ABSTRACT
The conditions for a directed biocatalytic oxidation of beta-sitosterol to a pharmacologically promising stigmast-4-en-3-one using Rhodococcus actinobacteria were selected. It was shown that palmitic acid induced the cholesterol oxidase reaction and allowed for the decrease in the bioconversion process duration from 7 to 5 days. The maximum level ofstigmast-4-ene-3-one formation was achieved using n-hexadecane as an additional growth substrate. With increased concentrations of beta-sitosterol (up to 2 g/L) an effective target product formation (80%) was achieved in the presence of Tween-80 and beta-cyclodextrine. R. erythropolis strains were 1.5-2 times more active than R. ruber strains in catalyzing the beta-sitosterol biotransformation process.
Subject(s)
Biocatalysis , Rhodococcus/metabolism , Sitosterols/metabolism , Stigmasterol/analogs & derivatives , Alkanes/chemistry , Biotransformation , Cholesterol Oxidase/chemistry , Cholesterol Oxidase/metabolism , Sitosterols/chemistry , Stigmasterol/chemical synthesisABSTRACT
The ability of pure cultures of Rhodococcus actinobacteria from the Ural specialized collection of alkanotrophic microorganisms (World Federation for Culture Collections accession number 768; http://www.ecology.psu.ru/iegmcol) to convert beta-sitosterol (BSS) and its 3beta-acylated derivatives was studied. Rhodococcus strains with pronounced cholesterol oxidase activity, capable of converting BSS to stigmat-4-ene-3-one in the reaction of cooxidation with n-hexadecane, were selected. The dependence of the activity of cholesterol oxidase of rhodococci on the length of the acyl group in BSS esters was studied. Conditions under which Rhodococcus cells convert BSS to 17beta-hydroxyandrost-4-ene-3-one (testosterone), commonly used in pharmacology, were determined.
