Autolysis of Listeria monocytogenes

Physiological conditions that could provide maximal rates of autolysis of Listeria monocytogenes were examined. L. monocytogenes was found to be refractory to most treatments that promote rapid autolysis in other bacteria. Best rates of autolysis were obtained after resuspending the cells in Tris-hydrochloride buffer at 37 degrees C with the pH optimum at 8.0. Autolysis was also efficiently promoted by the surfactant Triton X-100. Antibiotics that interfere with the biosynthesis of the cell wall murein (peptidoglycan) caused death of the cells without autolysis after prolonged incubation in the presence of the drug. Only nisin, which has been shown to bind in vitro to the murein precursors lipid I and lipid II brings about autolysis of L. monocytogenes cells, although with slower kinetics than in the case of Tris-HCl and Triton.