Enhanced biobutanol production from starch waste via orange peel doping

Abstract

Acetone-butanol-ethanol fermentation is a promising bioprocess to produce biochemicals/bioenergy for sustainable development. However, high production cost, especially that associated with feedstocks, hinders its economic competitiveness with fossil-based processes. To reduce the feedstock cost and chemical footprints, orange peel waste rather than commercial chemicals such as yeast extract was used as a cofactor additive to enhance butanol production from source-separated rice waste instead of conventional feedstocks. Results showed that Clostridium sp. strain BOH3 produced 17.7 g/L butanol and 27.6 g/L acetone-butanol-ethanol solvents from 80 g/L multiple-source rice waste when supplemented with orange peel at an optimal dosage of 4 g/L. Compared with rice waste as the sole substrate, doping orange peel with rice waste improved solvent production and productivity by 72.2–101.7% and 242.2–295.5%, respectively. Meanwhile, orange peel accelerated the phase shift of acetone-butanol-ethanol fermentation from acidogenesis to solventogenesis by upregulating amylase- and butanol-dehydrogenase- encoding genes, thereby shortening the fermentation period. Finally, doping orange peel with starch waste reduced the feedstock cost by 69.6% and 97.7%, compared to the scenarios using food waste with yeast extract and glucose with commercial additives, respectively. Therefore, orange peel doping is an effective strategy for sustainable food waste management, and refined source separation policies are accordingly recommended.