Caproate production from the mixture of corn straw and food waste via chain elongation with reinforcement of biofilm

As a precursor, caproate is widely used in food and medicine for production of various valuable products. From an environmental point of view, caproate production by anaerobic fermentation is a sustainable way. The cost of caproate could be reduced if the wasted biomass is used as substrate. In this study, the caproate production from corn straw and food waste was investigated. Results showed that the sulfuric acid – enzyme method was the optimum approach for hydrolysis of corn straw, and the corresponding glucose concentration was 24.3 g/L. At the optimum condition, the 5-hydroxymethyl furfural (HMF) was found to be the main inhibitor of the hydrolysate, which exhibited inhibitory effect to ethanol and caproate fermentation. Further analysis showed that the inhibition threshold of HMF to Clostridium kluyveri was 1.2 g/L. The formation of biofilm in the fermentation system was found to be an effective way for improving the robustness of cells to inhibitors. The caproate production of 13.5 g/L was obtained when the ethanol and acetate derived from corn straw and food waste was used as substrates. This study cast an insight that it was a promising way for caproate production from the corn straw and food waste.