Research Of Nitrite Reduction Ability And Antioxidant Activity Of Se-enriched Lactobacillus

As a biology carrier to transform inorganic selenium into organic selenium, LAB have been developed as selenium dietary supplements. It`s functional properties have partly been ascribed to the biological functions which were improved by Selenium. There is an increasing interesting in enhancing food safety and increasing health benefits as the increasing number of Se-selenium fermented foods. Researchers have demonstrated that inoculation of LAB is more effective in lowering nitrite concentration of fermented vegetable and enhancing anti-oxygenic ability of yoghurt. So far, little attention has been paid to the role of lactic acid bacteria in those phenomena. In this paper, a strain(Lactobacillus plantarum) was isolated and used to study the effect of Se on nitrite degradation capacity and antioxidant activity of LAB. The main research in this paper is listed as follows:1. There were 11 LAB were screened from homemade fermented pickles sample. A strain which has nitrite degradation ability was isolated and named L.P2. This strain is gram-positive bacterium. The cell of the strain is in the shape of short and arranged in pairs. 16 SrDNA result shows that the strain was Lactobacillus plantarum.2. Basic medium appended with different concentrations of Se were used to LAB culture. According to the selenium endurance and inorganic selenium transform ability of the strains, the addition of Se was determined. Results showed that 2.0mg/L was the optimal amount and the biomass increased by 35.88%. The transform amount is proportional to the addition of Se, but he conversions were Se4.0>Se6.0>Se2.0>Se8.0. The optimum adding amount was 0-2 mg/L. The reduction and tolerance capability of Se-enriched lactobacillus were investigate further. Our results suggest that the reduction in Se2.0 increased by 26.63% in 72 h, and the reduction in Se2.0 in 24 h was higher than Se0 in 72 h. By comprehensive analysis, appropriate concentration addition of Se will significant increased both the tolerance capability and the nitrite degradation ability of L.P2.3. In this study, antioxidant activity of Se-enriched lactobacillus, which were obtained by direct additive test, was investigated. Results showed that 0~4mg/L selenium concentration help LAB to resist H2O2. Free radical scavenging activities of the cell free extracts are better than complete cells. ·OH- radical scavenging of the cell free extracts of Se-enriched lactobacillus are increased by 17.58%~4.55%, but the DPPH radical scavenging ability was reduced. What is important is that the anti-lipid peroxidation of Se4.0 is 3.02 times as than Se0. The oxidation mechanism of greases was introduced. Total reducing power of cell free extracts were enhanced due to Se. The SOD activities of Se2.0 and Se4.0 were 2.14 and 1.72 times as much as Se0. GSH-Px activities increased with the increase of Se concentration. The trend of SOD and GSH-Px activities is not the same. The iron ion chelating ability of Se2.0、Se4.0、Se6.0 were much better than Se0.