Optimization of soluble expression of recombinant Paenibacillus spβ- glucosidase in Escherichia coli

Objective: β- glucosidase has great application value in food industry. However, a major problem withβ- glucosidase recombinant expression is inclusion body formation. Common methods to reduce inclusion body formation are not always effective, thus new strategy is needed.Methods: β- glucosidase encoding gene bgl was amplified by PCR from Paenibacillus sp genome, and then was constructed into p ET28 a. The resulting vector p ET- bgl was transformed into Escherichia coli BL21 ( DE3) to obtain recombinant strain BL- ETbgl, and the induction conditions were optimized.By replacing the replication origin of p ET- bgl, p ACYT- bgl was developed and transformed into BL21 ( DE3) to obtain strain BL- ATbgl.Results: The recombinant expression product of BL- ETbgl has β- glucosidase active. However, 40% of product was expressed as inclusion body. Conversely, most recombinant product of BL- ATbgl was soluble, and the maximum yield of recombinant β- glucosidase could reach to 2.31 × 106 U / L by conditions optimized.Conclusion: By combined with reducing plasmid copy number and optimizing induction conditions, the soluble expression level of Paenibacillus sp β- glucosidase was improved significantly.