Efficient whole-cell biocatalyst for 2,3-butanediol/acetoin production with NADH/NAD(+) regeneration system in engineered Serratia marcescens.

Serratia marcescens is reported to possess the potential for industrial 2,3-butanediol or acetoin production by fermentation. But 2,3-butanediol or acetoin are always co-produced and this may make purification process difficult. So biocatalytic technologies may be the appropriate production methods. In this study, we developed an auto-inducing expression system based on pET system and swr quorum sensing system by using S. marcescens. By using this system, S. marcescens could be engineered as whole-cell biocatalyst to obtain 2,3-butanediol or acetoin. In order to convert diacetyl to 2,3-butanediol, formate dehydrogenase (FDH) and 2,3-butanediol dehydrogenase were co-expressed to construct a NADH regeneration system. This whole-cell biocatalyst could efficiently produced 53.6 g/L 2,3-butanediol with a productivity of 3.35 g/Lh. Next, in order to convert 2,3-butanediol to acetoin, NADH oxidase and 2,3-butanediol dehydrogenase were co-expressed to construct a NAD+ regeneration system. This whole-cell biocatalyst could efficiently produced 59 g/L acetoin with a productivity of 2.95 g/Lh. This work indicated this auto-inducing system was a powerful tool to construct whole-cell biocatalyst in S. marcescens in 2,3-butanediol and acetoin production.