Methane methanogenic

Hydrogen produced by some anaerobic bacteria can be utilized by autotrophic bacteria to reduce oxidized organic compounds and COz to form either acetic acid (acetogenic bacteria) or methane (methanogenic bacteria), as follows ... 

Methanogen (Section 2 5) An organism that produces methane... 

Methane has also been used in aerobic bioreactors that are part of a pump-and-treat operation, and toluene and phenol have also been used as co-substrates at the pilot scale (29). Anaerobic reactors have also been developed for treating trichloroethylene. Eor example, Wu and co-workers (30) have developed a successful upflow anaerobic methanogenic bioreactor that converts trichloroethylene and several other halogenated compounds to ethylene. 

Hackstein et al ° have suggested that there may be a phylogenetic basis for the occurrence of significant methane formation in the gut of animals. It was argued that this refiected the presence of a methanogen receptor in the gut of animals which support large populations of these bacteria, since the production of... 

The incubation of 3,5-dichloro-4-methoxybenzyl alcohol with methanogenic sludge produced the de-O-methylated compound that was transformed to 2,6-dichlorophenol, and abiotically dimerized to fciX3,5-dichloro-4-hydroxyphenyl)methane (Verhagen et al. 1998) (Figure 2.2e). 

Degradation of hex-l-ene has been observed in a methanogenic consortium (Schink 1985a) that converted the substrate into methane, and a plausible pathway involving hydration and oxidation was suggested. 

Acetate may also be converted into methane by a few methanogens belonging to the genus Meth-anosarcina. The methyl group is initially converted into methyltetrahydromethanopterin (corresponding to methyltetrahydrofolate in the acetate oxidations discussed above) before reduction to methane via methyl-coenzyme M the carbonyl group of acetate is oxidized via bound CO to CO2. 

In Hg-resistant bacteria that are resistant to organic forms of Hg such as phenylmercuric acetate and methylmercury chloride, lyases are involved in the fission of the C-Hg to form Hg + and benzene or methane, and the enzyme has been partly purified (Schottel 1978). The Hg + may then be reduced to nontoxic Hg°. The situation under anaerobic conditions for sulfate-reducing bacteria is complicated by the possibility of both methylation and demethylation in the same strain (Pak and Bartha 1998), plausibly by operation of the acetyl-CoA pathway (Choi et al. 1994 Ekstrom et al. 2003). Under anaerobic conditions, demethylation, though not methylation, has been reported for a methanogen (Pak and Bartha 1998). 

Oremland RS, JP Zehr (1986) Formation of methane and carbon dioxide from dimethylselenide in anoxic sediments and by a methanogenic bacterium. Appl Environ Microbiol 52 1031-1036. 

A methanogenic bacterium was isolated from oil reservoir brines by enrichment with trimethylamine. Methane production occurred only with trimethyl-amine compounds or methanol as substrates. Sodium ions, magnesium ions, and potassium ions were all required for growth. This organism appears to be a member of the genus Methanohalophilus based on substrate utilization and general growth characteristics [695]. 

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