Acetoin and 2,3-butanediol production via non-pathogenic Paenibacillus polymyxa integrated with bio-based solvent pretreatment

2,3-Butanediol (2,3-BDO) is a promising platform chemical that can be derived from biomass and utilized for various industrial applications, including the production of sustainable aviation fuels. However, economically feasible and sustainable 2,3-BDO production from biomass is still challenging due to the recalcitrance of biomass. Moreover, most of the microorganisms utilized for 2,3-BDO fermentation are pathogens. Herein, this study presents a strategy using 2,3-BDO as a pretreatment solvent, followed by its regeneration via fermentation with a non-pathogenic bacterium, Paenibacillus polymyxa (P. polymyxa). This study elucidated the effects of 2,3-BDO pretreatment on the structural properties of lignin, fermentable sugar conversion, and 2,3-BDO productivity from switchgrass. The 2,3-BDO pretreatment significantly removed hemicellulose (up to 90% xylan) and 56.8% of lignin from switchgrass at 150 °C. The pretreated biomass resulted in 11.6 g/L of 2,3-BDO with a BDO yield of 0.486 g BDO/g sugar consumed at 48 h of microbial fermentation. The recovered lignin from 2,3-BDO pretreatment exhibited 4.5% β–O–4 linkage preservation at 150 °C. Additionally, 2,3-BDO pretreatment recovered up to 40.9% of xylooligosaccharide (XOS) from the liquid hydrolysates, which can be utilized for high-value products such as prebiotics. The utilization of 2,3-BDO as a biomass processing solvent is an attempt to promote plant cell wall fractionation, preserve lignin structure, and improve solvent regeneration via microbial fermentation.