Efficient (3R)-Acetoin Production from meso-2,3-Butanediol Using a New Whole-Cell Biocatalyst with Co-Expression of meso-2,3-Butanediol Dehydrogenase, NADH Oxidase, and Vitreoscilla Hemoglobin

Abstract

Acetoin (AC) is a volatile platform compound with various potential industrial applications. AC contains two stereoisomeric forms: (3<i>S</i>)-AC and (3<i>R</i>)-AC. Optically pure AC is an important potential intermediate and widely used as a precursor to synthesize novel optically active materials. In this study, chiral (3<i>R</i>)-AC production from <i>meso</i>-2,3-butanediol (<i>meso</i>-2,3-BD) was obtained using recombinant <i>Escherichia coli</i> cells co-expressing <i>meso</i>-2,3-butanediol dehydrogenase (<i>meso</i>-2,3-BDH), NADH oxidase (NOX), and hemoglobin protein (VHB) from <i>Serratia</i> sp. T241, <i>Lactobacillus brevis</i>, and <i>Vitreoscilla</i>, respectively. The new biocatalyst of <i>E. coli</i>/pET-<i>mbdh</i>-<i>nox</i>-<i>vgb</i> was developed and the bioconversion conditions were optimized. Under the optimal conditions, 86.74 g/l of (3<i>R</i>)-AC with the productivity of 3.61 g/l/h and the stereoisomeric purity of 97.89% was achieved from 93.73 g/l <i>meso</i>-2,3-BD using the whole-cell biocatalyst. The yield and productivity were new records for (3<i>R</i>)-AC production. The results exhibit the industrial potential for (3<i>R</i>)-AC production via whole-cell biocatalysis.