FIG. 4.

Identification of B. bacteriovorus HD100 knockout mutants. By using primers Bd29 and Bd30, PCR amplification of genomic DNA of wild-type stains yields a PCR product of 696 bp, while using genomic DNA of the saprophytic mutant isolated through transposon mutagenesis yields a PCR product of 1695 bp. Lane 1 shows the hit-containing PCR fragment of the wild type; in lane 2, the merodiploid state is visible, and lane 3 shows the PCR product from the saprophytic knockout mutant after allelic exchange.