Alkanes microbial oxidation

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). 

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

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],... 

Subterminal alkane oxidation apparently occurs in some bacterial species (Markovetz, 1971). This type of oxidation is probably responsible for the formation of long-chain secondary alcohols and ketones. Pirnik (1977) and Perry (1984) have reviewed the microbial oxidation of branched and cyclic alkanes, respectively. Interestingly, none of the cyclohexane or cyclopentane compounds seems to be metabolized by pure cultures. Rather, non-specific oxidases present in many bacteria convert the cyclic alkanes into cyclic ketones, which are then oxidized by specific bacteria. 

Microbial oxidation of alkanes can take place at the terminal carbon, in which case an alcohol is the initial product, or at a subterminal position (often the -position) to give either the secondary alcohol or a ketone. In both cases further oxidation s can take place to give carboxylic acids, themselves liable to oxidation and shortening of the carbon chain by successive two-carbon units (Scheme 2). 

Assuming that the yield is 100% with respect to hydrocarbon and 50% with respect to glucose, the process with alkanes requires 2.6 times more oxygen for the production of the same quantity of cells. In the microbial oxidation of hydrocarbons, cases of limited oxygen supply have been reported (Klug and Markovetz, 1969 Yamada et al, 1968). 

Fatty acids derived from alkanes have received considerable attention as surfactants. Rehm and Reiff 1981 have published a detailed list of fatty acids resulting from the microbial oxidation of alkanes. The hydrophUic-lipophilic balance (HLB) of fatty acids is clearly related to the length of the hydrocarbon chain. For lowering surface and interfacial tensions, the most active saturated fatty acids are in the range of C-12 to C-14. In addition to straight-chain fatty adds, microorganisms produce... 

Bacterial utilization and degradation of hydrocarbons. The oxidation of higher hydrocarbons under aerobic conditions by Micrococcus, Pseudomonas, Mycobacterium, and Nocardia is an important environmental process by which petroleum wastes are eliminated from water and soil. The initial step in the microbial oxidation of alkanes is conversion of a terminal -CH3 group to a -CO2 group followed by p-oxidation,... 

The interdigital secretion of the red hartebeest, A. b. caama, consists of fewer compound classes. It contains a few alkanes and short-chain, branched alcohols, fatty acids, including a few of the higher fatty acids up to octadecanoic acid, an epoxide and the cyclic ethers, rans-(2 ,5.R)-furanoid linalool oxide 23, as-(2JR,5S)-furanoid linalool oxide 24 and ds-(2S,5i )-furanoid linalool oxide 25 (Fig. 5) in a ratio of 2.5 1 1.5 respectively [138]. From the point of view that many of the constituents of the interdigital secretion of this animal are probably of microbial origin, it is interesting that cis- and trans- furanoid linalool oxides have also been found in castoreum [77]. 

Figure 1. Intermediates in the aerobic microbial metabolism of n-alkanes by a terminal oxidation and subsequent p-oxidations.

In addition, the occurrence of n-alkan-2-ones (C23 to C29) at sampling locations A,B,E and G suggested terrigenous contributions to the coastal sediments due to the proposed formation by microbial P-oxidation of corresponding higher plant derived n-alkanes (Allen et al., 1971 Cranwell, 1981a Riley et al., 1991). 

Allen JE, Fomey FW, Markovetz AJ (1971) Microbial subterminal oxidation of alkanes and alk-l-enes. Lipids 6, 448-452. 

The data for yield, growth rate and productivity differ very greatly for microbial alkane oxidations. Since the growth parameters depend on the substrate and the organism, the data cannot be generalized. However, we get the impression that yield and productivity are low for short alkane chains and for cyclic chains. For medium and very long chains, typical yield values fluctuate between 70-90% (see Table 6). 

Reductions Microbial and mammalian nitroreductase reduces nitro compounds to amines. Chlorinated alkanes and alkenes are common contaminants in ground water and chlorinated aromatics, PCBs, organochlorine pesticides, are often detected in soils and sediments and it has been of interest to evaluate the potential for these compounds to be metabolized. A number of microorganisms are able to dechlorinate both halogenated aliphatic and aromatic compounds in a reduction reaction." It has been observed that the more highly chlorinated congeners are more reactive in these systems in contrast to the response in oxidative dechlorinations. 

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