FIG 8.

Expression of protease genes in wild-type Serratia sp. SCBI and mutants. qRT-PCR was performed on RNA extracted from wild-type Serratia sp. SCBI and mutant cultures grown in LB medium for 18 h at 22°C or 28°C. mRNA levels were normalized to the rplU housekeeping gene and compared to the calibrator (wild-type [WT] SCBI). Data are presented as the relative changes in gene expression between the values obtained from the protease mutants and the calibrator. (A to D) Expression levels of prtA1 and prtA2 at 28°C (A), prtA3 and prtA4 at 28°C (B), serine protease 1 and serine protease 2 at 22°C (C), and the secreted metalloprotease (exponential-phase cells) and yfgC at 22°C (D). Values are means ± standard deviations (error bars) from at least two independent experiments. Relative gene expression values that are significantly different (P < 0.05) from the value for the calibrator (WT SCBI) are indicated by an asterisk.