FIG 8 .

Regulation of chitinase genes by RpoQ. (A) Exochitinase activity of wild-type V. fischeri cells harboring either pTM214 (WT vector) or pXDC10 (WT P_trc-rpoQ), strain CA1 harboring either pTM214 (ΔrpoQ vector) or pXDC10 (ΔrpoQ P_trc-rpoQ), and TIM358 harboring pTM214 (ΔlitR vector). Secreted chitinase activity was determined in the cell-free supernatant. Graphical and error bars indicate, respectively, the averages and standard deviations of data from three independent experiments. Shared letters above the bars indicate no statistically significant difference (P > 0.05), whereas different letters indicate a significant difference (P < 0.05) in exochitinase activity between those strains (ANOVA and Tukey’s HSD test). (B) Wild-type cells carrying the empty vector plasmid (pTM214; white bars) or the inducible rpoQ allele (pXDC10; black bars) were grown in LBS medium supplemented with 1 mM IPTG and harvested at an OD₆₀₀ of 1.4 to 1.5. VF_0986, chitodextrinase; VF_0655, endochitinase; VF_1598, exochitinase; VF_A0715, chitodextrinase precursor; VF_1146, chitodextrinase precursor; VF_1390, chitinase; VF_1059, chitinase. Graphical and error bars indicate, respectively, the averages and standard deviations of data from four independent experiments. The asterisks indicate a significant difference in transcription levels between each set of paired strains.