Substratelevel Phosphorylation

Substrate-level phosphorylation is most significant in anaerobes, and yields of ATP are low. Consequently production of biomass is low and the production of fermentation intermediates for downstream metabolism by other microbes is high. Oxidation of organic molecules (removal of and H+) allows incorporation of inorganic phosphate and formation of a phosphorylated intermediate. Examples of such intermediates include 1,3-bisphosphoglycerate and phosphoenolpyruvate, both in the Embden-Myerhof-Parnas pathway, plus acetyl phosphate, in anaerobes that form acetate (Fig. 9.2). Hydrolysis of the phosphoryl group of these intermediates releases enough energy to form ATP when they are coupled with ADP and P;. For example, see Fig. 9.3, in which acetate kinase catalyzes the transfer of a phosphoryl group from acetyl phosphate to ADP ^ ATP.

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Worm Farming

Worm Farming

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