Listeria monocytogenes growth limits and stress resistance mechanisms

The food-borne pathogen Listeria monocytogenes is a Gram-positive facultative anaerobic rod, which is the causative agent of listeriosis. Due to the severity of the disease and the fact that its incidence is increasing in numerous European countries, L. monocytogenes is of great public health concern. This bacterium shows relatively high resistance to environmental insults compared with many other non-spore-forming food-borne pathogens. It is able to grow at low pH, at high salt concentrations, and low temperatures. The possibility that this pathogen (cross-) contaminates food products is a major concern for the food industry. Therefore, it is important to investigate the diversity in growth potential and stress resistance (mechanisms) of L. monocytogenes strains during exposure to commonly used preservation conditions. Several approaches are described in this thesis, including comparison of stress resistance and growth limits of a large collection of natural isolates, screening a mutant library for stress sensitive mutants, and transcription profiling of stress responses. The function of various stress response genes and mechanisms including the so-called SOS response are furthermore investigated in detail.

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Bibliographic Details
Main Author: van der Veen, S.
Other Authors: Abee, Tjakko
Format: Doctoral thesis biblioteca
Language:English
Subjects:growth, listeria monocytogenes, stress response, stress tolerance, groei, stressreactie, stresstolerantie,
Online Access:https://research.wur.nl/en/publications/listeria-monocytogenes-growth-limits-and-stress-resistance-mechan
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Summary:The food-borne pathogen Listeria monocytogenes is a Gram-positive facultative anaerobic rod, which is the causative agent of listeriosis. Due to the severity of the disease and the fact that its incidence is increasing in numerous European countries, L. monocytogenes is of great public health concern. This bacterium shows relatively high resistance to environmental insults compared with many other non-spore-forming food-borne pathogens. It is able to grow at low pH, at high salt concentrations, and low temperatures. The possibility that this pathogen (cross-) contaminates food products is a major concern for the food industry. Therefore, it is important to investigate the diversity in growth potential and stress resistance (mechanisms) of L. monocytogenes strains during exposure to commonly used preservation conditions. Several approaches are described in this thesis, including comparison of stress resistance and growth limits of a large collection of natural isolates, screening a mutant library for stress sensitive mutants, and transcription profiling of stress responses. The function of various stress response genes and mechanisms including the so-called SOS response are furthermore investigated in detail.