Quantitative PCR. Gene expression was determined for selected genes. Total RNA was isolated from wild-type 8081c cells and their isogenic flhD and fliA mutants. mRNA was reverse transcribed to cDNA and qPCR was performed. Data were normalized with dnaE, polA, and gapA (housekeeping genes). Expression ratios compare the expression levels between wild-type cells and flhD (darker bars) and fliA (lighter bars) mutants. Genes that are expressed higher in wild-type cells are printed in green, genes that are expressed higher in the mutants are printed in red, peptide transport genes are printed in blue. The fleC gene constitutes our internal control and is printed in black. The experiment was performed three times with each of three independently grown bacterial cultures and the mean of the population is presented. Error bars indicate 1 s.