Restriction fragments that exert promoter activity during postexponential growth of Bacillus subtilis

Two restriction fragments of Bacillus subtilis DNA were identified which caused the cat-86 gene present on the promoter cloning plasmid pPL703 to be activated predominantly during postexponential growth of host cells. The postexponential increase was observed in both sporulation-positive strains and in a spoOA mutant of B. subtilis. However, the postexponential increase in the cat-86 gene product, chloramphenicol acetyltransferase, was diminished or not observed when the plasmid-containing cells were grown in the presence of excess glucose. The promoter-containing fragment, designated as 33, was mapped to a site on the B. subtilis chromosome adjacent to hisA. The other fragment, 14, mapped to a site adjacent to ctrA. When present on a high-copy vector, both fragments caused a reduction in the sporulation frequency of host cells. Fragment 33 in high copy number conferred on B. subtilis cells three additional phenotypic changes: brown colony color, intracellular inclusions, and, in a protease-deficient mutant, the production of extracellular protease activity. These activities were observed only in postexponential-phase cultures.