Integrated fermentative production and downstream processing of 2,3-butanediol from sugarcane bagasse-derived xylose by mutant strain of Enterobacter ludwigii

Abstract

In this study, a mutant strain of Enterobacter ludwigii developed in our previous work, was evaluated to utilize pure xylose as the sole carbon and energy source for 2,3-butanediol (BDO) production. Later, this strain was also investigated on detoxified and nondetoxified xylose-rich hydrolysate obtained from hydrothermally pretreated sugarcane bagasse (SCB) for BDO production. Supplementing the fermentation medium with 0.2% w/v yeast extract improved cell growth (31%), BDO titer (43%), and yield (41%) against the synthetic medium devoid of any complex nitrogen source. The fed-batch culture with cyclic control of pH resulted in a BDO production of 71.1 g/L from pure xylose with overall yield and productivity of 0.40 g/g and 0.94 g/L·h, respectively. While BDO titer, yield, and productivity of 63.5 g/L, 0.36 g/g, and 0.84 g/L·h, were acheived with detoxified hydrolysate, respectively. In contrast, 32.7 g/L BDO was produced from nondetoxified hydrolysate with a conversion yield of 0.33 g/g and a productivity of 0.43 g/L·h. BDO accumulated on pure xylose and detoxified SCB hydrolysate was separated by aqueous two-phase system (ATPS) method using (NH4)2SO4 as salting-out agent and isopropanol as an extractant, resulting in the BDO recovery of more than 85%. The results achieved in the current work exemplify a step toward industrial BDO production from cost-effective hemicellulosic hydrolysates by E. ludwigii.