Susceptibility of bacitracin-treated and <i>vraDE</i>-overexpressing <i>S. aureus</i> to nisin A and nukacin ISK-1.

Expression of braR, graR, vraR, braA, vraD, and vraF was determined using the method described in the Materials and Methods. (A) braA, vraF, vraD, braR, graR, and vraR expression in S. aureus MW2 exposed to various concentrations of nisin A (5 min exposure). *, statistically significant difference from the wild-type as tested using Dunnett’s method (p<0.05). (B) Time course experiment of braA, vraF, and vraD expression in S. aureus MW2 exposed to nisin A (16 µg/ml). (C) braA, vraF, and vraD expression in S. aureus MW2 and three mutants (braRS, graRS, and vraSR mutant) exposed to nisin A (16 µg/ml). *, statistically significant difference from the wild-type as tested using Dunnett’s method (p<0.05).