Metabolism of sterols by anaerobic Saccharomyces cerevisiae

Anaerobically grown Saccharomyces cerevisiae retained the ability to transfer a C 1 ‐group to the C‐24 position of a Δ 24(25) ‐sterol and to reduce the Δ 24(28) ‐bond of a 24‐methylenesterol. Both desmosterol and 24‐methylenecholesterol yielded 24β‐methylcholesterol. However, when the substituent at C‐24 was enlarged to a 24‐ethylidene group (fucosterol), reduction of the Δ 24(28) ‐bond did not occur. In no cases was a Δ 7 a Δ 22 ‐bond introduced. Because the Δ 24(28) ‐bond was, reduced in the absence of the Δ 22 ‐bond the Δ 22 is not an obligatory requirement for reduction.