Microbiological Transformation Research Articles

The Microbiological Transformation of Steroidal Saponins by Curvularia lunata.

Abstract The microbiological transformation of polyphyllin I (compound I ), polyphyllin III (compound II ), polyphyllin V (compound III ) and polyphyllin VI (compound IV ) by Curvularia lunata into their corresponding subsaponins, for example, diosgenin-3- O -α- l -arabinofuranosyl (1→4)-β- d -glucopyranoside (compound V ), diosgenin-3- O -α- l -rhamnopyranosyl (1→4)-β- d -glucopyranoside (compound VI ), diosgenin-3- O -β- d -glucopyranoside (compound VII ) and pennogenin-3- O -β- d -glucopyranoside (compound VIII ), were studied in this paper. Curvularia lunata is able to hydrolyze terminal rhamnosyls that are linked by 1→2 C– bond to sugar residues of steroidal saponins at C-3 position with high activity and regioselectivity.

In vitro biotransformation of an arsenosugar by mouse anaerobic cecal microflora and cecal tissue as examined using IC-ICP-MS and LC-ESI-MS/MS

This investigation examined chemical and microbiological transformations of an arsenosugar by mouse cecum. To mimic the low oxygen environment in the mammalian gastrointestinal tract, reaction mixtures were incubated under anaerobic conditions. An arsenosugar extracted from ribbon kelp, 3-[5'-deoxy-5-(dimethylarsinoyl)-beta-ribofuranosyloxy]-2-hydroxypropanesulfonic acid, As392, was added to reaction mixtures that contained either cecal microflora or cecal tissue homogenate. These reaction mixtures were incubated at 0 or 37 degrees C for up to 48 hours to monitor biotransformation of the arsenosugar. Analysis of the reaction mixtures by IC-ICP-MS and LC-ESI-MS/MS indicated that the arsenosugar was converted primarily (95%) to its sulfur analog in less than 1 h at 37 degrees C. Conversion of As392 to its sulfur analog was much slower at 0 degrees C (21% conversion after 48 h). In reaction mixtures with cecal tissue homogenate, conversion of As392 to its sulfur analog was slower (77% conversion after 48 h at 37 degrees C). A good mass balance was found in all reaction mixtures between the amount of arsenosugar added and the sum of all detected arsenic-containing products. LC-ESI-MS/MS spectra of the sulfur-containing arsenosugar formed in all reaction mixtures containing cecal microflora compared well with those of a synthetic standard. These results suggest that the anaerobic microflora of the gastrointestinal tract can rapidly convert ingested arsenosugars to sulfur analogs. This biotransformation may affect the subsequent absorption, metabolism, and disposition of arsenic present in arsenosugars.

The microbiological transformation of steroidal saponins by Curvularia lunata

The microbiological transformation of polyphyllin I (compound I), polyphyllin III (compound II), polyphyllin V (compound III) and polyphyllin VI (compound IV) by Curvularia lunata into their corresponding subsaponins, for example, diosgenin-3-O-α-l-arabinofuranosyl (1→4)-β-d-glucopyranoside (compound V), diosgenin-3-O-α-l-rhamnopyranosyl (1→4)-β-d-glucopyranoside (compound VI), diosgenin-3-O-β-d-glucopyranoside (compound VII) and pennogenin-3-O-β-d-glucopyranoside (compound VIII), were studied in this paper. Curvularia lunata is able to hydrolyze terminal rhamnosyls that are linked by 1→2 C– bond to sugar residues of steroidal saponins at C-3 position with high activity and regioselectivity.

Self-Purification of Water Current and the Role of Microbiological Transformation of Organic Matter in the System of the Selenga River and Its Delta

Self-Purification of Water Current and the Role of Microbiological Transformation of Organic Matter in the System of the Selenga River and Its Delta

Microbial Transformation of Curvularin

The microbiological transformation of curvularin (1) with Beauveria bassiana ATCC 7159 afforded three new metabolites identified as curvularin-7-O-beta-D-glucopyranoside (2), curvularin-4'-O-methyl-7-O-beta-D-glucopyranoside (3), and 6-hydroxycurvularin-4'-O-methyl-6-O-beta-D-glucopyranoside (4) resulting from hydroxylation, glucosidation, and methylglucosidation of the substrate. Isolation of 6-methyl-2,4-dihydroxyphenyl-4'-O-methyl-1-O-beta-D-glucopyranoside (5) from the fermentation broth of B. bassiana ATCC 7159 without any added substrate suggested that hydroxylase, glucosyl transferase, and methylase are constitutive enzymes of this organism.

Groundwater contamination by chlorinated naphthalenes and related substances caused by activities of a former military base

Water samples derived from two different aquifer layers of six sampling sites were analysed by GC/MS in order to characterize a groundwater contamination caused by chemicals used for wood impregnation. Mono- and dichlorinated naphthalenes, chlorobenzo( b)thiophene, 1-chloro-4-naphthol, 1-chloronaphthoic acid, acenaphthene and methyled naphthalenes were identified as the main pollutants and quantified. 1-Chloro-4-naphthol and 1-chloronaphthoic acid are discussed as possible indicators for anaerobic degradation processes. Results of inorganic and compound specific stable carbon isotope analyses revealed only a minor degree of microbiological transformation. Thus, sorption was characterized as the main attenuation process within the aquifer affecting the contamination described.

Biotransformation of 7-oxo- ent-kaur-16-ene derivatives by Gibberella fujikuroi

The microbiological transformation of 7-oxo- ent-kaur-16-ene by the fungus Gibberella fujikuroi gave fujenoic acid as the main compound, whilst the incubation of 18-hydroxy-7-oxo- ent-kaur-16-ene and 3α,18-dihydroxy-7-oxo- ent-kaur-16-ene afforded the corresponding 6β-hydroxy-derivatives. These facts indicate that the formation of fujenoic acid in this biotransformation should occur via a 7-oxo-6β-hydroxy derivative. In the three biotransformations, an 11β-hydroxylation was also produced, in low yield, indicating that a 7-oxo-group also directs hydroxylation at C-11.

Humic substances - compounds of still unknown structure: applications in agriculture, industry, environment, and biomedicine

Humic substances as part of humus-soil organic matter - are compounds arising from the physical, chemical and microbiological transformation (humification) of biomolecules. They are important because they constitute the most ubiquitous source of non-living organic material that nature knows. Approximately 80% of the total carbon in terrestrial media and 60% of the carbon dissolved in aquatic media are made up of humic substances. Humic substances have important roles in soil fertility, and are considered to have primal relevance for the stabilization of soil aggregates. They can be divided into three components according to their solubility: humic acids, fulvic acids and humin. Humic acids are the most explored group of humic substances. Beyond their relevance for life these substances have industrial applications in the development of absorbents to be used at the sources of metal-poisoning. Being natural substances, their purification process is cheaper than the synthesis of any other sorbent and, moreover, due to their high operability, they absorb more than the absorbents used to date, such as active charcoals or clays. The specific properties of humic acid products enable their application in industry, agriculture, environmental and biomedicine.

Biotransformation of two stemodane diterpenes by Mucor plumbeus

The microbiological transformation of 13α,17-dihydroxy-stemodane ( 2 ) by the fungus Mucor plumbeus afforded 13α,17,19-trihydroxy-stemodane ( 3 ), 3β,13α,17-trihydroxy-stemodane ( 5 ), 3-oxo-13α,17-dihydroxy-stemodane ( 7 ), 7α,13α,17,19-tetrahydroxy-stemodane ( 8 ), 3β,11α,13α,17-tetrahydroxy-stemodane ( 10 ), 3β,7α,13α,17-tetrahydroxy-stemodane ( 12 ), 3β,8β,13α,17-tetrahydroxy-stemodane ( 14 ), 2α,13α,17-trihydroxy-stemodane ( 16 ), 2α,13α,17,19-tetrahydroxy-stemodane ( 17 ), 2α,3β,13α,17-tetrahydroxy-stemodane ( 20 ) and 3β,11β,13α,17-tetrahydroxy-stemodane ( 22 ), whilst the incubation of 13α,14-dihydroxy-stemodane ( 25 ) gave 3β,13α,14-trihydroxy-stemodane ( 28 ), 2α,13α,14-trihydroxy-stemodane ( 29 ) and 13α,14,19-trihydroxy-stemodane ( 30 ). Preference for hydroxylations of ring A at C-2(α), C-3(β) and C-19 were observed in both incubations. An interesting rearrangement of 13α,14α-dihydroxy-stemodanes to 14-oxo derivatives with an unusual carbon framework has been observed under acetylation conditions. We have named this skeleton prestemodane, which, as a hydrocarbon ion, had been postulated as a biogenetic precursor of stemodane.

Biocenosis of BAC Fs used for groundwater treatment

The studies on the biocenosis of biologically active carbon filters (BAC F) used in treatment of Miocene water revealed the presence of protozoa of the group of flagellates and ciliates ( Glaucoma sp., Opercularia sp.), saprophytic bacteria, phase I and II nitrifying bacteria, Fe(II) and Mn(II) oxidizing bacteria of the family Siderocapsaceae, Leptothrix ochracea and Pedomicrobium sp., as well as microscopic fungi. The stratification of biofilter colonisation by these microorganisms was found to be similar to that occurring in biofilters applied in sewage treatment. A hypothetical model of microbiological transformations in BAC Fs, brought about by various physiological groups of microorganisms, is presented. It is shown that ozone pre-treatment of water dosed to the biofilter reduces the number of saprophytic bacteria and moulds in its upper layer, as well as Fe(II) oxidizing bacteria of the family Siderocapsaceae across the full section of the biofilter; it does not, however, influence the abundance of nitrifying phase I and II autotrophic bacteria and Mn(II) oxidizing bacteria of the family Siderocapsaceae. The abundance of microorganisms in the biofilter outflow is increased in comparison with that in untreated water; they do not, however, create a health hazard for human beings.

The microbiological transformation of the diterpenes dehydroabietanol and teideadiol by Mucor plumbeus

The microbiological transformation of dehydroabietanol (18-hydroxy-dehydroabietane) by Mucor plumbeus led to 2α,18-dihydroxy-abieta-8,11,13,15-tetraene, 2α,15-dihydroxy-dehydroabietanol, 2α-hydroxy-15-methoxy-dehydroabietanol, 7β-hydroxy-2-oxo-dehydroabietanol, 15-hydroxy-2-oxo-dehydroabietanol and 15,16-dihydroxy-2-oxo-dehydroabietanol, whilst that of teideadiol (1α,18-dihydroxy-dehydroabietane) gave 2α-hydroxy-teideadiol, 7α-hydroxy-teideadiol and 7β-hydroxy-teideadiol. Thus, 2α- and 7β-hydroxylation occur in both biotransformations and the 15-hydroxylation is inhibited in the biotransformation of teideadiol by the presence of a 1α-alcohol.

Microbiological Transformation of Cortexolone into Hydrocortisone

AbstractFor Abstract see ChemInform Abstract in Full Text.

Biotransformation of the diterpenes epicandicandiol and candicandiol by Mucor plumbeus.

The microbiological transformation of the diterpene epicandicandiol (1) with Mucor plumbeus gave foliol (3), sideritriol (5), and 7beta,16alpha,17,18-tetrahydroxy-ent-kaurane (7), while the incubation of candicandiol (2) gave 7alpha,9beta,18-trihydroxy-ent-kaur-16-ene (10), canditriol (11), and 7alpha,16alpha,17,18-tetrahydroxy-ent-kaurane (12). Thus, the main difference observed in both feedings, resulting from the spatial change in the orientation of the 7-hydroxyl, from axial in the substrate 1 to equatorial in 2, was the formation of a 3alpha- and a 9beta-hydroxylated derivative, respectively.

Natural sesquiterpenoids.

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. The literature from January to December 2002 is reviewed, and 388 references are cited.

Microbiological transformations. Part 51: The first example of a dynamic kinetic resolution process applied to a microbiological Baeyer–Villiger oxidation

The dynamic resolution of racemic 2-benzyloxymethylcyclopentanone 1 upon microbiologically mediated Baeyer–Villiger oxidation allowed the corresponding ( R)-lactone 2 to be prepared in 85% yield and 96% ee.

Microbiological transformation of L-tyrosine to 3,4-dihydroxyphenyl L-alanine (L-dopa) by a mutant strain of Aspergillus oryzae UV-7.

The present study deals with the microbiological transformation of L-tyrosine to 3,4-dihydroxyphenyl L-alanine by a mutant strain of Aspergillus oryzae UV-7. Sixteen different mutant strains of Aspergillus oryzae (GCB-6) were isolated through UV-irradiation. These mutant strains were screened for the production of mold mycelia by submerged fermentation in 250-ml Erlenmeyer flasks. Of all the mutant strains examined, UV-7 gave maximum production of L-dopa (1.28 mg/ml). The reaction was carried out using mold mycelium as a source of enzyme tyrosinase in shake flasks. The maximum production of L-dopa was obtained when glucose (25 mg/ml) was used as the carbon source and NH(4)Cl (3 mg/ml) was used as the nitrogen source. The optimum pH for mycelium development was 5.0; L-dopa production was maximum at pH 3.5 of the reaction mixture. The reaction by mold mycelium (75 mg/ml) was carried out under acidic conditions. Optimum temp, time, and L-tyrosine concentration were 55 degrees C, 60 min, and 3.0 mg/ml, respectively.

Natural sesquiterpenoids.

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. The literature from January to December 2001 is reviewed, and 404 references are cited.

Microbiological transformations 50: selection of epoxide hydrolases for enzymatic resolution of 2-, 3- or 4-pyridyloxirane

A study aimed to select efficient epoxide hydrolases (EHs) allowing to achieve the enzymatic resolution of 2-, 3- and 4-pyridyloxirane ( 1– 3) has been achieved, using 2-pyridyloxirane 1 as test substrate. Five thus selected EH-sources that showed interesting enantioselectivity were looked at in more detail for the conversion of 1– 3.

Microbiological transformations: 49. Asymmetric biocatalysed Baeyer–Villiger oxidation: improvement using a recombinant Escherichia coli whole cell biocatalyst in the presence of an adsorbent resin

The biocatalyst used in this work was whole cells of Escherichia coli TOP10 [pQR239] into which had been cloned the cyclohexanone mono-oxygenase from Acinetobacter calcoaceticus NCIMB 9871. Here we describe how, using whole resting cells of this recombinant strain, the biotransformation of bicyclo[3.2.0]hept-2-en-6-one ( 1) to its corresponding regioisomeric lactones (−)-(1 S,5 R)-2-oxabicyclo[3.3.0]oct-6-en-3-one ( 2) and (−)-(1 R,5 S)-3-oxabicyclo[3.3.0]oct-6-en-2-one ( 3) could be improved from levels of 1 g l −1 (9.3 mM) to 20 g l −1 (185 mM). The rate and yield of the biotransformation were improved by (i) increasing the cell concentration, (ii) using a specially designed vessel with high aeration rates, and (iii) adding an adsorbent resin directly to the biotransformation medium. We tested a series of resins and selected Amberlite XAD-4 and Optipore L-493 for further studies. In the presence of 100 g l −1 Optipore L-493 resin, 20 g l −1 bicycloheptanone ( 1) was successfully converted to a mixture of the two expected lactones at an overall yield of 83% (70% preparative yield after purification). Both these products were obtained in nearly enantiopure form (e.e.>98%).

Microbiological transformations. Part 48: Enantioselective biohydrolysis of 2-, 3- and 4-pyridyloxirane at high substrate concentration using the Agrobacterium radiobacter AD1 epoxide hydrolase and its Tyr215Phe mutant

The epoxide hydrolase (EH) from Agrobacterium radiobacter AD1 wild type (ArWT) and its Tyr215Phe mutant were compared for the biocatalyzed hydrolytic kinetic resolution (BHKR) of 2-, 3- and 4-pyridyloxirane. The regioselectivity of the oxirane ring opening as well as the substrate concentration limit and the inhibitory effect of the diol were determined. A gram scale preparation of enantiopure 2-pyridyloxirane (ee>98%) at a concentration as high as 127 mM (15.5 g/L) could be achieved with each of these two enzymes.