High-level production and characterization of a novel β-1,3-1,4-glucanase from Aspergillus awamori and its potential application in the brewing industry

Publication date: Available online 25 January 2020Source: Process BiochemistryAuthor(s): Xueqiang Liu, Zhengqiang Jiang, Shuai Ma, Qiaojuan Yan, Zixian Chen, Haijie LiuABSTRACTA novel β-1,3-1,4-glucanase gene (AaBglu12A) from Aspergillus awamori was extracellularly expressed in Pichia pastoris. AaBglu12A showed amino acid identity of 96% with a glycoside hydrolase family 12 cellulase from A. kawachii and 48% with a β-1,3-1,4-glucanase from Magnaporthe oryzae. The highest β-1,3-1,4-glucanase activity of 159,500 ± 500 U/mL with protein concentration of 31.7 ± 0.3 g/L was achieved in a 5-L fermentor. AaBglu12A was purified until homogeneous with recovery yield of 92%. Its maximal activity was found at 55 °C and pH 5.0. The enzyme was stable up to 60 °C and within the pH range of 2.0-9.0. It also demonstrated strict substrate specificity towards oat- and barley-glucans as well as lichenan. The Km values for oat-, barley-glucans, and lichenan were 2.82, 3.51, and 2.53 mg/mL, respectively. The Vmax values for oat-, barley-glucans, and lichenan were 12,068, 10,790, and 7,236 μmol/(min·mg), respectively. AaBglu12A hydrolyzed oat- and barley-β-glucans to produce tetra- and tri-saccharides. However, lichenan was hydrolyzed to yield trisaccharides as the main end product. The addition of AaBglu12A to the mashing process substantially decreased filtration time by 34.5% and viscosity by 9.6%. Therefore, the high-level production of AaBglu12A might be a promisin...
Source: Process Biochemistry - Category: Biochemistry Source Type: research