Abstract: 【Aim】 Reticulitermes flaviceps is one of the representative wood-feeding termite in our country, which has efficient cellulolitic system. This study aims to clone and characterize cellulase gene from R. flaviceps, so as to provide the theoretical basis for exploring cellulose resource of termites. 【Methods】 A β-glycosidase gene was cloned from R. flaviceps by using reverse transcription polymerase chain reaction ( RT-PCR), degenerate PCR and rapid amplification of cDNA end (RACE) methods, and its sequence was analyzed by bioinformatics tools. The corresponding protein was prokaryoticly expressed in Escherichia coli and the cellulase activity was measured after purification. 【Results】 The full-length cDNA sequence of β-glucosidase gene GZRfbg1 (GenBank accession no.: KU886065) was cloned from R. flaviceps, with a length of 1 691 bp and an open reading frame of 1 488 bp, encoding 448 amino acid residues with the typical structure of glycosyl hydrolase family (GHF) 1 domain. The calculated protein molecular weight is 56.45 kD. Multiple alignment analysis revealed that the deduced amino acid sequence of GZRfBG1 shares 95% identity with the salivary gland βglucosidase of Reticulitermes flavipes. GZRfBG1 was heterologously expressed in E. coli Rosetta 2 (DE3). The purified tagged GZRfBG1 exhibited increased specific activity to salicine, carboxymethyl cellulose sodium (CMC), and cellobiose. And the cellulolytic activity was also shown in a CMC containing agarose plate, in which clear digestion haloes were formed. 【Conclusion】 These results suggested that the salivary gland β-glucosidase from sibling species R. flaviceps and R. flavipes are very conservative in sequence and hydrolysis characteristics. This study of β-glucosidase gene can enrich the theoretical basis for the development of termite cellulases and phylogenetic study.

Key words: Reticulitermes flaviceps, β-glucosidas, cDNA, heterelogous expression, salivary gland