
Full text loading...
A Bacillus subtilis gerC spore germination mutant demonstrating a temperature-sensitive response to l-alanine as germinant has been characterized in detail. The gerC58 mutation is 50% cotransformed with aroB in the gene order gerC-aroB-trpC. The mutation is responsible for a severe growth defect which is manifest at all growth temperatures and is most extreme on rich media. A second, unlinked, mutation in the original strain suppressed this growth defect, but spores of the suppressed strain failed to germinate in alanine at 42 °C. As this germination defect is dependent on the presence of the gerC58 allele, it is likely to be the direct result of a mutant gerC protein. The gerC gene therefore appears to have a role in both spore germination and vegetative cell growth. A gene library of BclI-digested B. subtilis chromosomal DNA was constructed in phage vector 𝜙105J27. A derivative containing the gerC region was obtained by complementation of the growth defect of an unsuppressed gerC58 strain. This phage contained a 6·3 kb insert of bacterial DNA, which is above the reported packaging limit of the phage. It failed to form visible plaques, although it could be handled as a prophage and sufficient phage particles be isolated to allow characterization of the insert. A deletion derivative generated in vitro and carrying only 2·9 kb of insert DNA also complemented the gerC defect. This gerC locus is the second locus to be implicated in alanine-stimulated germination. The first, gerA, is a developmentaly controlled operon whose gene products are present only in the spore. This study of gerC, in contrast, reveals a role in spore germination for a normally essential vegetative protein.