Abstract:Based on the bioinformatics and genomics analysis, a glycoside hydrolase(GH) family 26 gene, Auman26A, which encodes β-mannanase mature peptide was cloned from Aspergillus usamii E001 by RT-PCR. Then, it was successfully expressed in Pichia pastoris GS115. The recombinant enzyme(reAuMan26A) activity of the fermentation supernatant towards locust bean gum was 281.9 U/mL. The specific activity of the purified enzyme was 2281.7 U/mg. The optimal temperature of reAuMan26A was 40 ℃. After incubating at 80 ℃ and 90 ℃ for 60 min, the residual activities were 60% and 33%, respectively. The half-life (t1/290) of reAuMan26A at 90 ℃ was 10 min. The optimal pH of reAuMan26A was 5.5, and it was stable over a range of pH 5.0~7.0. Its activity was not significantly affected by metal ions and EDTA, but inhibited by Fe2+ and Fe3+. Its most favorable substrate was locust bean gum, followed by konjac flour and guar gum. The Km and Vmax of reAuMan26A towards locust bean gum were 15.25 mg/mL and 7 841.9 U/mg, respectively. The superior properties of reAuMan26A, especially the excellent thermostability, make it have the broad application prospects in food, paper making and textile industry.
