Germination of unactivated spores of Bacillus cereus T. Effect of preincubation with L-alanine or inosine on the subsequent germination.

Heat-activated spores of Bacillus cereus T germinate rapidly in the presence of L-alanine alone or inosine alone. In contrast, unactivated spores can not germinate in the presence of either germinant alone but rapidly in the presence of both germinants. The highest level of cooperative action of L-alanine and inosine on the germination was observed when they were present in a ratio 1:1. Preincubations of unactivated spores with L-alanine or inosine had opposite effects on the subsequent germination in the presence of both germinants: preincubation with L-alanine stimulated the initiation of subsequent germination, while preincubation with inosine inhibited it. These results suggest that germination of unactivated spores initiated by L-alanine and inosine includes two steps, the first initiated by L-alanine and the second prompted by inosine. The effect of preincubation of unactivated spores with L-alanine was not diminished by washings. The pH dependence of the preincubation of unactivated spores was not so marked as that of the subsequent germination in the presence of inosine.