In vitro evaluation of probiotic potential of Lactobacillus cultures of human origin capable of selenium bioaccumulation

•Probiotic characterization of Lactobacillus cultures of human origin.•Lactobacillus cultures having high selenium bioaccumulation ability.•Prolific cultures can be used for production of functional food and nutraceuticals.

The probiotic potential of 5 food grade Lactobacillus strains, of human origin namely Lactobacillus fermentum (S23), Lb. fermentum NCDC77 (S8), Lb. fermentum (S25) and Lb. plantarum (S1), capable of selenium bioaccumulation (in previous studies), was investigated. The cultures, S8 and S23 maintained elevated cell numbers under conditions simulating passage through the human gastrointestinal tract, showing ability to survive in the presence of simulated gastric juice at pH 2. These cultures also survived in the presence of simulated intestinal juice with 1% bile salts. The cultures showed variable and strain dependent cell-surface hydrophobicity and auto-aggregation ability. The cultures were assayed for susceptibility to 20 antibiotics and found susceptible to 14 out of 20 antibiotics while showed variable resistance to remaining 6 antibiotics. S8 and S23 cultures showed superior antibacterial activity in comparison to remaining 3 cultures. These findings suggest that Lb. fermentum NCDC77 (S8) and Lb. fermentum (S23) cultures, endowed with the ability to accumulate high amount of selenium, exhibited high resistance against low pH and bile. Moreover, these cultures possessed adherence and auto-aggregation properties with minimum resistance to antibiotics and hence could be exploited for the development of selenium enriched functional food or nutraceutical as a source of dietary selenium.