Inhibition of cell division in Micrococcus lysodeikticus dis-II.

Abstract

A strain of Micrococcus lysodeikticus (designated dis-II) has been isolated by nutritional selection using aspartic acid as the major source of carbon, nitrogen, and energy. This organism is inhibited from dividing when grown in a defined medium in the presence of D-serine, penicillin, mitomycin c or under conditions of suboptimal magnesium concentration. All of the division-inhibiting compounds decrease growth yields and induce varying amounts of lysis. L-Lysine, when added to D-serine-containing media, allows some increase in growth yields, but division inhibition appears more pronounced. Pantoyl lactone, D- and L-alanine, and to a lesser extent Carbowax 400 (hypertonic conditions) and glycine, but not spermine, will significantly prevent but not reverse division inhibition in D-serine-lysine-containing media. Thin-slicing and electron microscopic observation of non-dividing cells shows that a relatively thick layer of porous-appearing cell wall mucopeptide is synthesized when cells are grown in the presence of D-serine. These cells as well as those grown in the presence of penicillin or mitomycin c are not lysed in distilled water. Amount of cell wall mucopeptide is greatly decreased in cells grown under conditions of suboptimal magnesium concentration; these cells undergo extensive lysis in distilled water.