ERRATUM
Volume 7, no. 4, e01237-16, 2016, https://doi.org/10.1128/mBio.01237-16. In Fig. 4, panel A was a duplicate of panel F. The figure has been revised. The correct image for panel A is shown below.
FIG 4 .
Culture supernatant fluids collected from the agrB1D1 mutants are not cytotoxic to human foreskin fibroblast cells. Strain 630 and R20291 agrB1D1 and agrB2D2 mutants were cultured for 48 h in BHI medium anaerobically at 37°C. The culture supernatant fluids were collected, filter sterilized with a 0.45-µm filter, and examined for cytotoxicity with the Bartels Clostridium difficile cytotoxicity assay kit (Trinity Biotech, Jamestown, NY). The culture fluids were incubated with the fibroblast cells for 24 h and observed under a microscope for cytotoxic effects. Images were taken with an EVOS XL microscope (Advanced Microscopy Group) at ×20 magnification. Panels: A, a representative image of fibroblast cells cultured in growth medium only; B, wild-type 630; C, 630 agrB1D1 mutant; D, 630 complemented agrB1D1 mutant; E, wild-type R20291; F, R20291 agrB1D1 mutant; G, complemented R20291 agrB1D1 mutant; H, R20291 agrB2D2 mutant.