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Acetogenesis is a process through which acetyl-CoA [1] or acetic acid is produced by anaerobic bacteria through the reduction of CO 2 via the Wood–Ljungdahl pathway.Other microbial processes that produce acetic acid (like certain types of fermentation or the oxidative breakdown of carbohydrates or ethanol by acetic acid bacteria) are not considered acetogenesis.
After the fermentation process, the AAB oxidizes the ethanol into acetic acid. The main difference between mother of vinegar and mother of kombucha is the acetic acid tolerance. Vinegar has a higher acetic acid concentration than kombucha, therefore the species in mother of vinegar needs to tolerate higher levels of acetic acid. [10]
Acetic acid bacteria (AAB) are a group of Gram-negative bacteria which oxidize sugars or ethanol and produce acetic acid during fermentation. [1] The acetic acid bacteria consist of 10 genera in the family Acetobacteraceae. [1] Several species of acetic acid bacteria are used in industry for production of certain foods and chemicals. [1]
Fermentation is a type of redox metabolism carried out in the absence of oxygen. [1] [2] During fermentation, organic molecules (e.g., glucose) are catabolized and donate electrons to other organic molecules. In the process, ATP and organic end products (e.g., lactate) are formed. Because oxygen is not required, it is an alternative to aerobic ...
Grapes being trodden to extract the juice and made into wine in storage jars. Tomb of Nakht, 18th dynasty, Thebes, Ancient Egypt. Sourdough starter. In food processing, fermentation is the conversion of carbohydrates to alcohol or organic acids using microorganisms—yeasts or bacteria—without an oxidizing agent being used in the reaction.
Industrial fermentation is the intentional use of fermentation in manufacturing processes. In addition to the mass production of fermented foods and drinks, industrial fermentation has widespread applications in chemical industry. Commodity chemicals, such as acetic acid, citric acid, and ethanol are made by fermentation. [1]
Acetic acid bacteria (AAB) incompletely oxidize sugars and alcohols, usually glucose and ethanol, to acetic acid, in a process called AAB oxidative fermentation (AOF). After glycolysis , the produced pyruvate is broken down to acetaldehyde by pyruvate decarboxylase , which in turn is oxidized to acetic acid by acetaldehyde dehydrogenase .
The process may be likened to how yeast ferments sugars to produce ethanol for wine, beer, or fuel, but the organisms that carry out the ABE fermentation are strictly anaerobic (obligate anaerobes). The ABE fermentation produces solvents in a ratio of 3 parts acetone, 6 parts butanol to 1 part ethanol.