Anaerobes origins

Since the Earth was originally anaerobic, anaerobic microorganisms evolved in the Earth evolution and life origin. Outline the evidence for and implications of an anaerobic origin of Ufe. 

Reductive reactions typically occur in anaerobic environments where there is an abundant supply of electron donors. Electron donors are typically of microbial origin, eg, porphyrins or cysteine, which sometimes leads to confusion regarding the nature, ie, chemical vs enzymatic, of the reductive reaction. By definition, all reductive reactions which are not enzymatically catalyzed are chemical. The most significant chemical reductive reaction is reductive dechlorination. 

Besides being slower, anaerobic treatment is more difficult to manage and can generate by-products that are more mobile or toxic than the original compound, for example, the daughter products of TCE, ie, dichloroethenes and vinyl chloride. It requires a longer acclimation period which means slower startup times in the field. The microbial processes are less well understood, and hence, ate less controlled than for aerobic systems. 

Investigation showed that the explosion was due to hydrogen formed by anaerobic bacteria. In the original tank the splashing of the inlet liquor aerated the water and prevented anaerobic conditions. This did not apply in the new tank [20J. 

It is less conunonly known that methane was one of the original atmospheric gases and is a normal product of the microbial decomposition of organic matter under anaerobic conditions. Bacteria involved in production of methane are unique in their metabolism and other properties. The balanced... 

Fermentation occurs naturally in various microorganisms such as bacteria, yeasts, fungi and in mammalian muscle. Yeasts were discovered to have connection with fermentation as observed by Louis Pasteur and originally defined as respiration without air. However, it does not have to always occur in anaerobic condition. For example, starch when fermented under... 

Benzene and toluene were anaerobically hydroxylated to phenol and 4-hydroxytoluene, and experiments with H2 0 showed that the oxygen atoms had originated from water (Vogel and Grbic-Galic 1986). 

This enzyme catalyzes the conversion of pyruvate to formate and acetyl CoA and is a key enzyme in the anaerobic degradation of carbohydrates in some Enterobacteriaceae. Using an enzyme selectively C-labeled with glycine, it was shown by EPR that the reaction involves production of a free radical at C-2 of glycine (Wagner et al. 1992). This was confirmed by destruction of the radical with O2, and determination of part of the structure of the small protein that contained an oxalyl residue originating from gly-734. 

Garssen, G.J., Vliegenthart, J.F.G. and Boldingh, J. (1972). The origin and structures of dimeric fetty acids from the anaerobic reaction between soya-bean lipoxygenase, linoleic acid and its hydroperoxide. Biochem. J. 130, 435-442. 

First Steps The Evolution of Prokaryotes General Considerations of the Origins of Anaerobes... 

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