Abstract:

 In this study, 16 strains isolated from Inner Mongolian dairy tofu were identified by 16S rDNA sequence
analysis. Of these, nine strains were identified as Pediococcus acidilactici, five as Enterococcus faecium, one as
Lactobacillus plantarum and one as Lactobacillus rhamnosus. The screened strains were further investigated for their
tolerance to simulated artificial gastric juice and bile salt, hydrophobicity, in vitro cholesterol-reducing and antioxidant
activity. The results showed that L. plantarum M1-2 and L. rhamnosus M6-1 had high tolerance to simulated gastric juice;
E. faecium M7-1, M8-1 and M8-2 were highly tolerant to bile salt; L. plantarum M1-2 and L. rhamnosus M6-1 exhibited
a higher hydrophobicity for methylbenzene and hexadecane than other screened strains. The results of in vitro functional
characterization showed that E. faecium M1-1, L. plantarum M1-2, P. acidilactici M1-3 and M2-1 exhibited a high
cholesterol-reducing ability with an in vitro cholesterol removal rate more than 30%. L. rhamnosus M6-1 showed the highest
tolerance to hydrogen peroxide, hydroxyl and DPPH radical scavenging activities. In conclusion, L. plantarum M1-2 and
L. rhamnosus M6-1 showed good probiotic potential among the screened strains, and thus they can be considered as potential
probiotics to be applied in functional foods.

Key words: dairy tofu, lactic acid bacteria, probiotic, cholesterol-reducing, antioxidant