STUDIES ON THE SPORES OF AEROBIC BACTERIA I

Abstract

Free spores of aerobic spore-forming bacilli contain a highly active enzyme which catalyzes the conversion of L-alanine to D-alanine. The properties of this enzyme are similar to the alanine racemase found in Streptococcus faecalis by Wood and Gunsalus (Jour. Biol. Chem. 190: 403). The content of alanine racemase in spores of Bacillus terminalis is 16 times greater than in vegetative cells of the same strain. The increase in enzyme follows closely the degree of sporulation. The pH optimum of alanine racemase in spores is about 8.6. The enzyme is specific for alanine, of the substances tried, and has a low affinity for substrate. The racemization of alanine by spores does not require pyridoxal phosphate, and is remarkably heat-stable, losing less than 5% of its activity after being heated at 80[degree]C for 2 hours. In contrast, vegetative cell racemase is almost completely inactivated after 15 min. at 80[degree]C.