[Lipid composition of a Corynebacterium mediolanum culture transforming steroids].

Lipid composition was studied in Corynebacterium mediolanum during its growth in complex organic media favouring a high transformation activity. Lipid composition of the media was also analyzed. Lipid composition of the culture grown in a synthetic medium was comparatively studied. C. mediolanum was shown to have a peculiar lipid spectrum which did not depend on the growth medium composition and whose main component was an unidentified glycolipid (60-80% of the total lipid content). The lipids of the culture included also phosphatidyl glycerol, diphosphatidyl glycerol, a minor unidentified glycolipid, mono-, di- and triglycerides, free fatty acids, hydrocarbons and, in trace amounts, sterols and their esters. The fatty acids were represented mainly by anteiso-C15, iso-C16 and anteiso-C17. The total lipid content varied from 3 to 6% of the dry biomass weight depending on the growth phase. A correlation was established between a change in the lipid content of C. mediolanum (in particular, phosphatidyl glycerol) and its transformation activity. The lipids present in the media were found to inhibit the transformation of 21-acetate 3 beta,17 alpha,21-trihydroxy-5-pregnenone-20 (monoacetate of substance R, MAR) into the Reichstein substance S, 17 alpha,21-dihydroxy-4-pregnenedione-3,20 performed by the culture. The rate of MAR transformation by the growing culture rose when lipids were eliminated from the composition of organic media.