Abstract:As an extension of multi-enzyme immobilization strategy, enzyme-cell co-immobilization has become a new hot topic in enzyme engineering research because of its ability to enhance the catalytic performance of the system by hierarchically encapsulating different biomolecules of immobilized enzymes and cells. In order to use this new technology to enhance the synthesis of butyric acid, zinc zeolitic imidazolate framework-8@cellulase-Clostridium tyrobutyricum(ZIF-8@cellulase-Ct) co-immobilization system was prepared by constructing ZIF-8 separated with cellulase and Ct based on biomimetic mineralization method. The system was characterized by SEM, FT-IR and XRD techniques and analyzed by enzymatic and fermentation experiments, which showed that the system had better simultaneous saccharification and fermentation performance. 56.02% of corn cobs were hydrolyzed within at 40 ℃ and pH 4.5, and the glucose conversion rate was about 85.61%. Placed under different pH and oxygen concentrations, cells with ZIF-8@cellulase coating were found to have higher and more stable specific growth rate, cell viability and lower relative reactive oxygen levels, and the final concentration of ZIF-8-SSF butyric acid yield reached 6.74 g/L in 32 h, which was 12.52% higher than that of non-immobilized cells.
