Initiation of Spore Germination in Bacillus subtilis : Relationship to Inhibition of l -Alanine Metabolism

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Abstract
The inhibitory effects of anthranilic acid esters (methyl anthranilate and N -methyl anthranilate) on the l -alanine-induced initiation of spore germination was examined in Bacillus subtilis 168. Methyl anthranilate irreversibly inhibited alanine initiation by a competitive mechanism. In its presence, the inhibition could be reversed only by the combined addition of d -glucose, d -fructose, and K + . Both l -alanine dehydrogenase and l -glutamate-pyruvate transaminase, enzymes which catalyze the first reaction in l -alanine metabolism, were competitively inhibited by methyl anthranilate. The K i values for germination initiation (0.053 mM) and of l -glutamate-pyruvate transaminase (0.068 mM) were similar, whereas that for l -alanine dehydrogenase (0.4 mM) was six to seven times higher. Since a mutant lacking l -alanine dehydrogenase activity germinated normally in l -alanine alone, it is speculated that the major pathway of l -alanine metabolism during initiation may be via transmination reaction.