Fig 4.
OmpA regulates bacterial biofilm formation in vitro. (A) Sodalis PT and Sodalis ΔOmpA cells were shaken vigorously at an angle for 7 days in 15-ml Falcon tubes. The bacterial splash zone was subsequently stained with crystal violet to visualize the presence or absence of a biofilm. These structures were present in the tubes containing Sodalis PT cells (shown enlarged in the corresponding box). Sodalis ΔOmpA cells failed to form a biofilm. This experiment was performed in triplicate with 3 distinct clonal populations of each bacterial strain. (B) Spectrophotometric quantification of relative biofilm formation exhibited by Sodalis PT and Sodalis ΔOmpA cells. (C) E. coli ΔOmpA cells exhibit a biofilm formation defect that is restored in their counterparts that were genetically modified to express Sodalis ompA (E. coli ΔOmpA pIOSodalis cells). In panels B, C and D, statistical significance was determined by the Mann-Whitney test.