Screening and identification of selenium-enriched purine-lowering Lactobacillus plantarum and Lactococcus lactis with high stress tolerance and antioxidant capacity

Hyperuricemia and selenium (Se) deficiency have become world wide health issues, necessitating the development of new technologies for the prevention of hyperuricemia and daily Se supplementation. This study explored a feasible way by providing new lactic acid bacteria (LAB) with both Se-enrichment and purine-lowering functions. The expected LAB were firstly screened out and identified from fermented tea grown in seleniferous areas by a five-step screening method. Among thirty-six candidate strains exhibiting superior Se-enriched ability, seven of them showed excellent uric acid absorption, in vitro xanthine oxidase and uric acid oxidase activities. In particular, Lactobacillus plantarum L123 and Lactococcus lactis L126 degraded inosine and guanosine to hypoxanthine and guanine with degradation rates of 100%, 96.88% ± 0.33% and 93.61% ± 1.06%, 81.15% ± 1.83%, respectively, and metabolized the substrates of hypoxanthine, xanthine and uric acid into the final product allantoin. Their clearing rates of three free radicals (DPPH, •OH and ABTS+• free radical) were higher than 94% after reaction for 30 min. More than 85% of L123 and 50% of L126 could survive at pH 1.5 for 3 h, while their Se-enriched counterparts showed more enhanced acid tolerance. Both L123 and L126 with or without Se-enrichment tolerated 0.5% bile salt with survival rates above 80%. These Novel LAB provide a promising avenue for the development of new health food and pharmaceutical products that combine Se supplementation with hyperuricemia treatment.