Bioconversion of Methoxymethyl-Substituted Sterols by a Recombinant Mycolicobacterium smegmatis Strain: Optimization of Conditions for Pregnenolone Production
摘要
The co-expression of cytochrome P450scc (CYP11A1), adrenodoxin (Adx), and adrenodoxin reductase (AdR) from the bovine adrenal cortex in Mycolicibacterium smegmatis mc2 155 enables the production of the valuable pharmaceutical hormone pregnenolone from natural sterols. To prevent the formation of 3-oxosteroids, which hinder the efficient formation of the target product, 3-methoxymethyl (MOM) esters of cholesterol and phytosterol were used as substrates. By optimizing the time and method of substrate introduction, as well as the bioconversion conditions (aeration, molar ratio to solubilizer, the type and concentration of the additional carbon source, and the solvent), the yield of MOM-pregnenolone was increased up to 93% from 0.5 g/L MOM-cholesterol; the maximum titer was 3 g/L from 6 g/L of MOM-cholesterol (with three additions). The overall efficiency of the method for producing pregnenolone from cholesterol was 42 mol %. These results exceed the known literature data and can be used to develop biotechnology for the production of pregnenolone.