LI Xiao, XIE Liang, YANG Yun-nan, GAO Yan-hua. Screening and Identification of a Lactic Acid Bacterium Strain with Antioxidant Activity from Yak Yogurt[J]. Science and Technology of Food Industry, 2020, 41(19): 121-126. DOI: 10.13386/j.issn1002-0306.2020.19.019
Citation: LI Xiao, XIE Liang, YANG Yun-nan, GAO Yan-hua. Screening and Identification of a Lactic Acid Bacterium Strain with Antioxidant Activity from Yak Yogurt[J]. Science and Technology of Food Industry, 2020, 41(19): 121-126. DOI: 10.13386/j.issn1002-0306.2020.19.019

Screening and Identification of a Lactic Acid Bacterium Strain with Antioxidant Activity from Yak Yogurt

  • The study was conducted to screen and identify lactic acid bacterium with antioxidant activities from yak yogurt. The number of total bacterium and lactic acid bacterium strain was enumerated by plate counting method. The lactic acid bacterium was isolated by M17 agar supplemented with 2.5% CaCO3.The isolated strain was molecularly identified by 16S rRNA gene cloning and sequencing,and acid producing test and biochemical reaction test was also conducted to determine the biological characteristics of the isolated strain. Total antioxidative activity,DPPH free radical scavenging ability and hydroxyl radical scavenging ability was analyzed to determine the in vitro antioxidant activities of the isolated strain. The results showed that the isolated gram-positive lactic acid bacterial strain X1 identified as an acid-producing bacterium,with the biochemical characteristics of Enterococcus faecium. Furthermore,16S rRNA gene sequencing result confirmed that the isolated strain X1 belongs to the genus Enterococcus faecium. In vitro anti-oxidative activity analysis showed that the total anti-oxidative ability and the DPPH free radical scavenging ability of the cultured supernatant was significantly greater compared with the bacterial lysates and the bacterial resuspension,respectively(P<0.05). However,the hydroxyl radical scavenging ability of the bacterial resuspension was significantly greater compared with the cultured supernatant and the lysates(P<0.05). In conclusion,in the current study, Enterococcus faecium X1 with antioxidant activities was isolated and identified successfully from yak yogurt,and the antioxidant substances mainly existed in the cultured supernatant of this strain. These results could provide references for developing yak yogurt derived lactic acid bacterium into a novel antioxidative probiotic feed additive,and would be valuable for reducing oxidative stress during animal production.
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