Effects of ultrasound on growth, bioconversion of isoflavones and probiotic properties of parent and subsequent passages of Lactobacillus fermentum BT 8633 in biotin-supplemented soymilk

► Ultrasound enhanced growth and β-glucosidase activity of parent Lactobacillus acidophilus. ► Higher accumulation of isoflavone aglycones during fermentation in biotin-soymilk. ► Such traits were not exhibited by treated cells of subsequent passages. ► Ultrasound demoted certain probiotic properties of parent cells. ► These probiotic properties were improved in treated cells of subsequent passages. This study aimed to evaluate the effects of ultrasound on Lactobacillus fermentum BT 8633 in parent and subsequent passages based on their growth and isoflavone bioconversion activities in biotin-supplemented soymilk. The treated cells were also assessed for impact of ultrasound on probiotic properties. The growth of ultrasonicated parent cells increased (P