Construction of bb0219 disruption mutants and complemented strains. (A) Schematic representation of bb0217–bb0220 genes in the Bb chromosome, insertion of the PflgB-kan gene cassette by homologous recombination, and the relevant complementation plasmid. Arrows indicate the approximate positions of the oligonucleotide primers used for subsequent PCR analyses. (B) PCR analysis of WT 297, bb0219 mutants, and the complemented strains. The bb0219-specific primer pairs used in PCR are indicated on the right. Lane 1, WT 297; lane 2, bb0219 mutant OY04/D4; lane 3, mutant OY04/F42; lane 4, complemented strain OY06/D11; lane 5, complemented strain OY06/F6; lane 6, mock-complemented strain OY07/F1; and lane 7, mock-complemented OY07/F62. (C) RT-PCR was used to determine the presence or absence of bb0219 transcripts. Lanes and primer pair designations are as in B.