Formation of progesterone and 1-dehydroprogesterone from cholesterol in fermentation cultures of Mycobacterium aurum

The formation of progesterone and 1-dehydroprogesterone from cholesterol in fermentation cultures of Mycobacterium aurum ATCC 25790 was studied with the aim of clarifying the microbial pathway. The C22-intermediate (20S)-20-carboxy-1,4-pregnadien-3-one was microbiologically converted via the undetectable corresponding aldehyde into the C22-alcohol. However in the fermentation broth without microorganisms, but containing 2,2'-bipyridyl and copper ions, synthetically prepared C22-aldehyde was oxidized to the corresponding C21-compound 1-dehydroprogesterone, suggesting that the enzymatically originated C22-aldehydes may be immediately chemically oxidized to the corresponding C21-ketones.