Probiotic and antioxidant properties of selenium-enriched Lactobacillus brevis LSe isolated from an Iranian traditional dairy product

The present study was designed to isolate a highly selenium-tolerant lactobacillus strain from an Iranian traditional dairy product named as Spar. Different criteria such as tolerance to the low pH, simulated gastric juice (SGJ), simulated intestinal juice (SIJ) and bile salts tolerance as well as Caco-2 cell adhesion assay were examined to evaluate the probiotic potentials of the selected isolate. Furthermore, the antioxidant properties of the isolate cultivated in medium containing and free of SeO32− ions were evaluated using DPPH scavenging and reducing power assays. The isolate was identified using conventional identification and 16S rDNA gene sequencing methods as Lactobacillus brevis LSe. The obtained results showed that the isolate was able to tolerate high concentration of sodium selenite (3.16 mM). By decreasing the pH of the SGJ from 6 to 3, the survival percent of L. brevis LSe was not significantly changed over the time (p > 0.05). In addition, the survival percent of the isolate in the SIJ (pH 6 and pH 8) was not statistically altered after 3 h, 6 h and 24 h of incubation (p > 0.05). In the presence of bile salts (0.3% and 0.6%) the survival rate of L. brevis LSe was not significantly decreased (p > 0.05). L. brevis LSe also demonstrated the satisfactory ability to adhere to Caco-2 cells which were similar to that of the reference strain L. plantarum. The obtained results of antioxidant evaluation showed that L. brevis LSe containing elemental Se exhibited significantly higher radical scavenging ability (36.5 ± 1.31%) and reducing power (OD700, 0.14) than L. brevis LSe cultured in selenite-free medium (p < 0.05). To sum up, further investigations should be conducted to merit the probable potential health benefit of Se-enriched L. brevis LSe and its application as Se-containing supplements or fermented foods.