Efficient 2,3-butanediol fermentation from biomass-derived sugars using Bacillus licheniformis DSM 8785

2,3-butanediol (BD) is a promising platform chemical with enormous industrial applications in food, fuel, chemical, pharmaceutical, and polymer. High final titer, use of biomass-derived sugars, and non-pathogenic microbial culture are critical factors for the sustainable BD production via biological routes. In our study, a non-pathogenic bacterium, Bacillus licheniformis DSM 8785, was evaluated for BD fermentation, and compared with Klebsiella oxytoca ATCC 8724; K. oxytoca are reported as the most robust BD producers, but not desirable for bulk chemical production due to its pathogenicity. The results showed that B. licheniformis utilized both glucose and xylose; decreased fermentation performance resulted in a mixed sugar medium. BD productivity in glucose, xylose and mixed sugar (glucose:xylose = 2:1) medium was 2.23, 1.58 and 0.91 gL^-1h^-1, respectively.  BD fermentation using sorghum stalks hydrolyzate with 4% (w/v) total sugar was as efficient as synthetic sugars; poor xylose consumption was observed using hydrolyzates with 8% sugar concentration.  A high BD titer (115 g/L) was obtained from fed-batch fermentation using glucose medium after four feedings, but the BD productivity gradually decreased as the fed-batch proceeded. As compared to K. oxytoca, the B. licheniformis culture had 2.2 and 2.5 times greater BD productivity using glucose and xylose medium, respectively, but was less efficient in biomass hydrolyzate with 8% sugars. This study determined that efficient BD production is possible using a non-pathogenic organism from single sugar medium; an appropriate biomass processing technology should be developed to obtain separate glucose and xylose streams from lignocellulosic biomass for better BD fermentation performance.