Alkane degradation

Alternative mechanisms for alkane degradation have been proposed for several organisms ... 

As the data in Table XIV indicate, over platinum demethylation of a ring is slow compared to C—C bond rupture within a ring. On the other hand, it is well established [e.g., Kochloefl and Bazant (161) that if one uses a supported nickel catalyst which is known to favor stepwise alkane degradation, reaction with an alkylcycloalkane is largely confined to the alkyl group (s) which are degraded in a stepwise fashion and are finally removed entirely from the ring. 

TABLE 15.1 Enantioselectivity and Activity of the Hydroxylation of A-Benzylpyrrolidine to Ai-Benzyl-3-hydroxypyrrolidine with Several Alkane-Degrading Strains... 

Susceptibility to n-alkane degradation is an inverse function of chain length. Branched alkanes are less susceptible than straight-chain n-alkanes, and the most resilient saturated components are the pristine and phytane isoprenoids (Wang et al. 1998). 

Fig. 16.32 Alkane degradation under aerobic conditions, showing incorporation of oxygen from molecular oxygen into the aliphatic compound, producing a fatty acid. Fatty acids are oxidized further by p-oxidation [H] indicates reducing equivalents that are either required or formed in the reaction step. (Bouwer and Zender 1993)...

So, C. M., and L. Y. Young, Initial reactions in anaerobic alkane degradation by a sulfate reducer, strain AK-10 , Appl. Environ. Microbiol., 65, 5532-5540 (1999). 

One potential limitation of the ENA approach is that MTBE is mineralized by only a few specialized bacteria and mainly imder aerobic conditions. Co-metabolic biotransformation of MTBE by aerobic, alkane-degrading bacteria has also been reported. Although several studies have demonstrated anaerobic biodegradation, anaerobic MTBE degradation rates are very low compared to aerobic rates. 

Figure 10. Alkane degradation by sediment bacteria from (O) Eastern Bay and (9) Colgate Creek...

Azoulay et al. (1963) reported that the first step of alkane degradation takes place with the help of a dehydrogenase, i.e. that oxygen is not necessarily required. But, by now, this possibility is considered quite improbable. Moreover, a di-terminal oxidation of alkanes appears to exist (lizuka et al, 1966). In this case the hydrocarbon chain is oxidatively attacked on both sides, and dicarboxylic acids are formed. This is important because it could thus be shown that the degradation paths finally open into the TCA (as proved by the formation of succinic acid). 

Dot blot hybridization has been used to monitor the alkB gene in n-alkane-degrading bacterial isolates [126]. The gene was shown to be widely spread among short-chain alkane degraders. Dot blot hybridization is also suitable for monitoring microbial communities after a bioremediation process [127]. 

Kara A, Syutsubo K, Harayama S (2003) Alcanivorax which prevails in oil-contaminated seawater exhibits broad substrate specificity for alkane degradation. Environ Microbiol 5 746-753... 

Vomberg A, Klinner U (2000) Distribution of alkB genes within n-alkane-degrading bacteria. J Appl Microbiol 89 339-348... 

Wang W, Shao Z (2012) Genes involved in alkane degradation in the Alcantvorax hongdengensis strain A-11-3. Appl Microbiol Biotechnol 94 437 448... 

Scheme 3.10 Proposed metabolic pathways for alkane degradation by microorganisms, ADH (alcohol dehydrogenase) AldDH (aldehyde dehydrogenase) and BVMO (Baeyer-Villiger monooxygenase).

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