Construction of the sll0528 mutant. (a) The coding region of the sll0528 gene was replaced with a chloramphenicol resistance gene cassette (Cmr) obtained from pACYC184. The arrows P1 to P8 indicated the primers used in PCR verification; (b) PCR verification of the sll0528 mutant. Template was genomic DNA from wild type (lanes 1, 3, 5, 7, 9) or sll0528 mutant (lanes 2, 4, 6, 8, 10). Primers used as indicated (a) were P5 + P6 (lanes 1, 2), P7 + P8 (lanes 3, 4), P1 + P6 (lanes 5, 6), P4 + P5 (lanes 7, 8) and P1 + P4 (lanes 9, 10). PCR products were sequenced to confirm their authenticity.