Biological production of 2,3-butanediol.

2,3-Butanediol (2,3-BDL), which is very important for a variety of chemical feedstocks and liquid fuels, can be derived from the bioconversion of natural resources. One of its well known applications is the formation of methyl ethyl ketone, by dehydration, which can be used as a liquid fuel additive. This article briefly reviews the basic properties of 2,3-BDL and the metabolic pathway for the microbial formation of 2,3-BDL. Both the biological production of 2,3-BDL and the variety of strains being used are introduced. Genetically improved strains for BDL production which follow either the original mechanisms or new mechanisms are also described. Studies on fermentation conditions are briefly reviewed. On-line analysis, modeling, and control of BDL fermentation are discussed. In addition, downstream recovery of 2,3-BDL and the integrated process (being important issues of BDL production) are also introduced.