Preparation of androsta-1,4-diene-3,17-dione from sterols using Mycobacterium neoaurum VKPM Ac-1656 strain

A product of microbiological cleavage of the sterols side chain, androsta-1,4-diene-3,17-dione, is toxic for bacteria, in particular, actinobacteria of the genera Mycobacterium and Arthrobacter. Sterols were transformed into androsta-1,4-diene-3,17-dione by culturing the M. neoaurum VKPM An-1656 strain in a high yield, provided that a sorbent was used for elimination of contact between the bacterial cells and the product. Unlike the cholesterol side chain, the more branched chains of phytosterols were cleaved in the presence of M. neoaurum at a high rate only under turbulent stirring of the culture medium, which intensified the formation of hydrocarbonate ion from NaNI3 in situ.

[Conversion of androstenedione and androstadienedione by sterol-degrading bacteria]

The composition of steroid metabolites formed during the conversion of androstenedione and androstadienedione, products of degradation of sterol side chains by soil and mutant strains of the bacterial genera Mycobacterium and Protaminobacter, was studied. Testololactone was absent from the conversion products. This favors the idea of different cleavage pathways of steroid ring D in bacteria and fungi. Very small amounts of two new 14alpha-hydroxy derivatives with cleaved B ring were isolated after conversion of androstenedione by soil strains. It was shown that a mutant Mycobacterium smegmatis strain, as well as wild strains, could perform 14alpha-hydroxylation of steroids. It is suggested that cleavage of the steroid nucleus at the side of rings D and C starts with the introduction of a 14alpha-hydroxy group followed by dehydration.

[Identification of a new steroid transforming strain of mycobacteria as Mycobacterium neoaurum]

The ability to utilize sterols as a sole source of carbon was studied in 80 strains and consortia of hydrocarbon-oxidizing bacteria. One of the strains, which efficiently transformed both individual sterols and their mixtures, was identified as Mycobacterium neoaurum, based on the analysis of the sequence of the 16S rRNA gene.