Fig. 3. LeuO enhances vibrio exopolysaccharide gene expression and inhibits motility.
A. Strain O395ΔlacZ (Wt) and its ΔvieA isogenic mutant containing a vpsL-lacZ promoter fusion (Wang et al., 2012b) were transformed with pBAD33 (□, open bar) or pBAD-LeuO (■, filled bar) and grown to stationary phase in the presence of L-arabinose (0.2 %). β-galactosidase activity (Miller units) was measured as an indicator of promoter activity. The error bars denote the standard deviation of five independent transformants. Symbols: * p < 0.05 (ΔvieA versus Wt comparison, unpaired T- test). B. Overnight cultures of the above strains (six independent transformants per strain) were stabbed into 3 mL of swarm agar in 6-well microtiter plates. Plates were incubated 24 h at 30°C and photographed. The swarm halo (mm) ± STDEV (n = 6) are indicated within each representative picture.