title: Immobilization of recombinant thermostable beta-galactosidase from Bacillus stearothermophilus for lactose hydrolysis in milk.
abstract: A recombinant thermostable beta-galactosidase from Bacillus stearothermophilus was immobilized onto chitosan using Tris(hydroxymethyl)phosphine (THP) and glutaraldehyde, and a packed bed reactor was utilized to hydrolyze lactose in milk. The thermostability and enzyme activity of THP-immobilized beta-galactosidase during storage was superior to that of free and glutaraldehyde-immobilized enzymes. The THP-immobilized beta-galactosidase showed greater relative activity in the presence of Ca(2+) than the free enzyme and was stable during the storage at 4 degrees C for 6 wk, whereas the free enzyme lost 31% of the initial activity under the same storage conditions. More than 80% of lactose hydrolysis in milk was achieved after 2 h of operation in the reactor. Therefore, THP-immobilized recombinant thermostable beta-galactosidase from Bacillus stearothermophilus has the potential for application in the production of lactose-hydrolyzed milk.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China. weichen@jiangnan.edu.cn
authors.forename: W
authors.initials: W
authors.lastname: Chen
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Xia
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: F
authors.initials: F
authors.lastname: Tian
authors.forename: H P
authors.initials: HP
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000818:Animals; D005511:Food Handling; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007477:Ions / Q000378:metabolism; D007785:Lactose / Q000378:metabolism*; D008670:Metals / Q000378:metabolism; D008892:Milk / Q000737:chemistry*; D011994:Recombinant Proteins / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D007477:Ions; D008670:Metals; D011994:Recombinant Proteins; D001616:beta-Galactosidase; D007785:Lactose