Assembly and Characterization of a Pathogen Strain Collection for Produce Safety Applications: Pre-growth Conditions Have a Larger Effect on Peroxyacetic Acid Tolerance Than Strain Diversity

Effective control of foodborne pathogens on produce requires science-based validation of interventions and control strategies, which typically involves challenge studies with a set of bacterial strains representing the target pathogens or appropriate surrogates. In order to facilitate these types of studies, a produce-relevant strain collection was assembled to represent strains from produce outbreaks or pre-harvest environments, including L. monocytogenes (n=11), S. enterica (n=23), shiga-toxin producing E. coli (STEC) (n=13), and possible surrogate organisms (n=8); all strains were characterized by whole genome sequencing (WGS). Strain diversity was assured by including the 10 most common S. enterica serotypes, L. monocytogenes lineages I-IV, and E. coli O157 as well as selected “non-O157” STEC serotypes. As it has previously been shown that strains and genetic lineages of a pathogen may differ in their ability to survive different stress conditions, a subset of representative strains for each “pathogen group” (e.g., Salmonella, STEC) was selected and assessed for survival of exposure to peroxyacetic acid (PAA) using strains pre-grown under different conditions including (i) low pH, (ii) high salt, (iii) reduced water activity, (iv) different growth phases, (v) minimal medium, and (vi) different temperatures (21°C, 37°C). The results showed that across the three pathogen groups pre-growth conditions had a larger effect on bacterial reduction ...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research

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This study aimed at investigating the influence of two key parameters (concentration of curcumin and illumination time) on the effects of curcumin-based photodynamic sterilization on the preservation of fresh-cut Hami melons. The results indicated that illumination with 50 μmol/L curcumin for 60 min using a blue LED lamp reduced the total aerobic microorganism count by ~1.8 log CFU/g in fresh-cut Hami melons. Besides this, the effects of photodynamic sterilization on the soluble solids content, color, water content, firmness, and sensory indices of the fresh-cut Hami melons were also evaluated. Compared to the contr...
Source: Molecules - Category: Chemistry Authors: Tags: Article Source Type: research
Publication date: Available online 25 June 2019Source: Food ControlAuthor(s): Zijin Zhou, Sophie Zuber, Matteo Campagnoli, Thierry Putallaz, Frank Devlieghere, Mieke UyttendaeleAbstractThe microbial safety of black peppercorns (Piper nigrum L.) has raised concerns due to increasing numbers of reported foodborne outbreaks and food safety alerts. To avoid quality degradation caused by excessive thermal processing, mild steaming treatments (
Source: Food Control - Category: Food Science Source Type: research
Abstract Fresh vegetables are important components of an everyday balanced diet making ready to-eat-salads (RTE) a commodity widely consumed. However, in the past few years these products have been linked with outbreaks of salmonellosis and listeriosis; thus the continuous investigation of their safety is an essential requirement. A total of 216 samples of ready-to-eat salads from the Cypriot market were analysed to determine the microbiological quality and safety, along with physicochemical attributes of the salads and identify possible correlations between them. The samples were randomly collected from four reta...
Source: Food Microbiology - Category: Food Science Authors: Tags: Food Microbiol Source Type: research
CONCLUSION: The occurrence of genetically similar diarrheagenic E. coli in both groups of children, likewise resistant to these agents, underscores the importance of establishing strategies for the prevention of outbreaks, especially among low-income households. PMID: 31199225 [PubMed - as supplied by publisher]
Source: Journal of Medical Microbiology - Category: Microbiology Authors: Tags: J Med Microbiol Source Type: research
Lixing Huang1, Lingmin Zhao1, Wenjia Liu1, Xiaojin Xu1, Yongquan Su2, Yingxue Qin1 and Qingpi Yan1,2* 1Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Jimei University, Ministry of Agriculture, Xiamen, China 2State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China Pseudomonas plecoglossicida is a temperature-dependent opportunistic pathogen which is associated with a variety of diseases in fish. During the development of “white nodules” disease, the expression of htpG in P. plecoglossicida was found to be significantly up-regulated at its virulent tempera...
Source: Frontiers in Immunology - Category: Allergy & Immunology Source Type: research
In this study, a transposon mutagenesis approach was applied to reveal the factors involved in resistance to oxidative stress, and the biofilm formation among mutants and WT strains were further detected using crystal violet staining (CVS), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM) to reveal potential relationship between oxidative stress and biofilm formation. Materials and Methods The Development of Mutants Library The procedure of transposon mutagenesis approach was performed as described by Zhang et al. (2018). Screening of Mutants Tolerance to Oxidative Stress For screening...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
We describe a ceftriaxone-resistant Salmonella Typhi bacteraemia in a pregnant woman returning from a family visit in Pakistan. Whole genome sequencing confirmed similarity to a Pakistani outbreak clone. Pregnancy and unawareness of this outbreak delayed appropriate antibiotic therapy. Concurrently, we detected faecal carriage of a carbapenemase-producing Escherichia coli. Awareness of the ongoing outbreak should affect empiric treatment of typhoid fever and hygiene precautions in travellers returning from Pakistan. Meropenem may be warranted in severe cases. PMID: 31138366 [PubMed - in process]
Source: Euro Surveill - Category: Infectious Diseases Authors: Tags: Euro Surveill Source Type: research
In conclusion, the results improve our understanding on the characteristics of lncRNAs and mRNAs on regulating host immune response against C. perfringens type C infection, which will provide a reference for future research into exploring C. perfringens-related diseases in human. Introduction Clostridium perfringens (C. perfringens) is a Gram-positive anaerobic rod and ranks as the second most common bacteria that causes fulminant, fatal infectious and immune diseases (Scharff, 2012; Grass et al., 2013). These diseases are characterized by fever, pain, gas production, local edema, and severe tissue destruction, the...
Source: Frontiers in cellular and infection microbiology - Category: Microbiology Source Type: research
Conclusion Since B. cereus group are highly similar in biochemical as well as genetic profiles, a new biomarker was developed for identifying and distinguishing B. thuringiensis from the closely related group. The performance of XRE was compared with cry2 gene and artificially contaminated samples were also tested. Compared with cry2, XRE gene was observed to be efficiently accurate in the identification of B. thuringiensis. Further, the developed real-time PCR using XRE successfully identified B. thuringiensis and it could be used to quantify cell numbers with the generated standard curve. Author Contributions The expe...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
Blessing O. Anonye1, Jack Hassall2, Jamie Patient3, Usanee Detamornrat3, Afnan M. Aladdad3, Stephanie Schüller4,5, Felicity R. A. J. Rose3 and Meera Unnikrishnan1* 1Microbiology and Infection Unit, Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom 2Warwick Integrative Synthetic Biology Centre, School of Life Sciences, University of Warwick, Coventry, United Kingdom 3Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom 4Norwich Medical School, F...
Source: Frontiers in Microbiology - Category: Microbiology Source Type: research
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