Oxidations microbial

Gestodene has been prepared in several ways (85). The route that provides the highest yield is shown in Eigure 8. Microbial oxidation of (55) with Penicillium raistrickii results in the 15-alcohol (56). Protection of the alcohol as the acetate (57) and protection of the ketone as a dienolether provides (58). In a one-pot procedure (58) is treated with lithium acetyUde and subjected to a hydrolytic work-up to provide gestodene (54) (86). 

Experimental procedures have been described in which the desired reactions have been carried out either by whole microbial cells or by enzymes (1—3). These involve carbohydrates (qv) (4,5) steroids (qv), sterols, and bile acids (6—11) nonsteroid cycHc compounds (12) ahcycHc and alkane hydroxylations (13—16) alkaloids (7,17,18) various pharmaceuticals (qv) (19—21), including antibiotics (19—24) and miscellaneous natural products (25—27). Reviews of the microbial oxidation of aUphatic and aromatic hydrocarbons (qv) (28), monoterpenes (29,30), pesticides (qv) (31,32), lignin (qv) (33,34), flavors and fragrances (35), and other organic molecules (8,12,36,37) have been pubflshed (see Enzyp applications, industrial Enzyt s in organic synthesis Elavors AND spices). 

In another process, diosgenin is degraded to 16-dehydropregnenolone by chemical methods. Conversion of 16-dehydropregnenolone to 11-deoxycortisol (125) can be accompHshed in 11 chemical steps. These steps result in hydroxylations at C21 and C17, oxidation at C3, and to double-bond isomeri2ation (175). Microbial oxidation of (125) also produces cortisol (29). 

The specificity of biocatalysts also extends to site specificity (regiospecificity). This means that if several functional groups of one type are present on the molecule, only one specific position will be affected. An example of this is the microbial oxidation of D-soibitol to L-soibose, a key step in the synthesis of vitamin C (Figure 2.4). 

Patel RN, CT Hou, AI Laskin, A Felix (1982) Microbial oxidation of hydrocarbons properties of a soluble monooxygenase from a facultative methane-utilizing organisms Methylobacterium sp. strain CRL-26. Appl Environ Microbiol 44 1130-1137. 

Bradley PM, FH Chapelle, DR Lovley (1998) Humic acids as electron acceptors for anaerobic microbial oxidation of vinyl chloride and dichloroethene. Appl Environ Microbiol 68 3102-3103. 

Carless HAJ, Oak OZ (1991) Total synthesis of (-)-laminitol (lD-4C-methyl-myo-inositol) via microbial oxidation of tolnene. Tetrahedron Lett 32 1671-1674. 

Ley SV, F Sternfield, S Taylor (1987) Microbial oxidation in synthesis a six step preparation of (+/-)-pinitol from benzene. Tetrahedron Lett 28 225-226. 

Dagley S, PA Johnson (1963) Microbial oxidation of kynurenic, xanthurenic and picolinic acids. Biochim Biophys Acta 78 577-587. 

FIGURE 10.51 Transformation of benzothiophene involving microbial oxidation and chemical reaction of the sulfoxide. (From Neilson, A.H. and Allard, A.-S., The Handbook of Environmental Chemistry, Vol. 3J, pp. 1-80, Springer, Heidelberg, 1998. With permission.)... 

Enantiomerically pure alkyl aryl sulfoxides have been obtained by the microbial oxidation of the corresponding sulfides (Holland 1988). Both Corynebacterium equi, and fungi... 

Pirnik MP (1977) Microbial oxidation of methyl branched alkanes. Crit Rev Microbiol 5 413-422. 

Lonza, for example, has commercialized processes for highly chemo- and regioselective microbial ring hydroxylation and side-chain oxidation of heteroaromatics (see Fig. 2.32 for examples) (Kiener, 1995, 1999). The pharmaceutical intermediate 5-methylpyrazine-2-carboxylic acid, for example, is manufactured by microbial oxidation of 2,5-dimethylpyrazine. Many conversions of the type shown in Fig. 2.32 would not be possible by conventional chemical means. 

Microbial oxidation of drug substrates occurs in a similar fashion to mammalian oxidative biotransformation. In contrast, microbial cultures rarely catalyze conjugations comparable to those in mammalian system (glucuronidation, sulfation and GSH conjugation). It is thus not surprising that microbial bioreactors are mainly used in the synthesis of oxidative metabolites. 

Losi M.E., Frankenberger W.T. Microbial oxidation and solubilization of precipitated elemental selenium in soil. J Environ Qual 1998 27 836-843. 

Kargi, F., and Robinson, J. M., Microbial Oxidation of Dibenzothiophene by the Thermophilic Organism Sulfolobus Acidocaldarius. Biotechnology and Bioengineering, 1984. 26 p. 687. 

The University of Osaka is the holder of two patents regarding the least studied biorefining processes, demetallization, and bioconversion. The metals are removed from the fossil fuel, under mild conditions (room temperature and atmospheric pressure) by the microbial oxidation action and a UV-photochemical reaction [166], The bioconversion refers to conversion of high molecular weight alkanes by the action of B. thermoleovorans B23 and B. thermoleovorans H41 strains to lower molecular weight molecules [167],... 

The catalyst efficiency of these hydroalumination varies from a turnover number (TON) of 20-91. It is possible that the catalyst is deactivated by the presence of oxygen and water. Examination of the 31P NMR spectrum of the catalyst indicates that the phosphine monoxide and dioxide are formed in the presence of nickel prior to the addition of the substrate. Rigorous exclusion of oxygen and water is necessary in all these reactions. The enantioselective nickel-catalyzed hydroalumination route to dihydronaphthalenols may prove to be particularly important. Only one other method has been reported for the enantioselective syntheses of these compounds microbial oxidation of dihydronaphthalene by Pseudomonas putida UV4 generates the dihydronaphthalenol in 60% yield and >95% ee.1... 

Upon burial in the sediments, organic matter is microbially oxidized in a sequence dictated by the Gibbs Free Energy yield of each reaction (Froelich et at., 1979). The oxidants are used in this sequence respiration of oxygen,... 

The following exemplifies how the total balance of a redox reaction is completed taking an electron donor and an electron acceptor (cf. the outline of the total redox reaction in Figure 2.3). Example 2.2 is, in this respect, used as an example of an (microbial) oxidation of an electron donor (organic matter) under anoxic conditions, i.e., with reduction of NO3 as electron acceptor (cf. Example 2.4). 

Injection of air the oxygen in the injected air will prevent sulfate-reducing conditions in the sewer. The DO concentration in the wastewater establishes an aerobic upper layer in the biofilm, and sulfide produced in the deeper part of the biofilm or the deposits that may diffuse into the water phase will be oxidized (cf. Figure 6.2). The oxidation of sulfide will mainly proceed as a chemical process, although microbial oxidation may also take place (Chen and Morris, 1972). Factors that affect the oxidation rate of sulfide include pH, temperature and presence of catalysts, e.g., heavy metals. 

Microbial nitrile hydratase, 76 400 Microbial oxidations, 76 401 Microbial pesticides, 78 525... 

See also Biotransformations Microbial oxidations Microbial reductions applications of, 76 396-399 biocatalyst selection in, 76 404-409 biocatalysts in, 76 409-414 for drug metabolite production, 76 398-399 further advances in, 76 414 in hydrolysis, 76 400-401 multiphase reactions in, 777 412-414 scale-up of, 76 414 systematic studies of, 76 398 technique overview for, 76 403-414 timing of substrate additions in, 76 411-412 uses for, 777 400-403 Microbial waxes, 26 203 Microbiocides, triorganotins as, 24 817 Microbiological culture media, agar in, 73 68... 

The rate of a reaction can also be an important factor in both the amount and longevity of a component in soil. A very common and interesting example is the microbial oxidation of ammonia first to nitrite and then to nitrate. 

Energy is given as AG° for each reaction. The microbial oxidation of ammonia to nitrite in soil is found to be slower than the oxidation of nitrite... 

A 2 1 (- )-90-LAH reagent was employed in the asymmetric synthesis of a cij-diol (91) by reduction of c/j-2-acetoxy-6-phenylcyclohexanone (99,100). Diol 91 is of interest as the tetrahydro derivative of a metabolite obtained from the microbial oxidation of biphenyl. Diol 91 was obtained in 46% e.e. as determined by NMR in the presence of a chiral shift reagent. It was shown to have the absolute stereochemistry (lS,2/ )-dihydroxy-3(S)-phenylcyclohexane by oxidation to ( + )-2-(S)-phenyladipic acid of known absolute stereochemistry. 

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