Detoxification with resin promotes the shift from acidogenesis to solventogenesis and prevents acid crash during butanol fermentation from wheat straw

Wheat straw is the second most abundant agricultural biomass. Conversion from wheat straw to butanol, the second-generation biofuel, offers an economically feasible and ecologically viable strategy to minimize environmental pollution. However, by-products generated during wheat straw pretreatment severely inhibit the subsequent fermentation by microbial strains and need to be removed prior to fermentation. In this study, three detoxification methods were evaluated for their ability to improve butanol fermentation with Clostridium acetobutylicum CICC 8012 from wheat straw hydrolysate. Strong acid cation exchange resin 001 × 7 exhibited the best comprehensive performance, yielding 2.03 g/L of acetic acid, 0.59 g/L of butyric acid, 7.42 g/L of butanol, and 12.97 g/L of acetone–butanol–ethanol. These values were 77.72% lower, 85.32% lower, 518.33% higher, and 582.63% higher, respectively, than those in the un-detoxified group. Further investigation revealed that treatment with 001 × 7 alleviated the depletion of ATP and NADH to ensure adequate supply of energy and reducing power for the shift from acidogenesis to solventogenesis. Transcriptome analysis revealed that detoxification reinforced the acid reassimilation route and the direct formation route for butanol formation, resulting in significantly improved fermentation performance by reducing acetic acid and butyric acid metabolic flux and increasing butanol metabolic flux. This study demonstrates a novel approach for detoxification of wheat straw hydrolysate with the cost-saving resin 001 × 7 and reveals the mechanism underlying the improvement in butanol fermentation performance observed following 001 × 7 treatment. Graphical abstract