Figure 3. Effects of small RNA overexpression on biofilm formation in E. coli.

(a) To characterize the biofilm forming ability of E. coli overexpressing sRNAs, a collection of strains containing each sRNA-expressing plasmid were grown in LB containing 1 mM IPTG and 100 μg/mL ampicillin at 30 °C for 12 h, and the amount of biofilm attached to 96-well round bottom polystyrene microtiter plates was measured via crystal violet staining. (b) The level of biofilm formation (OD₅₅₀) was expressed relative to cell growth (OD₅₉₅), and termed ‘biofilm index’. The biofilm index value was normalized to control cells containing plasmid vector (pHMB1) and designated ‘relative biofilm index’. (c) Effects of ArcZ, DsrA, and SdsR sRNAs on biofilm formation in the MG1655Δhfq background. (d) Comparison of relative biofilm formation by MG1655 and MG1655Δhfq strains. Relative biofilm indexes are shown on a bar graph (axis on the left) and the growth of each strain as a line graph (axis on the right).