Methane fermentation hydrogen formation

Methane fermentation in natural ecosystems is usually described as a two-stage system in which nonmethanogenic bacteria ferment organic matter such as carbohydrate yielding such products as acetate, formate, hydrogen, and carbon dioxide. The methanogenic bacteria are restricted... 

Fermentation of simple sugars results in formation of simple organic compounds such as lactate, succinate, and ethanol. These compounds can be fermented further by other bacteria to acetate, carbon dioxide, methane, and hydrogen. For example, conversion of ethanol to hydrogen and acetate results in an unfavorable positive energy yield. 

FlGURt Pathwaj-s of gas formation due to fiber fermeritation in the intestines. Some of the hydrogen gas produced by the carbohydrate fermenters may be released unchanged from the host. Methane production i.s variable in humans. About one-third of adult humans are methane producers. Some of the Hj may be used by methanogens for CJ f production. 

Badziong W, Thauer RK, Zeikus JG (1978) Isolation and characterization of Desulfovibrio growing on hydrogen plus sulfate as the sole energy source. Arch Microbiol 116 41—49 Barker HA (1956) Biological formation of methane. In Bacterial fermentation. Wiley, New York... 

The fermentation is accompanied by the formation of molecular hydrogen H3, with the accumulation of which its rate declines. In connection with these, the fermentation most successful in the presence of hydrogen-throphic microorganisms, which use as donor of electrons for reduction of CO3 and formation of methane. 

Preparation. In the laboratory methane can be prepared by hydrolysis of aluminum carbide (Al Cj) or to a lesser extent beryllium carbide (Be C) or by decomposing sodium acetate with sodium hydroxide. Carbon reacts with pure hydrogen to yield methane at temperatures above 1100°C but the reaction becomes noticeable only above 1500°C. In addition, a catalyst must be used to prevent the formation of acetylene. Commercially methane is only obtained from natural gas (see Section 17.5) or from fermentation of cellulose or sewage sludges. 

Isolation ergocristine from ergot or fermentation broth, its hydrogenation and salt formation with methane sulphonic acid... 

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