Fig. 3.

Increasing the extracellular potassium concentration abrogates the effects of surfactin. (A) Pellicle formation assay for surfactin-treated cells grown in LB in the absence or presence of 150 mM KCl. Pellicles and flow cytometry results are shown. (B) Specificity for extracellular potassium addition to counteract the effect of surfactin. To test the ion specificity of increasing the extracellular salt concentration supplemented to the LB growth medium, several other salts were tested in addition to KCl. The addition of NaCl or LiCl did not result in diminished biofilm formation. In contrast, other potassium salts (potassium phosphate and potassium acetate) had the same effect as KCl.