Immobilization of recombinant thermostable β-galactosidase from Bacillus stearothermophilus for lactose hydrolysis in milk

Chen, W.; Chen, H.; Xia, Y.; Yang, J.; Zhao, J.; Tian, F.; Zhang, H.P.; Zhang, H.

doi:10.3168/jds.2008-1618

« Previous Next »Journal of Dairy Science
Volume 92, Issue 2 , Pages 491-498, February 2009

Immobilization of recombinant thermostable β-galactosidase from Bacillus stearothermophilus for lactose hydrolysis in milk

W. Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
- Corresponding author.
H. Chen
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
Y. Xia
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
J. Yang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
J. Zhao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
F. Tian
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
H.P. Zhang
- Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, Inner Mongolia Agricultural University, Huhhot, Inner Mongolia 010018, P. R. China
H. Zhang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China

Received 11 August 2008; accepted 22 October 2008.

Abstract

A recombinant thermostable β-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 β-galactosidase during storage was superior to that of free and glutaraldehyde-immobilized enzymes. The THP-immobilized β-galactosidase showed greater relative activity in the presence of Ca²⁺ than the free enzyme and was stable during the storage at 4°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 2h of operation in the reactor. Therefore, THP-immobilized recombinant thermostable β-galactosidase from Bacillus stearothermophilus has the potential for application in the production of lactose-hydrolyzed milk.