Mixed sugars to a multipurpose chemical: perspectives of 2,3-butanediol fermentability in complex lignocellulose hydrolysates.

2,3-Butanediol (2,3-BDO) is recognized for its industrial competitiveness and is predominantly produced in its enantiomerically pure form via microbial fermentation. The economical production of 2,3-BDO relies on the effective use of complex lignocellulosic materials and the advancement of inhibitor-resistant microbial strains. The robust expression of 2,3-BDO dehydrogenase in bacteria enhances volumetric productivity in inhibitor-rich lignocellulose hydrolysate. For instance, isolation of an inhibitor-resistant Klebsiella pneumoniae from palm oil effluent facilitated the synthesis of 75 g L⁻¹ of 2,3-BDO through separate hydrolysis and fermentation process. Conversely, the electrochemical detoxification of sugarcane bagasse hydrolysate increased the production of 2,3-BDO to 114.3 g L⁻¹ in Enterobacter aerogenes. Furthermore, deletion of glucose transporter (ptsG) in 2,3-BDO-producing bacteria mitigated carbon catabolite repression (CCR). Adaptive evolution of Paenibacillus polymyxa in non-detoxified wheat straw hydrolysate enhanced 2,3-BDO productivity to 0.72 g L⁻¹ h⁻¹. However, the rational engineering of yeast is complex, encompassing the heterologous expressions of xylose metabolism, 2,3-BDO dehydrogenase, and the deletion of the Crabtree effect. Nevertheless, partial disruption of the Crabtree effect in polyploid Saccharomyces cerevisiae resulted in increased production of 2,3-BDO (132 g L⁻¹) during the fed-batch fermentation of cassava hydrolysate. This review paper discusses the benefits and drawbacks of 2,3-BDO metabolism in both bacteria and yeast. The paper seeks to clarify the differences in 2,3-BDO production between detoxified and non-detoxified lignocellulosic hydrolysates. Further, the study illustrates the importance of generating 2,3-BDO from untreated lignocellulose via the development of microbial consortia. Economic factors that facilitate the commercialization of 2,3-BDO fermentation have been discussed in detail.