FIG. 5.

Comparison of V. cholerae O1 El Tor strains A1552 and N16961 for biofilm phenotype and vps gene expression. (A) Biofilm-forming phenotypes of the smooth strains A1552 and N16961. Biofilm formation was analyzed by growing the strains in LB broth at 30°C for 24 h in polyvinyl chloride microtiter plates, and then the biofilms were quantified by crystal violet staining. The biofilm-forming capacity of the N16961 strain after 24 h of growth in polyvinyl chloride microtiter plates is twofold higher than that of the A1552 strain. (B) Expression analysis of vps genes in the strains A1552 and N16961. The abundance of vpsR, vpsA, and vpsL messages was quantified by copy number determination using real-time PCR. All three genes were expressed at a higher level in N16961 than in A1552.