High Acetone-Butanol-Ethanol Production from Food Waste by Recombinant Clostridium saccharoperbutylacetonicum in Batch and Continuous Immobilized-Cell Fermentation

Sustainable and economical production of butanol via acetone-butanol-ethanol (ABE) fermentation faces several major challenges, including high feedstock cost, low butanol yield, and low butanol productivity. To address these challenges, low-cost food waste was used as feedstock for ABE production in batch and continuous immobilized-cell fermentation by a recombinant high-butanol production strain Clostridium saccharoperbutylacetonicum deltptabuk. Food waste was first liquefied and saccharified to obtain fermentable sugars. After that, food waste hydrolysates were fed into both batch and continuous immobilized-cell fermentation systems to produce ABE. In the batch fermentation, only 14.32 g/L ABE was produced using food waste hydrolysates medium. However, when food waste hydrolysate medium was fed into the continuous immobilized-cell fermentation, remarkable increases of ABE production, yield, and productivity were achieved. At the dilution rate of 0.1 h^–1, 19.65 g/L ABE was produced with an ABE yield of 0.43. At the dilution rate of 0.39 h^–1, the highest ABE productivity (4.56 g/L/h) was obtained, which was 23 times higher than that in the batch fermentation. This study for the first time demonstrated efficient conversion of food waste to butanol via continuous immobilized-cell fermentation to achieve high titer and productivity, which would potentially support the advanced utilization of organic waste materials for biofuel production.