Production of β-galactosidase by bifidobacteria as influenced by various culture conditions

beta-Galactosidase production by Biflidobacterium longum CCRC 15708, Bifidobacterium longum B6 and Bificlobacterium infantis CCRC 14633 was first examined with B. longum CCRC 15708 showing the highest production of beta-galactosidase and the highest specific activity. Further study with B. longum CCRC 15708 revealed that the highest level of beta-galactosidase was produced with lactose and yeast extract as carbon and nitrogen sources, respectively. Optimal enzyme production occurred at an initial pH of 6.5 and at 37 degrees C. Under these optimum culture conditions, a maximum beta-galactosidase activity of 18.6 U/ml could be obtained after 16 It of fermentation in a medium contain 4% lactose, 3.5% yeast extract, 0.3% K2HPO4, 0-1% KH2PO4, 0.05% MgSO4 center dot 7H(2)O and 0.03% L-cysteine. The highest transgalactosylation activity was also detected in this culture after 14-16 h of fermentation. (c) 2005 Elsevier B.V. All rights reserved.