Process for oxidation of steroids and genetically engineered cells used therein

A process for the selective oxidation of a hydrocortisone precursor compound to an oxidized product which process comprises the steps of:

• (a) incubating the compound to be oxidized in the presence of a recombinant host cell or progeny thereof comprising at least one expression cassette comprising a heterologous DNA encoding two or more human or bovine enzymes from the metabolic pathway for the bioconversion of cholesterol to hydrocortisone wherein one of the enzymes catalyzes the oxidation of 17α-hydroxyprogesterone to cortexolone and the remaining one or more enzymes catalyze at least one reaction selected from the group consisting of:
• the oxidation of cholesterol to pregnenolone;
• the oxidation of pregnenolone to progesterone;
• the oxidation of progesterone to 17α-hydroxyprogesterone;
• and the oxidation of cortexolone to hydrocortisone;
• wherein the heterologous DNA is operably linked to control sequences required to express the encoded enzymes in a recombinant host wherein the host is a species of Saccharomyces, Kluyveromyces or Escherichia coli and wherein the incubation is performed under conditions where the compound is oxidized and oxidized product accumulates, and (b) recovering the oxidized product.