PerR Knockout Confers Oxygen Tolerance and Enhances Butanol/Acetone Production Through Elevated Titer and Productivity in Solvent-Degenerated Clostridium beijerinckii

The industrial potential of Clostridium beijerinckii for acetone-butanol-ethanol (ABE) fermentation is constrained by oxygen sensitivity and suboptimal solvent productivity. Targeted disruption of PerR (Cbei_1336) in the solvent-deficient C. beijerinckii DS strain confers robust oxygen tolerance and enhances ABE fermentation performance. The engineered Cbei_1336 mutant exhibited unprecedented aerobic growth under atmospheric oxygen (21% O2), achieving a 3.79-0.09-fold increase in biomass accumulation and a 2.84-0.12-fold improvement in glucose utilization efficiency compared to the degenerative parental strain. Transcriptomics analysis revealed that PerR knockout simultaneously upregulated oxidative defense systems and activated ABE pathway-related genes. This genetic rewiring redirected carbon flux from acidogenesis to solventogenesis, yielding a 9.64-0.90-fold increase in total solvent titer (15.61-0.89 vs. 1.62-0.12 g/L) and a 2.71-0.04-fold rise in volumetric productivity (0.19-0.01 vs. 0.07-0.01 g/L/h). Our findings establish PerR as a master regulator of both oxygen resilience and metabolic reprogramming, providing a scalable engineering strategy for industrial aerobic ABE bioprocessing to achieve low-cost biobutanol production.