Probiotic Properties and Cellular Antioxidant Activity of Lactobacillus plantarum MA2 Isolated from Tibetan Kefir Grains

 In recent years, probiotic lactic acid bacteria have received increasing attention because of their long history of safe use and their potential therapeutic benefits for human health. Though abundant researches were conducted to prove the excellent antioxidant effects of LAB on the aspects such as reducing oxidative damage, increasing the free radical scavenging rate, improving the activities of SOD and GSHPx, the systematic elucidation of the antioxidative mechanism of LAB is still in need.

Based on the preliminary research which showed MA2 with promising antioxidant potentials. In this study further investigation was pursued to evaluate the MA2 antioxidative effect with the CAA method.

CAA assay was applied to test the antioxidant capacity.

The results indicated that  MA2 had high antioxidant potential. The cell-free extract of the logarithmic phase was the most active, Fermentation supernatant has antioxidant activities. We found that the relative mRNA levels of the eight antioxidant-related genes (including cat, Gpx, gshR1~4, nox, npx) in MA2 in the logarithmic phase were higher than those in the stationary phase. These values may be attributed to the fact that the bacterial growth reached the stationary phase,  MA2 exhibited a high antioxidant activity in the logarithmic phase. The CAA method was successively applied to evaluate the antioxidant capacity of  MA2.