| Lactobacillus fermentum have been used as edible strains in food production and processing for many years. In the present study, isolated from traditional food products of Inner Mongolia, Yun Nan and Mongolia etc.,150Lactobacillus fermentum strains were screened In vitro for evaluating probiotic characteristics including the acid resistence, simulated gastrointestinal fluid transporting tolerance, antibacterial activity, aggregating and hydrophobic properties.The results showed that the40strains of high acid resistance were screened from the acid resistance test (after72h at pH3.0acidic conditions cultivating, the△OD600＞0.700). Furthermore,12gastric juice-tolerant strains were screened out by simulated gastric fluid test(cultivating3h in simulated gastric environment at pH2.5, the survival rate of bacteria counts is above50%).Through transporting from pH2.5simulated gastric fluid to pH8.0simulated gastrointestinal fluid and bile salt tolerance test, two favorable strains (L. fermentum IMAU70161and L. fermentum IMAU70013) could be tolerated the bile salts at the concentration of2.0%environment.The L. fermentum IMAU70161was considered as slightly bile salt-tolerant strain (the lag time for0.73h in0.3%bile salts), while L. fermentum IMAU70013was bile salt-sensitive strain (the lag time for1.08h in0.3%bile salts). But no significant difference (P＜0.05) was observed in lag time between two strains.Further results showed that the survival rate of the L.fermentum IMAU70161(33.71%±0.07) was significantly higher than L.fermentum IMAU70013(15.28%±0.01) by transporting from pH2.0to pH8.0simulated gastrointestinal fluid transfer tolerance test, suggesting a strong gastrointestinal fluid transport tolerance of L.fermentum IMAU70161. These two strains were of broad-spectrum resistance to the five target pathogens, which inhibitory area of L. fermentum IMAU70013was significantly higher than the L. fermentum IMAU70161(P＜0.05).The auto-aggregation property of L. fermentum IMAU70161was significantly higher than that of L. fermentum IMAU70013under cultivation at20℃for20h (84.45±0.60%vs30.84±1.01%, P＜0.05). The co-aggregation property of strain L. fermentum IMAU70161was significantly higher than that of L. fermentum IMAU70013.However, the surface hydrophobicity rate of L. fermentum IMAU70013was higher than L. fermentum IMAU70161(70.06±2.02%vs58.89±1.37%, P＜0.05).Considering all these, L. fermentum IMAU70161and L. fermentum IMAU70013can be used for probiotic potential. |
