Genome-Wide Transcriptome Profiling Provides Insight on Cholesterol and Lithocholate Degradation Mechanisms in Nocardioides simplex VKM Ac-2033D.

Steroid microbial degradation plays a significant ecological role for biomass decomposition and removal/detoxification of steroid pollutants. In this study, the initial steps of cholesterol degradation and lithocholate bioconversion by a strain with enhanced 3-ketosteroid dehydrogenase (3-KSD) activity, Nocardioides simplex VKM Ac-2033D, were studied. Biochemical, transcriptomic, and bioinformatic approaches were used. Among the intermediates of sterol sidechain oxidation cholest-5-en-26-oic acid and 3-oxo-cholesta-1,4-dien-26-oic acid were identified as those that have not been earlier reported for N. simplex and related species. The transcriptomic approach revealed candidate genes of cholesterol and lithocholic acid (LCA) catabolism by the strain. A separate set of genes combined in cluster and additional 3-ketosteroid Δ1-dehydrogenase and 3-ketosteroid 9α-hydroxylases that might be involved in LCA catabolism were predicted. Bioinformatic calculations based on transcriptomic data showed the existence of a previously unknown transcription factor, which regulates cholate catabolism gene orthologs. The results contribute to the knowledge on diversity of steroid catabolism regulation in actinobacteria and might be used at the engineering of microbial catalysts for ecological and industrial biotechnology.

Draft Genome Sequence of the Moderately Thermophilic Actinobacterial Steroid-Transforming Saccharopolyspora hirsuta subsp. hirsuta Strain VKM Ac-666T.

The draft genome sequence of the type strain Saccharopolyspora hirsuta subsp. hirsuta VKM Ac-666 was sequenced. This moderately thermophilic actinobacterial strain of sugarcane bagasse origin is able to transform different steroid substrates.

Synthesis of 3beta-hydroxy-androsta-5,7-dien-17-one from 3beta-hydroxyandrost-5-en-17-one via microbial 7alpha-hydroxylation.

The synthesis of 3beta-hydroxy-androsta-5,7-dien-17-one from 3beta-hydroxy-androst-5-en-17-one (dehydroepiandrosterone, DHEA) via microbial 7alpha-hydroxylation has been accomplished. At the first stage, 3beta,7alpha-dihydroxy-androst-5-en-17-one was obtained in high yield (71.2%) using a strain of Gibberella zeae VKM F-2600, which was first applied for DHEA conversion. The further route included the substitution of 7alpha-hydroxyl group with chlorine followed by a dehydrochlorination stage, and required minimal purifications of the intermediate products. The steroids obtained at every step were characterized by TLC,1H NMR, MS, UV- and IR-spectrometry. The combination of microbial and chemical steps ensured 54.6% yield of the target 3beta-hydroxy-androsta-5,7-dien-17-one from DHEA and can be applied for obtaining novel vitamin D derivatives.

Hydroxylation of carbazoles by Aspergillus flavus VKM F-1024.

Carbazole was metabolized by Aspergillus flavus VKM F-1024 forming few monohydroxylated products. The structure of metabolites was determined by TLC, GC, MS and (1)H NMR analyses. 3-Hydroxycarbazole was revealed as a major bioconversion product, 1-hydroxy- and 2-hydroxycarbazoles were observed as minor products. In the presence of 1-benzoylindole, the hydroxylation position shifted toward preferable accumulation of 2-hydroxycarbazole and the formation of 2,6- and 2,7-dihydroxycarbazoles. This effect and microbial formation of these metabolites have never been reported before. At the conversion of N-acetyl- and N-benzoylcarbazoles, carbazole was the major product, while 1-, 2- and 3-monohydroxycarbazoles were formed in small amounts.