β-Glucosidase activity and bioconversion of isoflavone glycosides to aglycones by potential probiotic bacteria

Abstract

The enzyme, β-glucosidase (β-Glu; EC 3.2.1.21), is a commercially important enzyme. First, β-Glu enzyme and specific activity were screened in total of 54 strains. In these strains, β-Glu-specific enzyme activity was assessed varying from 0.250 to 3.000 U/mg. Next, β-Glu enzyme belonging to the strains (Lactobacillus rhamnosus EA1 and Lactobacillus casei SC1) that exhibited high β-Glu-specific enzyme activity optimization were done. In these strains, optimum pH was 7.5, optimum temperature was 30°C, and optimum buffer was potassium phosphate. Then, the strains that displayed high β-Glu-specific enzyme activity were decided to hydrolyze the isoflavone glucosides using high-pressure liquid chromatography. Finally, following the partial purification of β-Glu enzyme, its molecular weight was detected to be approximately 78 K. Ultimately, in the present study, β-Glu enzyme acquired from L. casei SC1 strain became prominent because its activity was higher. It did not lose its activity under different environmental conditions and demonstrated high hydrolyzing the isoflavone.