LISTERIA-MONOCYTOGENES INFECTION OF CACO-2 CELLS - ROLE OF GROWTH TEMPERATURE

The aim of the present study was to evaluate the role of temperature i n the virulence of Listeria monocytogenes, a Gram-positive facultative intracellular food-borne pathogen. The capacity of bacteria grown at 37, 25 and 4 degrees C to develop haemolytic activity, to enter the Ca co-2 enterocyte-like cell line and to multiply intracellularly was inv estigated. We demonstrated that L. monocytogenes penetration was not s ignificantly influenced by the growth temperature of cultures and that bacteria grown at low temperature were capable of synthesizing intern alin and, during the infection process, of restoring the haemolytic ph enotype which is normally lacking in the extracellular environment at 4 and 25 degrees C. It can be concluded that L. monocytogenes, frequen tly present in numerous environmental sources and also in refrigerated food products, produces at low temperature, the virulence factors nec essary to invade intestinal cells.