Screening of lactic acid bacteria with high antioxidant capacity in Tibetan Plateau yak yogurt

The H₂O₂-resistant capacity of 881 strains which isolated from yak yoghurt in the Qinghai Tibet Plateau was introduced in this paper and 8 strains were screened out. It was also studied the scavenging abilities on DPPH radical,OH radical,O₂^- radical and total antioxidant capacity. The results showed that intact cells of lactic acid bactera scavenged the DPPH radical were more significantly than cell-free extracts while the opposite to clean up OH radical,O₂^- radical and total antioxidant capacity. According to the data,strains BX62,XS40 and XM5 had outstanding performance in the scavenging of free radicals. The intact cells of BX62 showed the highest ability to scavenge DPPH free radical(33.52%) at the concentration of 10~9CFU/m L. Besides its cellfree extracts also had the best scavenging ability on O₂^-radical(48.85%). While the cell-free extracts of XS40 showed the highest ability to scavenge OH radical(52.12%). In addition,3 strains also had higher T-AOC activity. 3 strains screened out in this paper were Lactobacillus parplantarum BX62,Lactobacillus plantarum XM5,and Pediococcus acidilactici XS40 by 16 S r RNA identification and phylogenetic analysis. In this study,3 strains of lactic acid bacteria screened out from yak yogurt in the Qinghai Tibet Plateru really had high antioxidant activity,which would have an application prospect as a natural antioxidant in the future.