Spores of
Bacillus cereus T can germinate by the cooperative action of L-alanine and inosine. Addition of both compounds in the following order, however, weakend the action; inosine first and L-alanine second. To find the cause of the decrease in the extent of germination, we studied the inosine-cleaving activity of the spores and obtained the following results.
1) Incubation of the spores with 0.05mM inosine resulted in a progressive production of hypoxanthine. Hypoxanthine, D-ribose and other inosine analogs showed little effect on germination of the spores induced by 0.05mM L-alanine and 0.05mM inosine.
2) Formycin B, the closest analog of inosine, was not cleaved by the spores. Germination of the spores was induced by formycin B in the presence of L-alanine. No influence on germination was observed when the spores were incubated with formycin B (0.025-1.0mM) for 1hr and then 0.05mM L-alanine was added.
These results clearly show that the decrease in the extent of germination of the spores preincubated with inosine is due to the cleavage of inosine by the spores during the preincubation.
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