Expression and characterization of a novel highly glucose-tolerant [3-glucosidase from a soil metagenome  

作　　者：Jian Lu Liqin Du Yutuo Wei Yuanyuan Hu Ribo Huang 

机构地区：[1]State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, GuangxiUniversity, Nanning 530005, China [2]eNationalEngineering Research Center for Non-Food Biorefinery, Guangxi Academy of Sciences, Nanning 530004, China

出　　处：《Acta Biochimica et Biophysica Sinica》2013年第8期664-673,共10页生物化学与生物物理学报（英文版）

摘　　要：A β-glucosidase gene unbgllA was isolated by the function- based screening of a metagenomic library and the enzyme protein was expressed in Escherichia col, purified, and bio- chemically characterized. The enzyme UnbgllA had a Km value of 2.09 - 0.31 mM, and a Vma value of 183.90 ___ 9.61 μmol min-t mg- under the optimal reaction condi- tions, which were pH 6.0 at 50℃. UnbgllA can be activated by a variety of monosaccharides, disaccharides, and NaCI, and exhibits a high level of stability at high concentration of NaCl. Two prominent features for this enzyme are： （i） high glucose tolerance. It can be tolerant to glucose as high as 2000 mM, with Ki = 1500 mM; （ii） high NaCl tolerance. Its activity is not affected by 600 mM NaCI. The enzyme showed transglucosylation activities resulting in the forma- tion of cellotriose from cellobiose. These properties of UnbgllA should have important practical implication in its potential applications for better industrial production of glucose or bioethanol started from lignocellulosic biomass.A β-glucosidase gene unbgllA was isolated by the function- based screening of a metagenomic library and the enzyme protein was expressed in Escherichia col, purified, and bio- chemically characterized. The enzyme UnbgllA had a Km value of 2.09 - 0.31 mM, and a Vma value of 183.90 ___ 9.61 μmol min-t mg- under the optimal reaction condi- tions, which were pH 6.0 at 50℃. UnbgllA can be activated by a variety of monosaccharides, disaccharides, and NaCI, and exhibits a high level of stability at high concentration of NaCl. Two prominent features for this enzyme are： （i） high glucose tolerance. It can be tolerant to glucose as high as 2000 mM, with Ki = 1500 mM; （ii） high NaCl tolerance. Its activity is not affected by 600 mM NaCI. The enzyme showed transglucosylation activities resulting in the forma- tion of cellotriose from cellobiose. These properties of UnbgllA should have important practical implication in its potential applications for better industrial production of glucose or bioethanol started from lignocellulosic biomass.

关 键 词：Β-GLUCOSIDASE glucose tolerance METAGENOME 

分 类 号：TQ925.9[轻工技术与工程—发酵工程] Q933[生物学—微生物学]