Microbiological transformation of Reichstein's Substans S (I) to 17α, 20β, 21-trihydroxy-1, 4-pregnadien-3-one (II) and 17α, 21-dihydroxy-1, 4-pregnadiene-3, 20-dione (III) by the action of Pseudomonas sp. 125, and to 17α, 20β, 21-trihydroxy-4-pregnen-3-one (IV) by Pseudomonas sp. M8 was described.
