FIG 3.

Multiple transcriptional regulators affect biofilm formation in C. perfringens. (A) Pellicle biofilm formation at 25°C by ctrAB, spo0A, or abrB mutant strains. The cells were incubated at 25°C for 2 days. The edges of pellicle biofilms formed at the bottom of wells were picked and flipped through gentle pipette aspiration. (B) Adhered-biofilm formation of the mutant strains. The cells were cultured at 25 or 37°C for 2 days and stained with crystal violet. (C) Quantification of the adhered-biofilm biomass. The means and standard deviations of the OD₅₇₀ values of three independent experiments are shown. (D) Confocal microscopy images of the mutant strain biofilms formed at 25°C. The arrows indicate the substrate surface. (E) Scanning electron microscopy of the mutant cells in the biofilms formed at 25°C. The bars indicate 30 μm (D) or 2 μm (E).