Nutraceutical Augmentation of Soybean Products Using Microbial β-Glucosidases

ABSTRACT Soybean is a healthful legume in terms of the presence of bioactive isoflavones viz. genistein, daidzein, and glycetein apart from high protein and unsaturated fat content. Soy isoflavones have several biological activities such as anti-estrogenic, anti-oxidative, and anti-cancer properties. However, they are present in biologically inactive glycosidic forms in soybean and their biological effects are dependent on deglycosylation during soy-processing or in the human gut. In these directions, food-associated and gut microbes possessing β-glucosidases activities hold potential to enhance the nutraceutical potential of soybean products by increasing the bioavailability of isoflavones. This review focuses on β-glucosidases-active microbes, their strain and species-specific variations and its impact on isoflavone aglycone content of the soybean-based foods. Further, microbial sources for isolating the native and recombinant β-glucosidases and their varying biochemical properties, and substrate specificities are discussed. Finally, augmentation of bioactivities of soybean products by fermentation with β-glucosidases-active microbes or treatment with purified β-glucosidases is discussed.