Fig. (3) lac promoter-driven biofilm formation by WT and lacI expressing strains. Cultures of wild-type (ES114) and lacI^q (KV6576) strains containing either the empty vector pVSV105 or RscS expression plasmid pCLD46 were grown in LBS containing Cm. Aliquots were diluted to an OD₆₀₀ of 0.2, spotted onto LBS-Cm medium containing or lacking 1.75 mM IPTG, and incubated at room temperature. Wrinkled colony formation was assessed at 20 and 50 h post inoculation.