Microbiological Oxidation of Sterols

Abstract

IN an earlier communication¹ we stated that by cultivating Proactinomyces roseus in a synthetic culture medium in which the only source of carbon and nitrogen was 2 per mille pyridine, and using up the superfluous nitrogen by emulsifying 0·1 per cent cholesterol in the medium and aerating it at 34° C., in two weeks we obtained 7-oxycholesterol and 4,5-cholestonone. Later, we received a letter from Dr. G. A. D. Haslewood, of the Physiological Laboratory, Guy's Hospital, London, S.E., expressing doubt that the occurrence of 7-oxycholesterol was the result of the microbiological oxidation; in his opinion, the result was analogous to the production of 7-oxycholesterol from cholesterol in alkali medium, by aeration and elevated temperature, as shown by Bergström and Wintersteiner^2,3, in which case the micro-organism plays no part.