CATABOLITE REPRESSION OF HISTIDASE BIOSYNTHESIS IN BACILLUS-SPHAERICUS BY ACETATE

Bacillus sphaericus grew with increasing doubling times on acetate, gluconate, histidine, arginine and succinate as carbon and energy sources. When grown with both acetate and histidine, B. sphaericus used the former preferentially and diauxic growth was observed, although there was no detectable lag between the two growth phases. Histidase, the first enzyme of the histidine utilization pathway, was induced by histidine but not in the presence of acetate. In the absence of an alternative nitrogen source, B. sphaericus was unable to grow with acetate as carbon source and histidine as nitrogen source (presumably because of repression of histidase biosynthesis), although it could grow on histidine alone. Acetate also inhibited sporulation in R sphaericus.