Studies on Bacillus stearothermophilus. Part II. Transformation of progesterone

Occurrence and mass balance of sixty-two progestins in a municipal sewage treatment plant

Progestins (PGs) are a group of steroid hormones known to have endocrine-disrupting effects. These compounds can enter the aquatic environment via the discharge of treated or untreated wastewater and the disposal of sludge from sewage treatment plants (STPs); thus, their removal in STPs are of great importance. The present study simultaneously investigated the occurrences and fates of 62 PGs in a municipal STP in Beijing, China. Progesterone (P) and its metabolites were found to be the predominant compounds, with total dissolved concentrations of 1866 ng/L in the influent. About 11 P metabolites were newly detected, accounting for 25-55% and 75-91% of the total concentrations in wastewater and sludge, respectively. For the other three groups of PGs derived from different parent compounds, P derivatives were first detected in the STP with the highest concentration in the wastewater and sludge, followed by 19-nortestosterone (NT) derivatives and 17α-hydroxyprogesterone (17α-OHP) derivatives. The removal efficiencies in the dissolved phase of wastewater were relatively high for P and its metabolites (95-99%) and P derivatives (91-99%). And the relative persistence of NT (68-99%) and 17α-OHP derivatives (79-99%) was observed during the wastewater treatment processes. Mass balance analysis showed that the lost mass proportions were as high as 41-99%, the mass fractions in sludge were in the range of 0-55%, and 0.24-25% of the initial mass loadings was present in the effluent. These results indicated that biodegradation was the major removal mechanism of PGs in the STP.

Degradation of norgestrel by bacteria from activated sludge: comparison to progesterone

Natural and synthetic progestagens in the environment have become a concern due to their adverse effects on aquatic organisms. Laboratory studies were performed to investigate aerobic biodegradation of norgestrel by bacteria from activated sludge in comparison with progesterone, and to identify their degradation products and biotransformation pathways. The degradation of norgestrel followed first order reaction kinetics (T1/2 = 12.5 d), while progesterone followed zero order reaction kinetics (T1/2 = 4.3 h). Four and eight degradation products were identified for norgestrel and progesterone, respectively. Six norgestrel-degrading bacterial strains (Enterobacter ludwigii, Aeromonas hydrophila subsp. dhakensis, Pseudomonas monteilii, Comamonas testosteroni, Exiguobacterium acetylicum, and Chryseobacterium indologenes) and one progesterone-degrading bacterial strain (Comamonas testosteroni) were successfully isolated from the enrichment culture inoculated with aerobic activated sludge. To our best knowledge, this is the first report on the biodegradation products and degrading bacteria for norgestrel under aerobic conditions.

Tryptophan oxidative metabolism catalyzed by geobacillus stearothermophilus: a thermophile isolated from kuwait soil contaminated with petroleum hydrocarbons

Tryptophan metabolism has been extensively studied in humans as well as in soil. Its metabolism takes place mainly through kynurenine pathway yielding hydroxylated, deaminated and many other products of physiological significance. However, tryptophan metabolism has not been studied in an isolated thermophilic bacterium. Geobacillus stearothermophilus is a local thermophile isolated from Kuwait desert soil contaminated with petroleum hydrocarbons. The bacterium grows well at 65 °C in 0.05 M phosphate buffer (pH 7), when supplied with organic compounds as a carbon source and has a good potential for transformation of steroids and related molecules. In the present study, we used tryptophan ethyl ester as a carbon source for the bacterium to study the catabolism of the amino acid at pH 5 and pH 7. In this endeavor, we have resolved twenty one transformation products of tryptophan by GC/LC and have identified them through their mass spectral fragmentation.

Modification of progesterone and testosterone by a food-borne thermophile Geobacillus kaustophilus

The present work was carried out to study structural modification of steroids by Geobacillus kaustophilus, a bacterial thermophile present in milk and the environment. Incubation of progesterone and testosterone with G. kaustophilus at 65 degrees C resulted in oxygenated steroid nuclei. The oxygenation of the steroid molecule was stereo specific. Seven metabolites of progesterone horizontal line 6beta/6alpha-hydroxytestosterone, 20-hydroxyprogesterone, 6beta-/6alpha-20-dihydroxyprogesterone, 5alpha-pregnane-3,6,20-trione, and 3beta-hydroxy-5alpha-pregnane-6,20-dione horizontal line were identified. Four compounds horizontal line namely, 66-/6--hydroxytestosterone and 6beta/6alpha-hydroxyandrostenedione horizontal line and androst-4-en-3,17-dione were identified as testosterone metabolites. This shows that G. kaustophilus is capable of modifying steroid nuclei at elevated temperatures. G. kaustophilus is a stable thermophile first isolated from milk. Our results show that endogenous steroids present in milk can be modified by G. kaustophilus, causing detrimental effect on human health.

Antioxidant activity of biotransformed sex hormones facilitated by Bacillus stearothermophilus

Bacillus stearothermophilus, a thermophilic bacterium isolated from Kuwaiti desert, when incubated with exogenous progesterone for 10 days at 65 degrees C produced two monohydroxylated, two dihydroxy isomers of progesterone and a B-Seco compound. These metabolites were purified by TLC and HPLC followed by their identification through (1)H, (13)C NMR and other spectroscopic data. Microbial hydroxylation of 17beta-estradiol resulted in the production of estrone. The effect of some inducers resulted in the production of two metabolites from 17beta-estradiol one of which was identified as 3,6beta,17beta-trihydroxyestra-1,3,5,14(10)-tetrene and the other metabolite remained unidentified. The transformation products were identified through their spectral data and comparison with reference to compounds. Antioxidant activities of progesterone transformed mixture and purified metabolites of 17beta-estradiol were studied by linoleic acid/beta-carotene assay. An enhanced antioxidant activity for progesterone transformation products was observed, when compared to progesterone. A comparison of antioxidant activity of progesterone and 17beta-estradiol transformation products is reported.

Antioxidant activity of biotransformed sex hormones facilitated by Bacillus stearothermophilus

Bacillus stearothermophilus, a thermophilic bacterium isolated from Kuwaiti desert, when incubated with exogenous progesterone for 10 days at 65 degrees C produced two monohydroxylated, two dihydroxy isomers of progesterone and a B-Seco compound. These metabolites were purified by TLC and HPLC followed by their identification through (1)H, (13)C NMR and other spectroscopic data. Microbial hydroxylation of 17beta-estradiol resulted in the production of estrone. The effect of some inducers resulted in the production of two metabolites from 17beta-estradiol, one of which was identified as 3,6beta,17beta-trihydroxyestra-1,3,5,14(10)-tetrene and the other metabolite remains unidentified. The transformation products were identified through their spectral data and comparison with reference compounds. Antioxidant activities of progesterone transformed mixture and purified metabolites of 17beta-estradiol were studied by linoleic acid/beta-carotene assay. An enhanced antioxidant activity for progesterone transformation products was observed when compared to progesterone. A comparison of antioxidant activity of progesterone and 17beta-estradiol transformation products is reported.

Predominant allylic hydroxylation at carbons 6 and 7 of 4 and 5-ene functionalized steroids by the thermophilic fungus Rhizomucor tauricus IMI23312

This paper demonstrates for the first time transformation of a series of steroids (progesterone, androst-4-en-3,17-dione, testosterone, pregnenolone and dehydroepiandrosterone) by the thermophilic fungus Rhizomucor tauricus. All transformations were found to be oxidative (monohydroxylation and dihydroxylation) with allylic hydroxylation the predominant route of attack functionalizing the steroidal skeleta. Timed experiments demonstrated that dihydroxylation of progesterone, androst-4-en-3,17-dione and pregnenolone all initiated with hydroxylation on ring-B followed by attack on ring-C. Similar patterns of steroidal transformation to those observed with R. tauricus have been observed with some species of thermophilic Bacilli and mesophilic fungi. All metabolites were isolated by column chromatography and were identified by (1)H, (13)C NMR, DEPT analysis and other spectroscopic data. The application of thermophilic fungi to steroid transformation may represent a potentially rich source for the generation of new steroidal compounds as well as for uncovering inter and intraspecies similarities and differences in steroid metabolism.

Biotransformation of cycloartane-type triterpenes by the fungus Glomerella fusarioides

Biotransformation of three cycloartane-type triterpenes, cycloartenol (1), 24-methylenecycloartanol (2), and cycloartenone (3), by the fungus Glomerella fusarioides was studied. Compound 1 was converted to 3, cycloart-25-ene-3beta,24-diol (4), and cycloartane-3beta,24,25-triol (5). Compound 2 was metabolized to cycloeucalenol (6) and two new compounds, 24-methylcycloartane-3beta,24,24(1)-triol (7) and 24(1)-methoxy-24-methylcycloartane-3beta,24-diol (8). Compound 3 was converted into two new metabolites, 4alpha,4beta,14alpha-trimethyl-9beta,19-cyclopregnane-3,20-dione (9) and 25-hydroxy-24-methoxycycloartan-3-one (14), and four known compounds, viz., cycloartane-3,24-dione (10), 24-hydroxycycloart-25-en-3-one (11), (23E)-25-hydroxycycloart-23-en-3-one (12), and 24,25-dihydroxycycloartan-3-one (13). The structures of four new metabolites, 7, 8, 9, and 14, were established by spectroscopic methods.

Studies on Bacillus stearothermophilus. Part IV. Influence of enhancers on biotransformation of testosterone

The impact of chemical enhancers on the biotransformation of testosterone has been exploited. Application of crude cell concentrates to produce Bacillus stearothermophilus-mediated bioconversion of testosterone at 65 degrees C for 72 h has been examined. After incubation, the xenobiotic substrate was added to the concentrated whole cell suspensions. The enhancer molecules were included in the whole cell suspension. The resultant products, after extraction into an organic solvent, were purified by thin layer chromatography and identification was carried out through spectroscopic data. Five steroid metabolites 9,10-seco-4-androstene-3,9,17-trione, 5alpha-androstan-3,6,17-trione, 17beta-hydroxy-5alpha-androstan-3,6-dione, 3beta,17beta-dihydroxyandrost-4-ene-6-one and 17beta-hydroxyandrost-4,6-diene-3-one were identified as biotransformation products of testosterone. A possible biosynthetic route for these bioconversion products is postulated.