Chemotaxis in Listeria monocytogenes

Listeria monocytogenes is a flagellated bacterium with a characteristic tumbling motion. It is intriguing to speculate that directional motility might facilitate penetration of the intestinal epithelium or selective colonization of the central nervous system or gravid uterus. There are conflicting reports on the extent of flagellation and degree of motility at temperatures corresponding to the internal environment of the mammalian host. No studies of chemotaxis in Listeria have been reported. We examined Listeria for flagella, motility, and chemotaxis after growth at 10 degrees, 24 degrees, 30 degrees, 37 degrees and 40 degrees C. Listeria grown at all temperatures possessed flagella and were motile to at least some degree. Those grown at 24 degrees or 30 degrees C were the most abundantly flagellated and the most vigorously motile. The bacteria were able to swim towards tryptose at all temperatures and toward glucose at all temperatures except 40 degrees C.