Use of temperature-sensitive mutants to study gene expression of two closely linked sporulation loci in Bacillus subtilis.

The spoOB and spoIVF loci are contiguous on the chromosome of Bacillus subtilis, so that genes in these loci may be parts of a single polycistronic operon. Temperature-sensitive strains having mutations in these loci were isolated, and temperature-shift experiments were carried out to investigate expression of the genes. The temperature-sensitive periods of spoOB mutants extended from the beginning of sporulation until the end of the stage II. The temperature-sensitive periods of spoIVF strains were during stage IV of sporulation. Therefore, although the spoOB and spoIVF loci are contiguous on the chromosome it is unlikely that genes in them are parts of a single polycistronic operon.