Improvement of (R,R)-2,3-butanediol production from corn stover hydrolysate by cell recycling continuous fermentation

Abstract

To achieve industrial (R,R)-2,3-butanediol ((R,R)-2,3-BDL) production from various lignocellulosic biomass, it is essential to develop an efficient fermentation process to overcome the challenge of carbon catabolite repression (CCR). The present study comprehensively investigated the effects of different glucose/xylose mixtures and fermentation strategies on (R,R)-2,3-BDL production using a nonpathogenic strain of Paenibacillus polymyxa. In both batch and fed-batch mode, we observed slow sugar utilization and a lower productivity. By employing cell-recycling continuous fermentation system for (R,R)-2,3-BDL production from mixed sugar, the volumetric productivity was significantly increased, by an average of 2-fold higher compared to alternative fermentation modes. Moreover, the (R,R)-2,3-BDL titer, volumetric productivity and yield achieved 18.80g/l, 1.13g/l/h and 0.313g/g when corn stover hydrolysates (CSH)was used as substrate. The results suggested that the reported fermentation system could efficiently eliminate CCR to improve (R,R)-2,3-BDL productivity. Thus, it had great potential for the industrial-scale (R,R)-2,3-BDL production from lignocellulosic hydrolysates.