Influence of pH on bile sensitivity among various strains of Listeria monocytogenes under aerobic and anaerobic· conditions
White, Sally J.
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Listeria monocytogenes is a bacterium that causes the food-borne disease listeriosis and survives the body's natural defenses within the digestive tract, including the acidic conditions and bile. Limited information is available concerning the ability of L. monocytogenes to resist bile under anaerobic conditions, especially at acidic pH. In this study, the survival strains was analyzed under aerobic and anaerobic conditions following exposure to bile. Exposure to bile at acidic pH increased toxicity of bile, resulting in an initial significant reduction in strain survival. Anaerobic cultivation increased bile resistance, but a significant increase was only observed in virulent strains when exposed to bile at acidic pH. Together, these data suggest that the ability to sense and respond to oxygen availability may influence the expression of stress response mechanisms. Further research is needed to determine how L. monocytogenes senses and responds to oxygen and how this varies between invasive and non-invasive strains.