Microbial production of testosterone and testololactone in the culture of Aspergillus terreus

Microbial endocrinology: the mechanisms by which the microbiota influences host sex steroids

Recent progress in microbial endocrinology has propelled this field from initially providing correlational links to defining the mechanisms by which microbes influence systemic sex hormones. Importantly, the interaction between the gut-resident bacteria and host-secreted hormones has been shown to be critical for host development as well as hormone-mediated disease progression. This review investigates how microbes affect active sex hormone levels, with a focus on gut-associated bacteria hormonal modifications and the resulting host physiological status. Specifically, we focus on the ability of the microbiota to reactivate estrogens and deactivate androgens and thereby influence systemic levels of host hormones in a clinically significant manner.

Biotransformation of Androstenedione by Filamentous Fungi Isolated from Cultural Heritage Sites in the State Tretyakov Gallery

Simple Summary

Microorganisms are able to grow on substrates of the most diverse nature. One of the most practical habitats, in terms of cultural heritage conservation, is fine art objects such as tempera or oil paintings on canvas. Since tempera paints are produced on the basis of egg yolk, which is one of the richest sources of cholesterol in nature (up to 2% of dry weight), and in the process of aging of tempera materials, changes in cholesterol do not affect the core structure of the steroid nucleus, the group of fungi that we have isolated are tempera painting destructors is seen as a promising object for screening for their possible steroid-transforming activities. In this regard, the purpose of our work was to determine the ability to transform pharmaceutically significant steroids with dominant fungi-destructors of tempera paintings, previously isolated in the State Tretyakov Gallery. Consequently, we have demonstrated for the first time that fungi-destructors of tempera paintings have steroid-transforming activity and are promising microorganisms for screening for biotechnologically significant transformations of steroids with further industrial use.

Abstract

The transformation of steroids by microorganisms is widely used in medical biotechnology. A huge group of filamentous fungi is one of the most promising taxa for screening new biocatalytic reactions in order to obtain pharmaceutically significant steroids. In this work, we screened 10 filamentous fungi-destructors of egg tempera for the ability to biotransform androst-4-en-3,17-dione (AD) during cultivation in a liquid nutrient medium or in a buffer solution. These taxonomically unrelated strains, belonging to the classes Eurotiomycetes, Dothideomycetes and Sordariomycetes, are dominant representatives of the microbiome from halls where works of tempera painting are stored in the State Tretyakov Gallery (STG, Moscow, Russia). Since the binder of tempera paints, egg yolk, contains about 2% cholesterol, these degrading fungi appear to be a promising group for screening for steroid converting activity. It turned out that all the studied fungi-destructors are able to transform AD. Some strains showed transformation efficiency close to the industrial strain Curvularia lunata RNCIM F-981. In total, 33 steroids formed during the transformation of AD were characterized, for 19 of them the structure was established by gas chromatography/mass spectrometry analysis. In this work, we have shown for the first time that fungi-destructors of tempera paintings can efficiently transform steroids.

Production aspects of testosterone by microbial biotransformation and future prospects

In human males, TS plays a key role in maintaining health and sexual functioning. Cholesterol acts as a precursor molecule for its biosynthesis. The microbial biotransformation of cholesterol by numerous microbes like bacteria, fungi, yeasts, etc. has led to the synthesis of TS out of human body making it a great example for industrial steroid production due to its therapeutic properties. Biotransformation through microbes is more advantageous over chemical synthesis as it gives higher conversion rates, higher specificity; reaction goes under mild conditions like temperature and neutral pH, thus being an effective alternate to chemical route. Current review focuses on production aspects of TS by microbial biotransformation and its future prospects with recent advancement.

Biotransformation of androstenedione and androstadienedione by selected Ascomycota and Zygomycota fungal strains

Filamentous fungi is a huge phylum of lower eukaryotes with diverse activities towards various substrates, however, their biocatalytic potential towards steroids remains greatly underestimated. In this study, more than forty Ascomycota and Zygomycota fungal strains of 23 different genera were screened for the ability to catalyze structural modifications of 3-oxo-androstane steroids, - androst-4-ene-3,17-dione (AD) and androsta-1,4-diene-3,17-dione (ADD). Previously unexplored for these purposes strains of Absidia, Acremonium, Beauveria, Cunninghamella, Doratomyces, Drechslera, Fusarium, Gibberella genera were revealed capable of producing in a good yield valuable 7α-, 7β-, 11α- and 14α-hydroxylated derivatives, as well as 17β-reduced and 1(2)-dehydrogenated androstanes. The bioconversion routes of AD and ADD were proposed based on the key intermediates identification and time courses of the bioprocesses. Six ascomycete strains were discovered to provide effective 7β-hydroxylation of ADD which has not been so far reported. The structures of major products and intermediates were confirmed by HPLC, mass-spectrometry (MS), ¹H and ¹³C NMR analyses. The results contribute to the knowledge on the functional diversity of steroid-transforming filamentous fungi. Previously unexplored fungal biocatalysts capable of effective performing structural modification of AD and ADD can be applied for industrial bioprocesses of new generation.

Metabolic fate of pregnene-based steroids in the lactonization pathway of multifunctional strain Penicillium lanosocoeruleum

Background

Metabolic activities of microorganisms to modify the chemical structures of organic compounds became an effective tool for the production of high-valued steroidal drugs or their precursors. Currently research efforts in production of steroids of pharmaceutical interest are focused on either optimization of existing processes or identification of novel potentially useful bioconversions. Previous studies demonstrated that P. lanosocoeruleum KCH 3012 metabolizes androstanes to the corresponding lactones with high yield. In order to explore more thoroughly the factors determining steroid metabolism by this organism, the current study was initiated to delineate the specificity of this fungus with respect to the cleavage of steroid side chain of progesterone and pregnenolone The effect of substituents at C-16 in 16-dehydropregnenolone, 16α,17α-epoxy-pregnenolone and 16α-methoxy-pregnenolone on the pattern of metabolic processing of these steroids was also investigated.

Results and discussion

All of the analogues tested (except the last of the listed) in multi-step transformations underwent the Baeyer–Villiger oxidation to their δ-d-lactones. The activity of 3β-HSD was a factor affecting the composition of the product mixtures. 16α,17α-epoxy-pregnenolone underwent a rare epoxide opening with retention stereochemistry to give four 16α-hydroxy-lactones. Apart from oxidative transformations, a reductive pathway was revealed with the unique hydrogenation of 5-ene double bond leading to the formation of 3β,16α-dihydroxy-17a-oxa-d-homo-5α-androstan-17-one. 16α-Methoxy-pregnenolone was transformed to the 20(R)-alcohol with no further conversion.

Conclusions

This work clearly demonstrated that P. lanosocoeruleum KCH 3012 has great multi-functional catalytic properties towards the pregnane-type steroids. Studies have highlighted that a slight modification of the d-ring of substrates may control metabolic fate either into the lactonization or reductive and oxidative pathways. Possibility of epoxide opening by enzymes from this microorganism affords a unique opportunity for generation of novel bioactive steroids.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-0948-1) contains supplementary material, which is available to authorized users.

Biotransformation of dehydro-epi-androsterone by Aspergillus parasiticus: Metabolic evidences of BVMO activity

The research on the synthesis of steroids and its derivatives is of high interest due to their clinical applications. A particular focus is given to molecules bearing a D-ring lactone like testolactone because of its bioactivity. The Aspergillus genus has been used to perform steroid biotransformations since it offers a toolbox of redox enzymes. In this work, the use of growing cells of Aspergillus parasiticus to study the bioconversion of dehydro-epi-androsterone (DHEA) is described, emphasizing the metabolic steps leading to D-ring lactonization products. It was observed that A. parasiticus is not only capable of transforming bicyclo[3.2.0]hept-2-en-6-one, the standard Baeyer-Villiger monooxygenase (BVMO) substrate, but also yielded testololactone and the homo-lactone 3β-hydroxy-17a-oxa-D-homoandrost-5-en-17-one from DHEA. Moreover, the biocatalyst degraded the lateral chain of cortisone by an oxidative route suggesting the action of a BVMO, thus providing enough metabolic evidences denoting the presence of BVMO activity in A. parasiticus. Furthermore, since excellent biotransformation rates were observed, A. parasiticus is a promising candidate for the production of bioactive lactone-based compounds of steroidal origin in larger scales.

Baeyer-Villiger oxidation of some C(19) steroids by Penicillium lanosocoeruleum

The biotransformation of androsterone (1), epiandrosterone (2), androstanedione (3) and DHEA (dehydroepiandrosterone) (4) by Penicillium lanosocoeruleum-a fungal species not used in biotransformations so far-were described. All the substrates were converted in high yield (70%-99%) into D ring δ-lactones. The oxidation of 1 produced 3α-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (5). The oxidation of 2 led to 3β-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (6). The biotransformation of 3 resulted in the formation of 3α-hydroxy-17a-oxa-D-homo-5α-androstan-17-one (5) and 17a-oxa-D-homo-5α-androstan-3,17-dione (7). An analysis of the transformation progress of the studied substrates as a function of time indicates that the Baeyer-Villiger monooxygenase of this fungus does not accept the 3β-hydroxy-5-ene functionality of steroids. In this microorganism steroidal 3β-hydroxy-dehydrogenase (3β-HSD) was active, and as a result DHEA (4) was transformed exclusively to testololactone (8). Apart from the observed oxidative transformations, a reductive pathway was revealed with the C-3 ketone being reduced to a C-3α-alcohol. It is demonstrated for the first time that the reduction of the 3-keto group of the steroid nucleus can occur in the presence of a ring-D lactone functionality.

Biotransformation of some steroids by Aspergillus terreus MRC 200365

The biotransformations of testosterone, epiandrosterone, progesterone and pregnenolone byAspergillus terreusMRC 200365 for five days were described. The biotransformation of testosterone afforded testolactone. The biotransformation of epiandrosterone afforded 3β-hydroxy-17a-oxa-D-homo-5α-androstan-17-one. The biotransformation of progesterone afforded androst-4-ene-3,17-dione and testolactone. The biotransformation of pregnenolone afforded 3β-hydroxy-17a-oxa-D-homoandrost-5-en-17-one and testolactone.

Studies on the microbial transformation of androst-1,4-dien-3,17-dione with Acremonium strictum

The strain of Acremonium strictum PTCC 5282 was applied to investigate the biotransformation of androst-1,4-dien-3,17-dione (I; ADD). Microbial products obtained were purified by preparative TLC and the pure metabolites were characterized on the basis of their spectroscopic features (13C NMR, 1H NMR, FTIR, MS) and physical constants (melting points and optical rotations). The 15 alpha-Hydroxyandrost-1,4-dien-3,17-dione (II), 17 beta-hydroxyandrost-1,4-dien-3-one (III), androst-4-en-3,17-dione (IV; AD), 15 alpha-hydroxyandrost-4-en-3,17-dione (V), 15 alpha,17 beta-dihydroxyandrost-1,4-dien-3-one (VI) and testosterone (VII) were produced during this fermentation. Formation of the 15 alpha,17 beta-dihydroxy derivative of ADD is reported for the first time during steroid biotransformation. The bioconversion reactions observed were 1,2-hydrogenation, 15 alpha-hydroxylation and 17-ketone reduction. From the time course profile of this biotransformation, ketone reduction and 1,2-hydrogenation were observed from the first day of fermentation while 15 alpha-hydroxylation occurred from the third day. Optimum concentration of the substrate, which gave the maximum bioconversion efficiency, was 0.5 mg ml(-1) in one batch. The highest yield of the microbial products recorded in this work was achieved within the pH range 6.5-7.3 and at the temperature of 27 degrees C.