Formation of a chiral acetoinic compound from diacetyl by Escherichia coli expressing meso-2,3-butanediol dehydrogenase.

L-Acetoin (L-AC) was produced from diacetyl (DA) by Escherichia coli JM109/pBUD119 containing the meso-2,3-butanediol dehydrogenase (D-AC forming) gene. However, when the strain was cultured in the presence of isopropyl-beta-D-thiogalacto-pyranoside, the enzyme formed catalysed not only D-AC but also L-AC. L-AC was further reduced to L-2,3-butanediol (BD). The yield of L-AC or L-BD from DA (3 gl-1) was about 70% (w/w).