Metabolic engineering of MG1 for enhanced production of ()-acetoin.

BACKGROUND

Optically pure acetoin (AC) is an important platform chemical which has been widely used to synthesize novel optically active α-hydroxyketone derivatives and liquid crystal composites.

RESULTS

In this study, C and A encoding -2,3-butanediol dehydrogenase (-2,3-BDH) and glycerol dehydrogenase (GDH), respectively, in MG1 were knocked out to block the conversion from AC to 2,3-butanediol (2,3-BD). The resulting strain MG14 was found to produce a large amount of optically pure ()-AC with a little 2,3-BD, indicating that another enzyme responsible for 2,3-BD formation except -2,3-BDH and GDH existed in the strain MG1. Furthermore, SlaR protein, a transcriptional activator of AC cluster, was overexpressed using promoter in the strain MG14, leading to enhancement of the ()-AC yield by 29.91%. The recombinant strain with overexpression of SlaR, designated as MG15, was used to perform medium optimization for improving ()-AC production.

CONCLUSION

Under the optimized conditions, 39.91 ± 1.35 g/l ()-AC was produced by strain MG15 with the productivity of 1.11 g/l h and the conversion rate of 80.13%.