Germination of Bacillus cereus endospores: a proposed role for heat shock and nucleosides.

Spores of Bacillus cereus T prepared in a glucose - yeast extract - salts broth germinated in L-alanine or more rapidly in L-alanine plus inosine or adenosine. The nucleosides alone were not germinative. Inosine was shown to produce no pregerminative changes in spores that prepared them for more rapid germination later in L-alanine. Experiments which measured the interaction of nucleosides, heat shock, and D-alanine on germination rates suggested that nucleosides may potentiate L-alanine-induced germination by causing discrimination against D-alanine at the L-alanine binding site(s) in the spore. D-Alanine is germinative when used with inosine probably because of L-alanine formation by alanine racemase. Heat shock, a prerequisite to D-alanine plus inosine-induced germination, may facilitate entry of inosine into the spore in amounts needed to discriminate against D-alanine.