Abstract: Laccase from Bacillus licheniformis has the advantages of high catalytic efficiency, wide range of substrates, etc., thus it owns the broad application prospect in industrial and agricultural fields. However, the expression level of the enzyme in the foreign gene expression system is low, which greatly limits its application in the agricultural and industrial fields. His-tag or S-tag is the small peptide with low molecular weight and usually can not affect the characteristics of heterologous fusion protein, and they are beneficial to be applied in the purification and detection of heterologous proteins. In this study, fusion of His-tag and/or S-tag on the N-terminal of the laccase CotA from B. licheniformis was constructed into pET-22b vector, and the vector was transferred into Escherichia coli BL(DE3), then we found that the soluble expression level of laccase significantly increased in E. coli BL(DE3). Compared with the construction without no fusion of any tags on N-terminal, the expression level with His-tag was about 37 folds, 20 folds with S-tag, and 28 folds with both His-tag and S-tag, respectively.

Key words: laccase, His-tag, S-tag, high expression