Screening of glutamate decarboxylase activity and bile salt resistance of human asymptomic carriage, clinical, food, and environmental isolates of Listeria monocytogenes

Following consumption, stomach acidity is the first major barrier encountered by thefood-borne pathogen Listeria monocytogenes. Analysis of low pH sensitivity and glutamatedecarboxylase (GAD) acid resistance system of 14 isolates of L. monocytogenes carriedasymptomatically by humans showed that leve...

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Bibliographic Details
Published in:International journal of food microbiology 2004, Vol.93 (1), p.87-99
Main Authors: Olier, Maïwenn, Rousseaux, Sandrine, Piveteau, P., Lemaître, J.P., Rousset, André, Guzzo, G.
Format: Article
Language:English
Subjects:
Life Sciences
Microbiology and Parasitology
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Summary:Following consumption, stomach acidity is the first major barrier encountered by thefood-borne pathogen Listeria monocytogenes. Analysis of low pH sensitivity and glutamatedecarboxylase (GAD) acid resistance system of 14 isolates of L. monocytogenes carriedasymptomatically by humans showed that levels of GAD activity was subjected to strainvariation. Similar variations were observed for strains responsible of 18 listeriosis, whereas incomparison, 13 strains isolated from food and from food-processing plant environmentshowed lower GAD activity. Following survival of the stomach barrier, L. monocytogenesalso has to resist to bile salts encountered in the small intestine. Analysis revealed that allstrains tested were able to grow in presence of bile salts with concentrations as high as thoseencountered in the small intestine and had the previously identified Bile Salt Hydrolase(BSH) activity. Strain variation was observed but there was no relationship between the originof the strains and the ability to degrade bile salts.
ISSN:0168-1605