pH regulation of penicillin production in Aspergillus nidulans.

As shown by both bioassay and high-performance liquid chromatographic (HPLC) analysis, penicillin G production by Aspergillus nidulans is subject to regulation by the pH of the growth medium. Penicillin titres were highest at alkaline pH and in strains carrying mutations in the regulatory gene pacC which mimics the effects of growth at alkaline pH. They were lowest at acid pH and in strains carrying mutations in the palA, palB, palC, palE or palF genes which mimic the effects of growth at acid pH.