Enhanced Chiral D-(-)-2,3-Butanediol Production by Engineered Corynebacterium glutamicum from Glucose and Xylose Mixtures

The platform chemical 2,3-butanediol has a wide range of applications, and especially can be used as an alternative for biofuel production. Noticeably, chiral pure D-(-)-2,3-butanediol with spatial configuration has unique applications i.e. antifreeze and chiral intermediates. Herein, the non-pathogenic Corynebacterium glutamicum (could not naturally produce 2,3-butanediol) was engineered to produce chiral D-(-)-2,3-butanediol from glucose, xylose and arabinose mixtures. Initially, with the purpose of D-(-)-2,3-butanediol production in C. glutamicum, its native butA gene (coding meso-2,3-butanediol dehydrogenase) was deleted, and an artificial gene cluster, encoding the 2,3-butanediol biosynthetic pathway from Bacillus subtilis was introduced. The resulted mutant could produce 20.78 g/L D-(-)-butanediol from 50 g/L glucose in flask experiment in minimum medium with a yield of 0.43 g/ g glucose, and 78 g/L D-(-)-butanediol within 50h in the 5-L fermentor. Subsequently, to synchronously assimilate glucose and xylose as substrate, the xyloseisomerase and xylulokinase coding genes xylA and xylB from Xanthomonas campestris were introduced into C. glutamicum. In shake-flask fermentations, 51 g/L D-(-)-2,3-butanediol with a yield of 0.35 g/ g mixed sugar was obtained by the optimum strain CGF32, which offered a novel strategy on engineering microbe as cell factory for the production of high-valued chemicals from renewable resource.

Keywords
Metabolic engineering; D-(-)-2,3-butanediol; Corynebacterium glutamicum; xylose.