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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]
Acetogenesis is one of the main reactions of this stage, in this, the intermediary metabolites produced are metabolized to acetate, hydrogen and carbonic gas by the three main groups of bacteria: homoacetogens; syntrophes; and; sulphoreductors. For the acetic acid production are considered three kind of bacteria: Clostridium aceticum;
The worldwide production of acetic anhydride is a major application, and uses approximately 25% to 30% of the global production of acetic acid. The main process involves dehydration of acetic acid to give ketene at 700–750 °C. Ketene is thereafter reacted with acetic acid to obtain the anhydride: [50] CH 3 CO 2 H → CH 2 =C=O + H 2 O
Acetogenesis does not replace glycolysis with a different pathway, but rather captures the CO 2 from glycolysis and uses it to produce acetic acid. Although three molecules of acetic acid can be produced in this way, production of three molecules of ethanol would require an additional reducing agent such as hydrogen gas. [1]
Fermentation of feedstocks, including sugarcane, maize, and sugar beets, produces ethanol that is added to gasoline. [15] In some species of fish, including goldfish and carp, it provides energy when oxygen is scarce (along with lactic acid fermentation). [16] Before fermentation, a glucose molecule breaks down into two pyruvate molecules .
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]
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) 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.