An integration strategy of semi-continuous batch fermentation and foam separation: In situ concentration and recovery...

The traditional recycling process, characterized by multiple steps, high energy consumption and low efficiency, results in low product yield, significant enzyme activity loss, and high production costs. Therefore, it is crucial to develop a streamlined, gentle and efficient enzyme recycling technology. In this work, an integrated strategy of semi-continuous batch fermentation and foam separation was developed to in situ concentration and recovery of recombinant β-glucosidase from fermentation broth. After optimizing the recombinant β-glucosidase production process in the fermenter, to shorten the fermentation cycle, the third batch of semi-continuous fed-batch fermentation (harvested at 96 h intervals) for the production of recombinant β-glucosidase was adopted, resulting in an enzymatic activity of 3.52 ± 0.02 U/mL and a productivity of 36.67 ± 0.21 U/L·h. Integration the third fermentation batch with foam separation, an enrichment factor of 2.43 ± 0.03, protein yield of 70.94 ± 0.87%, and enzyme activity recovery of 94.56 ± 0.73% were achieved under optimal conditions. The recycled recombinant β-glucosidase enhanced saccharification efficiency by 2.5-fold when co-hydrolyzing sodium carboxymethyl cellulose with cellulose. Moreover, its saccharification efficiency toward cellobiose was comparable to that of the commercial enzyme. The fermenter system of this method simultaneously achieves in situ concentration and recovery of recombinant β-glucosidase. It effectively reduces the steps required for recovery of β-glucosidase while maintaining high enzyme activity, demonstrating significant potential for industrial-scale enzyme recovery.