Co-production of a whole cellulase system in Escherichia coli

Usually, glucose production from cellulose hydrolysis involves synergistic actions by exoglucanase, endoglucanase and β-glucosidase. To co-produce a whole cellulase system in Escherichia coli, a multi-promoter construct and a multi-cistronic construct harboring an exoglucanase (CbhA), an endoglucanase (CenA) and a β-glucosidase (BGL) were built herein. Synergistic effect of three enzymes was also investigated. The results showed synergism of CenA and BGL played a critical role in degrading filter paper to glucose. Compared with monocistronic constructs, multi-promoter and multi-cistronic constructs harboring three enzymes showed significantly higher glucose yield. The specific activity of multi-promoter construct was 22.5-fold and 6.9-fold higher than CbhA and CenA, respectively and that of multi-cistronic construct was 33.6-fold and 10.3-fold higher than CbhA and CenA, respectively. In conclusion, a whole cellulase system could be co-produced in E. coli for converting cellulose to glucose. Moreover, the strategy could be easily applied to other cellulolytic enzymes, as well as for other multi-enzymatic systems.

► A multi-promoter construct was built to co-express a whole cellulase system. ► A multi-cistronic construct was built to co-express a whole cellulase system. ► Synergistic effect of cellulases expressed in the work was investigated. ► Significantly higher glucose was produced with co-expression strategy.