title: An acidophilic beta-galactosidase from Bispora sp. MEY-1 with high lactose hydrolytic activity under simulated gastric conditions.
abstract: BgalA, a full-length gene (3,009 bp) that encodes a beta-galactosidase, was cloned from the meso-acidophilic fungus Bispora sp. MEY-1 and expressed in Pichia pastoris. The deduced amino acid sequence of BgalA shares highest identity (55.5%) with the beta-galactosidase from Aspergillus phoenicis, which belongs to the glycoside hydrolyase family 35. Purified recombinant BgalA is acidophilic, exhibiting maximum activity at pH 1.5, which is lower than that reported for other beta-galactosidases. The enzyme has high pH and thermal stability and is resistant to proteases and cations found in milk. The K(m) and V(max) of BgalA for 2-nitrophenyl-beta-D-galactopyranoside and lactose are 5.22 mM and 120.8 micromol/(min x mg), and 0.31 mM and 137.3 micromol/(min x mg), respectively. Under simulated gastric conditions, BgalA has greater stability ( approximately 100%) and hydrolysis ratio (>80%) toward milk lactose than the commercially available beta-galactosidase from Aspergillus oryzae (ATCC 20423). Thus, BgalA may be a better digestive supplement for alleviating symptoms associated with lactase deficiency.
authors.affiliation: Key Laboratory of Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Huiying
authors.initials: H
authors.lastname: Luo
authors.forename: Yingguo
authors.initials: Y
authors.lastname: Bai
authors.forename: Yaru
authors.initials: Y
authors.lastname: Wang
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Pengjun
authors.initials: P
authors.lastname: Shi
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Yunliu
authors.initials: Y
authors.lastname: Fan
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D004063:Digestion; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005744:Gastric Acid / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D007785:Lactose / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D013270:Stomach / Q000502:physiology*; D001616:beta-Galactosidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D001616:beta-Galactosidase; D007785:Lactose