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Lactic acid fermentation is a metabolic process by which glucose or other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate, which is lactic acid in solution.
Anaerobic respiration is used by microorganisms, either bacteria or archaea, in which neither oxygen (aerobic respiration) nor pyruvate derivatives (fermentation) is the final electron acceptor. Rather, an inorganic acceptor such as sulfate ( SO 2− 4 ), nitrate ( NO − 3 ), or sulfur (S) is used. [ 16 ]
Generally, lactic acid fermentation occurs only when aerobic cells are lacking oxygen. However, some aerobic mammalian cells will preferentially use lactic acid fermentation over aerobic respiration. This phenomenon is called the Warburg effect and is found primarily in cancer cells. [9]
In aerobic respiration, oxygen is required. Using oxygen increases ATP production from 4 ATP molecules to about 30 ATP molecules. In anaerobic respiration, oxygen is not required. When oxygen is absent, the generation of ATP continues through fermentation. There are two types of fermentation: alcohol fermentation and lactic acid fermentation.
Despite the bactericidal effects of ethanol, acidifying effects of fermentation, and low oxygen conditions of industrial alcohol production, bacteria that undergo lactic acid fermentation can contaminate such facilities because lactic acid has a low pKa of 3.86 to avoid decoupling the pH membrane gradient that supports regulated transport. [7]
d -Glucose + 2 [NAD] + + 2 [ADP] + 2 [P] i 2 × Pyruvate 2 × + 2 [NADH] + 2 H + + 2 [ATP] + 2 H 2 O Glycolysis pathway overview The use of symbols in this equation makes it appear unbalanced with respect to oxygen atoms, hydrogen atoms, and charges. Atom balance is maintained by the two phosphate (P i) groups: Each exists in the form of a hydrogen phosphate anion, dissociating to contribute ...
Anaerobic cellular respiration and fermentation generate ATP in very different ways, and the terms should not be treated as synonyms. Cellular respiration (both aerobic and anaerobic) uses highly reduced chemical compounds such as NADH and FADH 2 (for example produced during glycolysis and the citric acid cycle) to establish an electrochemical gradient (often a proton gradient) across a membrane.
While fermentation produces adenosine triphosphate (ATP) only in low yield compared to the citric acid cycle and oxidative phosphorylation of aerobic respiration, it allows proliferating cells to convert nutrients such as glucose and glutamine more efficiently into biomass by avoiding unnecessary catabolic oxidation of such nutrients into ...