Inactivation and complementation of sgcR3. A, The plasmid pOJR3KO, constructed for sgcR3 inactivation as described in Methods, was used for gene disruption. Predicted restriction enzyme polymorphism caused by gene replacement is shown. B, Bam HI; Bc, Bcl I; E, Eco RV. B, Southern blot hybridization of Bam HI-digested chromosomal DNA of wild type strain (lane 1) and R3KO mutant (lane 2). Left arm for crossover is used as hybridization probe. C, Southern blot hybridization of Eco RV and Bcl I-digested chromosomal DNA of wild type strain (lane 1 and 2) and R3KO mutant (lane 3 and 4). Deleted part of sgcR3 gene is used as hybridization probe. D, Determination of C-1027 production in complementation strains of sgcR3. The antibacterial activities against B. subtilis of wild type strain (a), R3KO mutant (b), R3KO mutant with pKCR3 (c), R3KO mutant with pSETR3 (d) and R3KO mutant with pLR3 (e) are shown.