title: Construction of a highly thermostable 1,3-1,4-β-glucanase by combinational mutagenesis and its potential application in the brewing industry.
abstract: OBJECTIVE
  To improve the thermostability and catalytic property of a mesophilic 1,3-1,4-β-glucanase by combinational mutagenesis and to test its effect in congress mashing.
  
  
  RESULTS
  A mutant β-glucanase (rE-BglTO) constructed by combinational mutagenesis showed a 25 °C increase in optimal temperature (to 70 °C) a 19.5 °C rise in T50value and a 15.6 °C increase in melting temperature compared to wild-type enzyme. Its half-life values at 60 and 70 °C were 152 and 99 min, which were 370 and 800 % higher than those of wild-type enzyme. Besides, its specific activity and kcatvalue were 42,734 U mg-1and 189 s-1while its stability under acidic conditions was also improved. In flask fermentation, the catalytic activity of rE-BglTO reached 2381 U ml-1, which was 63 % higher than that of wild-type enzyme. The addition of rE-BglTO in congress mashing decreased the filtration time and viscosity by 21.3 and 9.6 %, respectively.
  
  
  CONCLUSIONS
  The mutant β-glucanase showed high catalytic activity and thermostability which indicated that rE-BglTO is a good candidate for application in the brewing industry.
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.|Lab of Brewing Science and Technology, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.|International Center for Brewing and Distilling, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: Chengtuo
authors.initials: C
authors.lastname: Niu
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.|Lab of Brewing Science and Technology, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
authors.forename: Linjiang
authors.initials: L
authors.lastname: Zhu
authors.affiliation: International Center for Brewing and Distilling, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: Annie
authors.initials: A
authors.lastname: Hill
authors.affiliation: International Center for Brewing and Distilling, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: R
authors.initials: R
authors.lastname: Alex Speers
authors.affiliation: Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China. liqi@jiangnan.edu.cn.|Lab of Brewing Science and Technology, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China. liqi@jiangnan.edu.cn.
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
mesh_terms: D002384:Catalysis; D004795:Enzyme Stability; D005285:Fermentation / Q000502:physiology; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods*; D016296:Mutagenesis / Q000502:physiology
chemical_list: D006026:Glycoside Hydrolases
keywords: 1,3-1,4-β-Glucanase; Catalytic property; Combinational mutagenesis; Congress mashing; Thermostability