Enhanced butanol production from dough and okara waste through co-fermentation

Biobutanol production from waste via fermentation emerges as a promising solution for a sustainable waste-energy nexus. However, maximizing the resource potential of waste-derived feedstock for fermentation remains a hindrance to biobutanol production in the industry. To address this issue, co-fermentation of food processing waste, dough and okara, by Clostridium sp. strain BOH3 was explored to enhance biobutanol production. Results indicated that strain BOH3 generated 15.9 ± 0.90 g/L of butanol and 25.4 ± 1.43 g/L of acetone-butanol-ethanol solvents from 80 g/L co-substrate containing 85 % dough and 15 % okara, which represented a remarkable enhancement of butanol and solvent production with a notable increase of 91.6 % and 108.2 %, respectively, compared to sole fermentation of 80 g/L dough waste. In contrast, the sole fermentation of okara produced negligible amounts of solvent with acid as the dominant product due to the unsuitable carbon-to-nitrogen ratio intrinsic to okara for fermentation. Meanwhile, co-fermentation accelerated the acidogenesis-to-solventogenesis phase transition by balancing the carbon-to-nitrogen ratios and elevating the activity of amylase and butanol dehydrogenase by 1.7 folds when compared with the sole fermentation of dough waste. Findings in this study provided an effective co-fermentation strategy as well as the associated mechanistic insights regarding enhanced biobutanol production from dough and okara waste, promisingly contributing to sustainable waste-to-energy management.