title: Heterologous expression of a gene encoding a thermostable beta-galactosidase from Alicyclobacillus acidocaldarius.
abstract: A genomic DNA library screen yielded the nucleotide sequence of a 12 kb fragment containing a gene (2067 bp) coding a thermostable beta-galactosidase from Alicyclobacillus acidocaldarius ATCC 27009. The beta-galactosidase gene was expressed in Pichia pastoris, and up to 90 mg recombinant beta-galactosidase/l accumulated in shake flask cultures. Using o-nitrophenyl-beta-D: -galactopyranoside as a substrate, the optimum pH and temperature of the purified recombinant beta-galactosidase were 5.8-6.0 and 70 degrees C, respectively. The enzyme retained 90% of its activity when heated at 70 degrees C for 30 min. Approximately 48% of lactose in milk was hydrolyzed following treatment with the recombinant enzyme over 60 min at 65 degrees C.
authors.affiliation: Microbial Engineering Department, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Tiezheng
authors.initials: T
authors.lastname: Yuan
authors.forename: Peilong
authors.initials: P
authors.lastname: Yang
authors.forename: Yaru
authors.initials: Y
authors.lastname: Wang
authors.forename: Kun
authors.initials: K
authors.lastname: Meng
authors.forename: Huiying
authors.initials: H
authors.lastname: Luo
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Ningfeng
authors.initials: N
authors.lastname: Wu
authors.forename: Yunliu
authors.initials: Y
authors.lastname: Fan
authors.forename: Bin
authors.initials: B
authors.lastname: Yao
mesh_terms: D003001:Cloning, Molecular; D004795:Enzyme Stability; D016937:Gram-Positive Endospore-Forming Rods / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D001616:beta-Galactosidase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D001616:beta-Galactosidase; D007785:Lactose