Isolation and mapping of a new suppressor mutation of an early sporulation gene spoOF mutation in Bacillus subtilis.

We constructed an spoOF deletion (spoOF delta S) mutant of Bacillus subtilis by inserting a chromosomal segment carried by plasmid pUBSF delta S. This plasmid carries a 0.7-kilobase pair deletion that removes the spoOF promoter and a part of the structural gene. We used the spoOF deletion mutant to isolate a new intergenic suppressor of the spoOF phenotype, designated sof1. The sof1 suppressor completely restores the sporulation ability of all spoOF defective mutants tested, including spoOF77, spoOF221 and spoOF delta S. The sof1 suppressor maps to the left of lys1 on the B. subtilis chromosome, in a region rich in sporulation markers and distant from the spoOF locus.