Patent ID: 7416866

Claim:
A process for selective introduction of a double bond into ring A of a steroid skeleton by overexpression of 3-keto steroid-Δ 1 -dehydrogenases , wherein a) a Δ 1 -dehydrogenase gene encoding a polypeptide comprising Seq. ID No. 11 is isolated from Bacillus sphaericus , cloned and amplified, b) promoter and terminator elements of the 3-keto steroid-Δ 1 -dehydrogenase gene or other promoter and terminator elements are isolated from the same or another bacterium, cloned and amplified, c) expression plasmids are constructed in which the 3-keto steroid-Δ 1 -dehydrogenase gene from a), is flanked by promoter and terminator sequences of the 3-keto steroid-Δ 1 -dehydrogenase gene or by other promoter and terminator elements from b), is contained, d) B. sphaericus, B. subtilis , or E. coli host bacteria are transformed with the expression plasmid that is produced under c), and e) the thus produced bacteria are cultivated, and the selective dehydrogenation at 1-position in the steroid skeleton of hydrocortisone (F), hydrocortisone-17-acetate (MAF), hydrocortisone-21-acetate (EAF), 4-androstene-3-17-dione(AD), fluocortolone A acetate (FCAA) or 11β,17α-Dihydroxy-6α,9α-difluoro-16α-methylprogesterone (DDFMP) is performed with these cultures, whereby i) a high substrate concentration at unaltered operating times is used, and ii) no disruptive secondary zones are produced.