Characterization and mapping of Bacillus subtilis gerD mutants.

Abstract

A mutant of Bacillus subtilis 168 unable to germinate in DL-alanine+fructose+glucose was isolated and proved to be deficient in response to fructose. Spores of this mutant responded to L-alanine fairly well although the germination rate was slower than the wild type. Analysis of the effect of fructose on the D-alanine inhibition of L-alanine-triggered germination showed that in wild type spores, fructose reversed the inhibition by lowering the spore''s affinity with D-alanine whereas the mutant spores lacked this response. Since the mutation was mapped in the gerD locus, a standard gerD strain, 4738 (gerD48), was studied for comparison. Strain 4738 showed similar germination properties except that germination of this strain in L-alanine was much slower. These findings revealed a germinant-specific character of gerD mutants whose defect had been regarded as non-specific with respect to germinants. PBS1 transduction crosses suggested the gene order cysA-attSPO2-gerD-ada.