Bioconversion of compactin to pravastatin by Actinomadura sp. ATCC 55678

The screening of known and unidentified actinomycetes revealed three strains which could hydroxylate compactin to pravastatin. The best was a new culture identified as Actinomadura sp. (ATCC 55678). Actinomadura sp. effectively converted compactin to pravastatin. The degree of conversion by cells was 65–78% of compactin added and 65–88% of compactin taken up, depending on the concentration of compactin and duration of the experiment. Increasing the compactin concentration resulted in a higher final pravastatin concentration especially when compactin was added intermittently. The conversion was linear for 16 h. The system required no induction with compactin. The hydroxylase in cell-free extracts of Actinomadura sp. converted compactin to pravastatin. It required NADPH as coenzyme and Mg2+ as cofactor; Mn2+ partially replaced Mg2+. In contrast to the inducible cytochrome P450 system of Streptomyces carbophilus which catalyzes the same overall reaction, this constitutive hydroxylase was stimulated by ATP and ascorbic acid and was not inactivated by CO. Actinomadura sp. required vitamins to support its growth. Addition of folic acid, thiamine and cyanocobalamin allowed growth in chemically defined medium. Cells grown in chemically defined medium were as capable of converting compactin to pravastatin as cells grown in complex medium.