CHARACTERIZATION OF THE ACTION OF LYSOZYME ON STAPHYLOCOCCUS AUREUS AND ON MICROCOCCUS LYSODEIKTICUS
Journal of Bacteriology
A recent report from this laboratory (Kingkade, Huff, and Behrens, 1948) (Iescribes experiments in which lysozyme was used to prepare bacterial cell lysates from Staphylococcus aureus K1 for use as a possible medium for bacteriophage multiplication. It was hoped that the cell wall would be ruptured allowing dispersal of the intracellular constituents into the medium without appreciable denaturation or destruction. Since in many of the experiments filtration had been used to remove any intact
... ls from the cell lysates, experiments were undertaken to determine whether the intracellular constituents had dispersed sufficiently to be filterable.' For this purpose electron micrographs were made of cells treated for various times with lysozyme. At the same time turbidimetric readings and determinations of cell count, both direct and viable, were made to be correlated with the results of electron micrography. Observations w^ere also made on the filtrates from the staphylococcal lysates. The action of lysozyme on Staphylococcus aureus K1 is accompanied by a gradual decrease in density at the periphery of the cell. No evidence was found of rupture of a cell membrane with a spilling of the cellular contents. The cellular masses remaining in the lysates did not pass through bacterial filters. In contrast, lysozyme causes rupture of the cell wall of Micrococcus lysodcikliclus and a dispersal of the cell contents. EXPERIMENTAL METHODS The Staphylococcus aureus strain K1 and Mficrococcus lysodeikticus MB79 (7R-2150)2 were grown at 37 C on nutrient agar (1 per cent Difco nutrient broth, 0.85 per cent NaCl, 2.5 per cent agar) in toxin bottles. After incubating for 24 hours, the cells were washed from the agar with saline. They were sedimented by centrifugation, washed once with saline, and suspended in sufficient saline to give a concentration of 1 to 3 X 109 cells per ml. Duplicate tubes containing 7.2 ml of cell suspension and 0.8 ml of lysozyme3 in saline were incubated at 35 to 37 C with aeration. Control tubes containing 1 Dr. S. E. Luria had suggested that lysis might be incomplete.