Invited review: Properties of β-galactosidases derived from Lactobacillaceae species and their capacity for galacto-oligosaccharide production

0-galactosidase (enzymatic class 3.2.1.23) is one of the dairy industry's most important and widely used enzymes. The enzyme is part of a large family known to catalyze hydrolysis and transglycosylation reactions. Its hydrolytic activity is commonly used to decrease lactose content in dairy products, while its transgly-cosylase activity has recently been used to synthesize galacto-oligosaccharides (GOS). During the past couple of years, researchers have focused on studying 0-galactosidase isolated and purified from lactic acid bacteria. This review will focus on 0-galactosidase puri-fied and characterized from what used to be the Lac-tobacillus genera. Furthermore, particular emphasis is given to its kinetics, biochemical characteristics, GOS production, market, and utilization by Lactobacillla-ceae species.