Determining ?-Galactosidase Activity of Commercially Available Probiotic Supplements

Abstract

Consumer interest in probiotics has dramatically increased in recent years due to improved knowledge of the significant benefits imparted on human health. A specific health issue in which probiotics have been found advantageous is lactose intolerance. Probiotics have demonstrated the ability to act on ingested lactose due to the presence of lactase. The objective of this study was to assess the β-galactosidase (β-gal) activity of commercially available probiotics supplements in the market. Ten supplements were used in this study. Two capsules of each supplement were allowed to activate in MRS broth for 10-12 h. Cultures were then inoculated into TPY broth with lactose (induced) or glucose (uninduced) then incubated at 37°C. After bacterial growth reached the mid log phase (optical density 0.7-0.9; 610 nm), the procedures as outlined by Miller were followed. Activity of β-gal was quantified using the o-nitrophenyl-β-D-galactoside (ONPG) assay. The activity of β-gal in the uninduced group ranged between 0 and 800 Miller unit, whereas there as the induced group ranged from 1 to 1,120 Miller units. When induced, supplement #5 exhibited the strongest enzyme activity at 1,120 Miller units and supplement #10 exhibited the lowest activity. Similarly, supplement #3 exhibited the highest (800 Miller unit) and supplements #1, #2 and #10 did not show any β-gal activity with glucose. These findings indicate that β-gal activity in the ten tested supplements varies. Our results suggest that not all of the commercially available probiotic supplements have the same health benefits.