Effect of ultrasound on bioconversion of isoflavones and probiotic properties of parent organisms and subsequent passages of Lactobacillus

Abstract

This study evaluated the effects of ultrasound (60 W; 3 min) on growth, bioconversion of isoflavones, and probiotic properties of parent organisms and subsequent passages of Lactobacillus casei FTDC 2113. Ultrasound significantly enhanced (P < 0.05) the cell growth of the parent organisms in mannitol–soymilk fermented at 37 °C over 24 h. Such treatment also enhanced the intracellular and extracellular β-glucosidase activity, leading to increased bioconversion of isoflavones in mannitol–soymilk (P < 0.05). In addition, treated cells also exhibited better tolerance toward acidic conditions (pH 2 and pH 3) and intestinal bile salts compared to the control (P < 0.05). Ultrasound also promoted cell adhesion ability and antimicrobial activity (P < 0.05). All these positive effects were only prevalent in the parent cells without inheritance by first, second and third passage of cells. Our results suggest that ultrasound could enhance the bioactive and probiotic potentials of parent cells of L. casei FTDC 2113, and could be used in the production of probiotic foods with enhanced bioactivity.