Evaluation of β-Galactosidase Activity of Commercial Probiotic Supplements Available in the Local Market in Greensboro, North Carolina

Abstract

The objective of this study was to evaluate the ?-galactosidase activity of commercial probiotic supplements available in the market. Fifteen different supplements (15) were included in the study. Two capsules of each supplement were transferred into 10 ml fresh, sterile MRS broth and incubated at 37 °C for 10-12 h to allow bacterial cells to recover from any environmental stressors. Aliquots from each supplement (100µl) were then inoculated into batches of 10ml TPY broth with lactose (induced) or glucose (un-induced) and incubated for 14 hr. at 37°C. After bacterial growth reached the mid log phase (optical density 0.7-0.9; 610 nm), the ?-gal activity was determined using o-nitrophenyl-?-D-galactoside (ONPG) as a substrate. The activity of ?-gal in the uninduced group ranged between 0 and 600 Miller units, whereas activity in the induced group ranged from 0 to 1300Miller units. These findings indicate that ?-gal activity in the tested supplements varies. This would mean that commercially available probiotic supplements exhibit different degrees of activity, and consumers should be aware of this variability when choosing probiotic supplements that purportedly confer health benefits.