关键词: 土壤宏基因组；漆酶；基因克隆；酶学性质

Abstract:

Laccase widely exists in soil and has potential industrial value in degradation of organic pesticide residues and lignin. In this study, a laccase gene, lac13H9, with total length of 1 389 bp was obtained from the soil macro genome. It encoded 462 amino acids polypeptide with a calculated molecular mass of 50 kDa and contained a signal peptide composed with 17 amino acid residues. The deduced amino acid sequence was a new protein through aligning with available protein sequences held in the NCBI. The recombinant lac13H9 heterologously expressed in Escherichia coli Transseta (DE3) and purified by the affinity chromatography on a Ni-NTA column. The maximal activity of laccase was observed at 40℃, the optimum pH was 6.0, and it had good thermal stability. About 60% enzyme activity was remained under 50℃ for 90 min. At the same time, low concentration of Fe2+ could promote laccase enzyme activity, while high concentration could inhibit enzyme activity. Fine enzymatic property of Lac13H9 has laid foundation for its application.