Mutation of rpoS delays the up regulation of chbC expression during GlcNAc starvation. Growth of B. burgdorferi strains B31-A (WT), A74 (rpoS mutant), and WC12 (rpoS complemented mutant) in BSK-II without GlcNAc (closed circle, B31-A; closed triangle, A74; closed square, WC12) and expression of chbC transcript in each strain (open circle, B31-A; open triangle, A74; open square, WC12). Late-log phase cells from each strain were diluted to 1.0 × 105 cells ml-1in BSK-II lacking GlcNAc, and RNA was extracted from each strain at various times during growth. Expression of chbC was determined by qRT-PCR and the fold change from the initial time point (44 h) was calculated. For expression analyses, duplicate measurements were performed for two biological replicates. Error bars represent the standard error of the mean.