Butanediol fermentation

2,3-Butanediol fermentation is fermentation of glucose with 2,3-butanediol as one of the end products. The overall stoichiometry of the reaction is

Butanediol fermentation is typical for the facultative anaerobes Klebsiella and Enterobacter and is tested for using the Voges–Proskauer (VP) test.

The metabolic function of 2,3-butanediol is not known, although some have speculated that it was an evolutionary advantage for these microorganisms to produce a neutral product that's less inhibitory than other partial oxidation products and doesn't reduce the pH as much as mixed acids. .

2,3-butanediol fermentation produces smaller amounts of acid than mixed acid fermentation, and butanediol, ethanol, CO₂ and H₂ are the end products. While equal amounts of CO₂ and H₂ are created during mixed acid fermentation, butanediol fermentation produces more than twice the amount of CO₂ because the gases are not produced only by formate hydrogen lyase like they are in the mixed acid fermentation

2,3 Butanediol is produced at varying levels in aerated fermentations as long as the dissolved oxygen level is limiting (i.e., the culture is trying to consume more oxygen than is available). The degree of oxygen limitation dictates the ratios of 2,3-butanediol to by-products produced (2)

2. N. B. Jansen, M. C. Flickinger, G. T. Tsao (1984). "Production of 2,3-butanediol from D-xylose by Klebsiella oxytoca ATCC 8724." Biotechnol. Bioeng. 26 (4): 362-8.

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