhibited bacterial internalization. These findings suggest a mechanistic account for entry of Salmonella into the plant's apoplast and imply that either Salmonella antigens are not well recognized by the stoma-based innate immunity or that this pathogen has evolved means to evade it. Internalization of leaves may provide a partial explanation for the failure of sanitizers to efficiently eradicate food-borne pathogens in leafy greens.
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Affiliation(s)
- Yulia Kroupitski
- Microbial Food Safety Research Unit, Department of Food Science, Agricultural Research Organization, The Volcani Center, Beth-Dagan 50250, Israel
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47
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Bisha B, Brehm-Stecher BF. Flow-through imaging cytometry for characterization ofSalmonellasubpopulations in alfalfa sprouts, a complex food system. Biotechnol J 2009; 4:880-7. [DOI: 10.1002/biot.200800360] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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48
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Franz E, van Bruggen AH. Ecology ofE. coliO157:H7 andSalmonella entericain the Primary Vegetable Production Chain. Crit Rev Microbiol 2008; 34:143-61. [DOI: 10.1080/10408410802357432] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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49
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Kocharunchitt C, Ross T, McNeil DL. Use of bacteriophages as biocontrol agents to control Salmonella associated with seed sprouts. Int J Food Microbiol 2008; 128:453-9. [PMID: 18996610 DOI: 10.1016/j.ijfoodmicro.2008.10.014] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 09/19/2008] [Accepted: 10/04/2008] [Indexed: 11/26/2022]
Abstract
Two Salmonella bacteriophages (SSP5 and SSP6) were isolated and characterized based on their morphology and host range, and evaluated for their potential to control Salmonella Oranienburg in vitro and on experimentally contaminated alfalfa seeds. Phages SSP5 and SSP6 were classified as members of the Myoviridae and Siphoviridae families, respectively. Both phages had a broad host range of over 65% of the 41 Salmonella strains tested. During in vitro trials, the phages resulted in incomplete lysis of Salmonella cultures, in spite of high levels of phage remaining in the system. Phage SSP5 was more effective in reducing Salmonella populations. Addition of phage SSP6 to alfalfa seeds previously contaminated with S. Oranienburg caused an approximately 1 log(10) CFU g(-1) reduction of viable Salmonella, which was achieved 3 h after phage application. Thereafter the phage had no inhibitory effect on Salmonella population growth. A second addition of the same (SSP6) or different (SSP5) phage to a Salmonella culture treated with phage SSP6, did not affect Salmonella populations. It was further shown that development of Salmonella permanently resistant to phage was not evident in either seed or in vitro challenge trials, suggesting the existence of a temporary, acquired, non-specific phage resistance phenomenon. These factors may complicate the use of phages for biocontrol.
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Affiliation(s)
- C Kocharunchitt
- Tasmanian Institute of Agricultural Research, University of Tasmania, Hobart TAS 7001, Australia.
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50
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Abstract
After harvest, vegetables are often spoiled by a wide variety of microorganisms including many bacterial and fungal species. The most common bacterial agents are Erwinia carotovora, Pseudomonas spp., Corynebacterium, Xanthomonas campestris, and lactic acid bacteria with E. carotovora being the most common, attacking virtually every vegetable type. Fungi commonly causing spoilage of fresh vegetables are Botrytis cinerea, various species of the genera Alternaria, Aspergillus, Cladosporium, Colletotrichum, Phomopsis, Fusarium, Penicillium, Phoma, Phytophthora, Pythium and Rhizopus spp., Botrytis cinerea, Ceratocystis fimbriata, Rhizoctonia solani, Sclerotinia sclerotiorum, and some mildews. A few of these organisms show a substrate preference whereas others such as Botrytis cinerea, Colletotrichum, Alternaria, Cladosporium, Phytophthora, and Rhizopus spp., affect a wide variety of vegetables causing devastating losses. Many of these agents enter the plant tissue through mechanical or chilling injuries, or after the skin barrier has been broken down by other organisms. Besides causing huge economic losses, some fungal species could produce toxic metabolites in the affected sites, constituting a potential health hazard for humans. Additionally, vegetables have often served as vehicles for pathogenic bacteria, viruses, and parasites and were implicated in many food borne illness outbreaks. In order to slow down vegetable spoilage and minimize the associated adverse health effects, great caution should be taken to follow strict hygiene, good agricultural practices (GAPs) and good manufacturing practices (GMPs) during cultivation, harvest, storage, transport, and marketing.
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Affiliation(s)
- V H Tournas
- Division of Natural Products, Food and Drug Administration, College Park, Maryland 20740, USA.
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