Characterization of antioxidant properties of lactic acid bacteria isolated from spontaneously fermented yak milk in the Tibetan Plateau

This study investigated the antioxidant properties of lactic acid bacteria (LAB) isolated from spontaneously fermented yak milk collected on the Tibetan Plateau. Nine different species of LAB strains with high 2,2-diphenyl-1picrylhydrazyl radical-scavenging activity were screened from 403 isolates, and most of the selected LAB strains exhibited higher antioxidant activity than the reference strains from low-altitude areas. Among the 9 screened strains, L. delbrueckii subsp. bulgaricus F17 showed the greatest probiotic potential due to its high free radical scavenging activity (scavenging 59% OH and 54% O2−) and high survival rate (58%) within a simulated gastrointestinal tract. After administering the strain to ageing mice induced by d-galactose, the glutathione peroxidase activity in mouse livers and sera and the superoxide dismutase activities in mouse sera and brains increased significantly, while malondialdehyde levels in mouse livers and sera decreased significantly. This unique isolate could be considered a potential antioxidant strain for functional food production.