Summary of B. subtilis colony-spreading mutants isolated from strain 3610

Genotype (reason for colony-spreading defect, if any)StrainGeneration time in CMK broth (min)aStationary phase OD600a,dSurfactin concn (μg ml−1)a,b
Wild type3610247.24932
Class I (lack of surfactin)
Class IIa (reduced growth rate or yield)
with 1 mM uracil804.79548
Class IIb (medium acidification and toxicity)
Class IIc (potassium transport limitation)
  • a Averages of duplicate determinations in CMK broth determinations.

  • b Surfactin determinations of the cell-free media using authentic surfactin to generate a standard curve by the drop collapse method. These values were determined by dilution with CMK broth, and those with an asterisk were indistinguishable from the background activity. The onset of surfactin release to the medium varied considerably between strains but occurred in early stationary phase. All values, measured in late stationary stage, are averages of duplicate determinations with a variation of <15%.

  • c Growth occurred in CMK broth as it contains 14 mM K+ (7 mM K2HPO4).

  • d OD600, optical density at 600 nm.