FIG 2.

Fluorescence-based method to quantify C. perfringens biofilms. Strain CN3685 was inoculated in 96-well plates containing THY and incubated at 37°C for the indicated time. Biofilms were washed with PBS and then stained with crystal violet, after which the absorbance (A₆₃₀) was obtained (A), or fluorescently stained with SYTO9, and fluorescence arbitrary units were obtained with a fluorometer (B). The biofilm biomass (%) was calculated in panels A and B by setting 100% biomass units obtained for the 8-h time point to calculate the biomass (%) of the other two. *, Statistical significance (P < 0.05), as evaluated by the Mann-Whitney U test. Error bars represent the standard errors of the mean calculated using data from three independent experiments. (C) Biofilms stained in panel B were photographed using an inverted microscope and either the EVOS light-cube green fluorescent protein 470/510 (SYTO9) or phase contrast. The scale bar at the bottom right applies to all six panels.