Branched alkanes metabolism

Pirnik MP, RM Atlas, R Bartha (1974) Hydrocarbon metabolism by Brevibacterium erythrogenes normal and branched alkanes. J Bacterial 119 868-878. 

Singer, M.E. and Finnerty, W.R. Microbial metabolism of straight-chain and branched alkanes, in Petroleum Microbiology, Atlas, R.M., Ed. (New York Macmillan, 1984), pp. 1-59. 

Aliphatic EC>8-EC16 Fraction. Hydrocarbons in this fraction are oxidatively metabolized to fatty acids and alcohols, apparently mediated by cytochrome P-450 isozymes (see Miller et al. 1996 for review). Studies regarding the metabolism of hydrocarbons in this fraction in humans or animals provide suggestive evidence that metabolism may be slow. In a study of humans exposed to 100 ppm white spirit 6 hours/day for 5 days (white spirit is a mixture comprised predominately of C10-C12 linear and branched alkanes), only minor differences were observed in the GC-MS spectrum of hydrocarbons in biopsied fatty tissue, than in the spectrum of hydrocarbons in the test material (Pedersen et al. 

E. J. McKenna, Microbial metabolism of normal and branched alkanes, in Degradation of Synthetic Organic Molecules in the Biosphere, Natl. Acad. Sci, Washington D.C., 1972, p. 73. 

Marine bacteria and yeast may ameliorate the effects of the apparently inevitable oil spillages at sea . Hundreds of such organisms have been isolated from the Arctic that can metabolize diesel oils down to 10 °C and bacterial communities that can degrade n-chain and branched alkanes have been characterized ... 

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. 

Cometabohc cultiues in MTBE degrading reactors may have some positives. The cometabohc strains normally grow much faster than strains which utihse direct metabolism. Furthermore, the simple branched chain alkanes used as energy soiuce diuing cometabohsm reactions are normally present in MTBE plumes caused by gasoline leaks. The use of cometabohc strains can result in faster reactor startup. Knowledge of the apphcabihty and hm-itations of cometabohc strains in bioreactors is limited and needs further research. 

The toxicity of organic fluorine compounds depends on their biochemical stability and the toxicity of metabolites. The carbon-fluorine bond is highly resistant to biochemical degradation and, as a consequence, perfluoroearbons are physiologically inactive. However, if a fluorochemical is metabolized, the toxicity of the metabolized fluorocompound depends on the structure of the metabolites. Monofluorinated alkanoic acids are toxic when the j8-oxidation mechanism can produce monofluoroacetic acid [2]. Steric hindrance and branching of the alkane chain reduce toxicity (Table 10.1). 

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