Microbial transformation products from

Microbial Transformation Products from 1,8-Cineole. The culture broth of A. niger cultured in the presence of 1,8-cineole (16, 1.5 g/1) for 7 days was extracted with ether. Gas chromatographic (GC) analysis of the extract revealed the formation of five products from 16. After the isolation of each products by column chromatography, 2-en 7o-hydroxycineole (17), 3-en 7o-hydroxycineole (20), 3-exo-hydroxycineole (21), 2-oxocineole (19) and 3-oxocineole (22) were identified from the interpretation of physico-chemical data (Figures 10 and 11) (18). All compounds were isolated as racemates. 

Earlier biotransformation studies with vindoline were reported from the Eli Lilly Laboratories (166-168), and microbial transformation products included N-demethylvindoline (48), deacetylvindoline (49), and a structurally novel com-... 

Microbial Transformation Products Obtained from Substrates 81a-81d by Various Microorganisms... 

In degradation experiments of radiolabelled LAS in soil columns, Branner et al. [29] observed that microbial transformation products, believed to be SPC, were virtually not retained on the column at all. Conversely, the results from the waterworks Rhine study [23] show that the subsequent slow sand filtration leads to a nearly total elimination of the SPC homologues. The residues detected in the water after this step... 

In general, transformation products have less persistence in the environment than the parent compounds. However, some transformation products from a range of chemical classes including certain carbamates, triazines, organophosphates, and sulfonylureas have often shown more persistence than the parent forms (Fig. 3) [3]. Meanwhile, it was pointed out that these observations might be skewed because of biased reports of more persistent transformation products and limitations of experimental design such as decreased microbial activity in the test system [3]. Differences between persistence of transformation products and their parent compoimds exist for sure therefore, case-by-case study of each chemical seems necessary to investigate the potential impact of the transformation products. 

TABLE 28.1 Microbial Transformation Products and Yields Obtained from Lupan-Family PTs ... 

Shordy thereafter, the M-4365 complex of six factors (A —A and G —G ), produced by M. capillata (275,276), was reported. From the izenamicin complex of seven factors produced by a M.icromonospora species, three were new fermentation products (277). Many compounds isolated are identical juvenimicin A, M-4365 A2, and izenamicin A are the same as rosaramicin. Stmctures have been proven by chemical interconversions (261,277,278) and microbial transformations (279). 

Microbial transformations of ellipticine (15) and 9-methoxyellipticine (16) were reported by Chien and Rosazza (143, 144). Of 211 cultures screened for their abilities to transform 9-methoxyellipticine (16), several, including Botrytis alii (NRRL 2502), Cunninghamella echinulata (NRRL 1386), C. echinulata (NRRL 3655), and Penicillium brevi-compactum (ATCC 10418), achieved O-demethylation of 16 in good yield (Scheme 9). P. brevi-compactum was used to prepare 9-hydroxyellipticine (22) from the methoxylated precursor, and 150 mg of product was obtained from 400 mg of starting material (37% yield). The structure of the metabolite was confirmed by direct comparison with authentic 9-hydroxyellipticine (143). O-Demethylation is a common microbial metabolic transformation with 16 and many other alkaloids (143). Meunier et al. have also demonstrated that peroxidases catalyze the O-demethylation reaction with 9-methoxyellipticine (145). 

Microbial transformations of four heteroyohimbine stereoisomers [ajmalicine (81a) tetrahydroalstonine (81b), isoajmalicine (81c), and akumigine (81d)] yielded mixtures of 10- and 11-hydroxylation products (786) (Scheme 21). Microorganisms known for their abilities to metabolize indole alkaloids, steroids, and antibiotics were intitially screened, and seven cultures were further used for preparative-scale incubations with alkaloid substrate. The microorganisms used and yields (by HPLC) of metabolites obtained from 81a-81d are shown in Table HI. 

As for the elimination efficiency of NPEO during wastewater treatment, values from 81 to 99.5% were calculated. However, the removal of parent NPEOs led to the formation of transformation products that are much more resistant to microbial degradation and overall elimination of nonylphenolic compounds during sewage treatment is very low. Ahel et al. [20] estimated that approximately 60-65% of all nonylphenolic compounds introduced to WWTP are discharged into the environment 19% in the form of carboxylated... 

One of the most undesirable aspects of microbial transformations in nature is the formation of toxicants. A large number of organic compounds which are themselves innocuous can be, and often are, converted to products that may be harmful to humans, animals, plants, and microorganisms. By such means, the environment may create a pollutant where none was present before. The process of forming toxic products from innocuous precursors is known as activation [171-177]. 

A project at the University of Arizona (FEDRIP 1996) will study microbial dehalogenation of several compounds, including chloroform. A major part of the study will focus on the facultative anaerobic bacteria Shewanella putrefaciens sp., which is known to catalyze the transformation of carbon tetrachloride to chloroform and other as yet unidentified products. The organic substrates will also contain metals. It is hoped that the end-products from the biochemical treatment can be subjected to a photolytic finishing process that will completely mineralize any remaining halogenated compounds. 

Biological. o-Phthalic acid was tentatively identified as the major degradation product of di-.n-octyl phthalate produced by the bacterium Serratia marcescens (Mathur and Rouatt, 1975). When di-.n-octyl phthalate was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, no degradation was observed after 7 d. In a 21-d period, however, gradual adaptation did occur, resulting in 94 and 93% losses at concentrations of 5 and 10 mg/L, respectively (Tabak et ah, 1981). In the presence of suspended natural populations from unpolluted aquatic systems, the second-order microbial transformation rate constant determined in the laboratory was reported to be 3.7 + 0.6 x lO L/organism-h (Steen, 1991). 

In every case the information provided has been obtained by collating public domain sources of information, but unfortunately very often little data is available, particularly on commercial aspects, even for products that have proved to be big successes. Thus microbial biotransformations for steroid modification, particularly stereoselective hydroxylations, such as the use of Rhizopus arrhizus to convert progesterone into antiinflammatory and other dmgs via 11- -hydroxyprogestrone, have proved to be very successful. However, comparatively little useful information exists from public domain sources, despite (or perhaps because) a market of hundreds of millions /a exists for such microbially transformed steroids (cortisone, aldosterone, prednisolone and prednisone etc.) produced by microbial hydroxylation and dehydrogenation reactions coupled with complimentary chemical steps. 

Recently, an industrial process development for nootkatone production from valencene by microbial transformation (bacteria, fungi) was mentioned [199, 200]. Although no details were given, the author claimed the development of an in situ product-removal technique by which an extremely selective recovery of nootkatone from the reaction mixture and the excess precursor during the proceeding production was achieved and which was said to be essential for an economically viable bioprocess. 

Building blocks derived from microbial transformations are usually employed as the key units of fluorinated analogs of appropriate natural products or synthetic biologically active materials [42-45]. Among such useful compounds, trifluoromethylated carbohydrates constitute one of the most interesting fields for intensive study. Novel and efficient routes to access a variety of chiral... 

Figure 17.1 Sequence of events in the overall process of biotrans-formations (1) bacterial cell containing enzymes takes up organic chemical, /, (2) i binds to suitable enzyme, (3) enzyme / complex reacts, producing the transformation product(s) of /, and (4) the product(s) is(are) released from the enzyme. Several additional processes may influence the overall rate such as (5) transport of / from forms that are unavailable (e.g., sorbed) to the microorganisms, (6) production of new or additional enzyme capacity [e.g., due to turning on genes (induction), due to removing materials which prevent enzyme operation (activation), or due to acquisition of new genetic capabilities via mutation or plasmid transfer], and (7) growth of the total microbial population carrying out the biotransformation of /. ...

Limonene (92) is the most widely distributed terpene in nature after a-pinene [68]. The (+)-isomer is present in Citrus peel oils at a concentration of over 90% a low concentration of the (-)-isomer is found in oils from the Mentha species and conifers [26]. The first data on the microbial transformation of limonene date back to the sixties. A soil Pseudomonad was isolated by enrichment culture technique on limonene as the sole source of carbon [69]. This Pseudomonad was also capable of growing on a-pinene, / -pinene, 1-p-menthene and p-cymene. The optimal level of limonene for growth was 0.3-0.6% (v/v) although no toxicity was observed at 2% levels. Fermentation of limonene by this bacterium in a mineral-salts medium resulted in the formation of a large number of neutral and acidic products. Dihydrocarvone, carvone, carveol, 8-p-menthene-1,2-cw-diol, 8-p-menthen-1 -ol-2-one, 8-p-menthene-1,2-trans-diol and 1 -p-menthene-6,9-diol were among the neutral products isolated and identified. The acidic compounds isolated and identified were perillic acid, /Msopropenyl pimelic acid, 2-hydroxy-8-p-menthen-7-oic acid and... 

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