Screening of potential probiotic properties of Lactobacillus fermentum isolated from traditional dairy products

Ninety strains of Lactobacillus fermentum which were isolated from traditional dairy products of minority nationalities (53 strains from Tibet, 1 from Inner Mongolia, 7 from Yun Nan and 29 from Mongolia), were evaluated for probiotic potential with the resistance to low pH, simulated gastrointestinal juice, and bile salts. The results showed that 35 strains grew well at acid condition (pH 3.0). Eleven strains were further screened out from 35 strains with high tolerance to the simulated gastric juice (pH 2.5, 3 h of incubation). While in simulated gastric juice (pH 2.0), only F6 (isolated from traditional dairy products in Inner Mongolia) could survive to a rate of 53.7%. Moreover, among 11 Lactobacillus strains, L. fermentum F6 showed good tolerance to bile salt, while L. fermentum IMAU60151, IMAU60083, IMAU20080 and IMAU60120 were poorly presented. Further autoaggregation properties, coaggregation with pathogens and antimicrobial activity of the 11 strains were evaluated. The abilities of coaggregation with pathogens were strain-specific and independent on incubate time. All of the selected strains showed various antimicrobial activities against five food-borne pathogens. F6 possessed the highest ability of inhibiting pathogens. All selected strains showed high autoaggregation percentage after being incubated at room temperature for 20 h. Among the selected strains, F6 showed the best probiotic potential with high tolerance to simulated gastrointestinal juice and bile salts, and broad antibacterial activity. F6 had potential application in functional foods and health-associated products.