Screening for $α$-and $β$-galactosidases in Lactobacillus reuteri compared to different strains of bifidobacteria.

Six strains of L. reuteri and 9 bifidobacteria strains were screened for the activity of α-and β-galactosidases. Enzymatic activities were measured by determining the rate of hydrolysis of ρ-nitrophenyl-α-D- galactopyranoside and onitrophenyl-ß-D-galactopyranoside, respectively. Findings show that α-galactosidase activity in L. reuteri (0.067-0.603 GaI U/ml) was higher than that produced by bifidobacteria (0.013-0.396 GaI U/ml). α-Galactosidase activity of L. reuteri strains DSM20016 and MM2-3 were higher in comparison with the other bifidobacteria. DSM20016 had the highest αgalactosidase activity (0.603 GaI U/ml) among L. reuteri strains. β-Galactosidase activities for L. reuteri and bifidobacteria were in the range of 3.1×10^-4 -9.36 and 0.062-17.59 Gal U/ml, respectively. L reuteri MF14C showed the highest ß-galactosidase activity (17.59 GaI U/ml). L. reuteri strains MF14C and DSM20016 (12.87 GaI U/ml) showed higher β-galactosidase activity than bifidobacteria. Since L. reuteri is considered as Generally Regarded As Safe (GRAS), this could support the use of this bacteria in food industry.