[Effect of the steroid molecule structure on the direction of its hydroxylation by the fungus Curvularia lunata].

The main and side products of hydroxylation by the C. lunata VKPM F-981 mycelium of fourteen delta(4)-3-ketosteroids of the estrane, androstane, and pregnane series and six of their delta(5)-3beta-hydroxy analogues were identified by H1 PMR spectroscopy and comparison with standard samples. The obtained experimental data are considered in terms of the triangular model of the enzyme-substrate interaction. The dependence of the direction of hydroxylation of steroid molecules and the orientation of hydroxy groups on the structure of the initial substrate was revealed.

[Transformation of delta4-3-ketosteroids by free and immobilized cells of Rhodococcus erythropolis actinobacterium].

9alpha-Hydroxy derivatives were prepared from 11 steroids ofandrostane and pregnane series using Rhodococcus erythropolis VKPM Ac-1740 culture with 0.5-20 g/l substrate concentration in the reaction mixture. 9alpha-Monohydroxylation proceeded regardless of the substituent structure at C17. However, the structure of the steroid molecule influenced the time of complete conversion of the substrate and the yield of the transformation product. 9alpha-Hydroxy-androstenedione was obtained in 35 h in a yield of 85% when the maximum concentration of androstenedione (AD) was 10 g/l. 9alpha-Hydroxy-AD was also formed by the actinobacterium cells entrapped in poly(vinyl alcohol) cryogel beads. Nine successive transformation cycles were carried out using immobilized cells at 4.0 g/l concentration of AD in the medium. The yield of 9alpha-hydroxy-AD formed during six cycles (from two to eight with the duration of each cycle for 22-24 h) was 98%.

[Conversion of soybean sterols into 3,17-diketosteroids using actinobacteria Mycobacterium neoaurum, Pimelobacter simplex, and Rhodococcus erythropolis].

Abstract-Soybean sterols were converted into androst-4-ene-3,17-dione (AD) and 9alpha-hydroxyandrost-4-ene-3,17-dione (9-OH-AD) using three actinobacterium strains. The transformation of a microcrystallic substrate (particle size 5-15 nm) or the transformation in the presence of randomly methylated beta-cyclodextrin (MCD) were carried out by Mycobacterium neoaurum with a phytosterol load of 30 g/l over 144 h with an AD content of 14.5 and 15.2 g/l, respectively. AD obtained in the presence of MCD was transformed into ADD (13.5 g/l) by Pimelobacter simplex cells over 3 h and into 9-OH-AD by Rhodococcus erythropolis cells after 22 h without the isolation of AD from the cultural liquid. The technical product ADD was obtained in 75% yield, based on phytosterol. It contained as impurity 1.25% of AD and 1.5% of 1,2-dehydrotestosterone. In a control experiment-the process of 1,2-dehydrogenation of 20 g/l AD in the water solution of MCD-no by products were isolated. Thus, it is more expedient to introduce the 1,2-double bond into pure AD, whereas R. erythropolis strain with low destructive activity towards steroid nucleus can be used in the mixed culture with M. neoaurum. The crystal product contained, according to HPLC, 80% of 9-OH-AD, and 1.5 AD was combined. The yield of 9-OH-AD (m.p. 218-220 degrees C) based on transformed phytosterol was 56%.

[Hydroxylation of steroids by Curvalaria lunata mycelium in the presence of methyl-beta-cyclodextrine].

Transformation of 16 delta5-3beta-hydroxy- and delta4-3-ketosteroids of androstane and pregnane classes was carried out using Curvularia lunata mycelium suspended in phosphate buffer with methyl-beta-cyclodextrine (MCD). As the result, 20 monohydroxy- and dihydroxy-metabolites, whose structure was determined using specters of proton magnetic resonance and mass-specters, have been isolated. Hydroxylation of delta5-3beta-hydroxy-steroids occurred mostly in the C-7alpha position whereas hydroxylation of delta4-3-ketosteroids was in the C-11beta position. Only androst-4-en-3,17-dione, 9alpha-hydroxyl-androstenedione, and androsts-1,4-diene-3,17-dione were hydroxylated at C-14alpha position. Besides main 11beta-derivatives, the 6beta- and 7beta-hydroxy-derivatives with yield 10 and 30%, respectively, were isolated during transformation of progesterone and hydroxymethyl pregnadienon. The ratio of MCD to transforming steroid was 1 : 1 (mol/mol). Hydroxycortisone and 7alpha-hydroxyandrostenolone with the yield 55 and 77%, respectively, were obtained at the maximal concentrations of cortexolone 20 g/l and androstenolone acetate 10 g/l in the presence of MCD. Absorption of steroids on mycelium, lower speed of their transformation, low concentrations of modifying substrates, and low yield of hydroxyderivatives have been observed in the absence of MCD.

[The introduction of the 9alpha-hydroxy group into androst-4-en-3,17-dione using a new actinobacterium strain].

A 9alpha-hydrolase activity of a new actinobacterium strain identified as Rhodococcus erythropolis based on the analysis of a 16S rRNA gene sequence (1417 nucleotides) towards androst-4-en-3,17-dione (AD) was studied. In the presence of glucose in the medium, this strain completely transformed AD (4-20 g/l) into 9alpha-hydroxy-AD over 20-48 h. This culture was able to grow and perform AD 9alphahydroxylation at a concentration of dimethyl formamide up to 9%. Crystalline 9alpha-hydroxy-AD was isolated with a yield of over 90%.

[Conversion of phytosterols into androstenedione by Mycobacterium neoaurum].

Optimum conditions for transformation of phytosterols by Mycobacterium neoaururm, required for selective cleavage of the lateral chain into androstenedione, were shown to differ from the known conditions of animal sterol (cholesterol) transformation. Complete conversion of phytosterols into androstenedione at a substrate load of no less than 20 g/l was achieved on increasing the amount of the inoculum and the concentration of glucose (by 2 and 4 times, respectively, relative to cholesterol) and performing the fermentation under conditions of turbulent mixing. Under these conditions, both the rate of the transformation and the yield of the reaction product were high, due to the saturation of the culture liquid with hydrocarbonate. Data from the literature show that this ion is involved in cleavage of the branched lateral chain at carbon in position 24.

[Conversion of 17 alpha-methyltestosterone to methandrostenolone by the bacterium Pimelobacter simplex VKPM Ac-1632 with the presence of cyclodextrins].

Conditions of conversion of 17 alpha-methyltestosterone to methandrostenolone with the presence of modified beta-cyclodextrins (methylcyclodextrin, hydroxypropylcyclodextrin, and hydroxyethylcyclodextrin) in the steroid:cyclodextrin ratio 1:1 were studied. The experimental solutions of modified beta-cyclodextrins were prepared in deionized water with 5-7% methanol. Under the conditions found to be optimal, 1,2-dehydrogenation of 17 alpha-methyltestosterone was carried out with 2-4 g/l Pimelobacter simplex VKPM Ac-1632 biomass. At the substrate concentration 5-20 g/l, the reaction occurred for 1-15 h without any by-products. The maximum rate of methandrostenolone accumulation was observed with hydroxypropylcyclodextrin. The methylcyclodextrin solution can be reused for complete 17 alpha-methyltestosterone conversion at the concentration 5 g/l.

[Preparation of androsta-1,4-diene-3,17-dione from sterols using Mycobacterium neoaurum VKPM As-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.

[A study of steroid hydroxylation activity of Curvularia lunata mycelium].

It has been demonstrated that the mycelium of Curvularia lunata at the end of the logarithmic growth phase displays a maximal 11-hydroxylase activity towards cortexolone (4-6 g/l) used for transformation as a microcrystalline suspension in phosphate buffer. The mycelium at a later stage of fungal growth displays an elevated 14-hydroxylase activity, necessary for generation of 14-hydroxyandrostenedione. The effects of different forms of substrate added to the reaction mixture, age and concentration of mycelium, and fungal clones tolerant to salts of heavy metals (0.35-0.5%) were studied to remove the side 14-hydroxylation, accompanying the main cortexolone transformation. Mycelia of the fungal clones tolerant to Co2+ and Cu2+ displayed a weak hydroxylase activity or its complete absence and an elevated content of melanin, the biosynthesis of which is intensified under adverse conditions. The results obtained suggest that the transformation of steroids by the studied C. lunata strain is a detoxication of foreign compounds.

[Conversion of androstenedione and androstadienedione by sterol-degrading bacteria]. / Transformatsiia androstendiona i androstadiendiona bakteriiami degradiruiushchimi steriny.

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]. / Identifikatsiia novogo shtamma transformiruiushchikh steroidy mikobakterii kak 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.