Figure 2. Defining the boundaries of the antimycin gene cluster.

(A) Streptomyces albus S4 WT and mutant strains challenged with Candida albicans. Null mutants of genes adjacent to the gene cluster (coloured black in Fig. 1) produce an antimycin-positive phenotype, characterised by a large circular zone of cleared C. albicans growth. The ΔantC mutant strain displays an antimycin-negative phenotype, but retains residual antagonistic activity against C. albicans due to the production of candicidin, a second antifungal compound produced by this strain (Barke et al., 2010; Seipke et al., 2011a). (B) High-performance liquid chromatography (HPLC) of metabolites produced by S. albus S4 WT and mutant strains. The ΔantC mutant does not produce antimycins, while null mutations in genes adjacent to the antimycin cluster had no effect on antimycin production.