Isolation of mutants deregulated in phosphate control of candicidin biosynthesis

Mutants have been isolated in which phosphate does not inhibit the biosynthesis of candicidin. At high phosphate concentrations, candicidin production by phosphate-deregulated mutants is still inhibited, but to a lesser extent than in the wild type. Some of these mutants are higher candicidin producers than the wild type, not only in phosphate-supplemented medium but also in non-supplemented production medium. The high candicidin production by these mutants is due to (1) a high specific rate of candicidin biosynthesis and (2) an extended production phase. None of the phosphate-deregulated mutants in which uptake of [32P]phosphate was measured was a phosphate-permeability mutant.