title: Purification, gene cloning and characterization of an acidic β-1,4-glucanase from Phialophora sp. G5 with potential applications in the brewing and feed industries.
abstract: An extracellular β-1,4-glucanase (CelG5, ∼55.0 kDa) was isolated from the culture filtrate of Phialophora sp. G5, and its encoding gene was cloned. The deduced amino acid sequence of CelG5 was at most 73.6% and 44.0%, respectively, identical with a hypothetical protein from Sordaria macrospora and an experimentally verified GH 7 endo-β-1,4-glucanase of Neurospora tetrasperma FGSC 2508. Native CelG5 had pH and temperature optima of pH 4.5-5.0 and 55-60°C. The enzyme showed some properties superior than most fungal β-1,4-glucanases, such as high activity over a wide pH range (exhibiting >50% of the maximum activity at pH 2.0-7.0), excellent stability in extreme acidic to alkaline conditions (pH 2.0-9.0), and strong resistance against pepsin and trypsin (retaining 89% and 94% activity, respectively). Recombinant CelG5 produced in Pichia pastoris had a molecular mass and a pH optimum similar to native CelG5, but with maximal activity at 65°C. Application tests showed that native CelG5 was stable under simulated gastric conditions (retaining >70% activity), and had capacity to decrease the viscosity of barley-bean feed (8.9% by 200 U CelG5) and mash (6.1% by 50 U CelG5) and increase the filtration rate of mash (18.4% by 50 U CelG5). These properties make CelG5 a good candidate for utilization in the animal feed and brewing industries.
authors.affiliation: Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Beijing 100081, PR China.
authors.forename: Junqi
authors.initials: J
authors.lastname: Zhao
authors.forename: Pengjun
authors.initials: P
authors.lastname: Shi
authors.forename: Tiezheng
authors.initials: T
authors.lastname: Yuan
authors.forename: Huoqing
authors.initials: H
authors.lastname: Huang
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Li
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D000821:Animal Feed; D001483:Base Sequence; D002480:Cellulase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D003001:Cloning, Molecular; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology; D008969:Molecular Sequence Data; D010676:Phialophora / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D002480:Cellulase