The processing-module assembly strategy for continuous bio-oxidation of furan chemicals by the integrated and coupled biotechnology

Furoic acid (FA), a highly valuable intermediate from furfural, is widely used in the resin, plastic, food, and pharmaceutical industries. Currently, FA synthesis involves the oxidation of furfural by O2, catalyzed by noble metals, but the high-cost and low selectivity limit its industrial-scale production. Gluconobacter oxydans mediated FA bio-production by whole-cell catalysis of furfural presents a promising approach with advantages of high selectivity, safety, and environmentally friendly nature, while the bio-toxicity of furan chemicals always hinders their commercial production. In view of a processing-module assembly strategy, we designed a novel and prospective biotechnology to integrate the whole-cell catalysis step, electrodialysis separation step and crystallization/purification step (CCS–EDS–CPS) to achieve continuous and efficient FA bio-production from bio-toxic furfural by whole-cell catalysis. We found a significant enhancement in bioconversion productivity (>10 g L−1 h−1, 98% yield) and cell-recycling by rapid electrodialysis separation of bio-oxidized FA coupled with continuous feeding of furfural in the CCS, which alleviated the bio-toxicity of furan chemicals. Meanwhile, the highly pure FA end-product was spontaneously crystallized and precipitated at room temperature by the enrichment effect of EDS. Thus, the integrated and coupled method presents an advanced technical strategy using the processing-module assembly of biotechnology, and chemical and electrochemical techniques for the bio-oxidation of alcohols into carboxyl acids.