COSYNTHESIS OF ERYTHROMYCIN A N-OXIDE BY MUTANTS OF SACCHAROPOLYSPORA-ERYTHRAEA BLOCKED IN ERYTHROMYCIN PRODUCTION

The production of erythromycin A (1) and free erythronolide B (2) in S accharopolyspora erythraea BTCC-2 is accompanied by formation of eryth romycin A N-oxide (3) and other minor components, the ratio of yields of 1 and 3 being 97:3. Erythromycin-blocked mutants of type I (impaire d in some unidentified steps prior to lactone synthesis) and type II ( accumulating only 2) cosynthesized both 1 and the accompanying metabol ites, but the ratio of 1 and 3 changed to 70:30. In pure cultures of t ype I, exogenous 2 was converted to 1 and minor components in ratios t ypical of the strain BTCC-2, whereas mutants of type II were effective convertors of 1 to 3.