Adenosine deaminase and ribosidase in spores of Bacillus cereus

Inosine is a more effective germination stimulant than adenosine for spores of Bacillus cereus and B. anthracis (Powell & Hunter, 1955). A crude method of assessment, based on the paper-ionophoresis technique of Wade & Morgan (1954), indicated that extracts from disintegrated resting spores of B. cereus converted adenosine into inosine. This suggested the possibility that inosine might be, in fact, the germination stimulant, and that germination of a given spore suspension in adenosine might depend, to some extent, on its adenosine-deaminase activity. We have now studied quantitatively the deamination of adeno- sine by resting and germinated spores of B. cereus, and also its further breakdown to the purine and free ribose. The possible relationships between these reactions and spore germination in B. cereus are discussed. Part of this work has already been briefly reported (Powell, 1955).