The metabolic function of 2,3-butanediol is not known.
Comparison with mixed acid fermentation 
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
- M.Madigan & J. Martinko, 11th edition, (2006) Brock's Biology of Microorganisms, NJ, Pearson Prentice Hall, (p. 351-355)