| Probiotics belongs to the kind of viable microorganisms benefiting host’s healthy, i.e. prevention of diarrhea and allergy, alleviation of lactose intolerance, enhancement of human immunology, hypocholesterolemic effect, prevention of cancer and inhibitory of growth of tumor cells, etc. Currently, probiotics has been widely used in the area of food and drug, and 80% of probiotic food belongs to dairy products.The number and variety of probiotics in product labeling and the actual survival have been concerned. In China, few reports showed about the number and species of strains in probiotic products. In this study, viable cell counting method and DGGE approach were combined to preliminarily investigate the bacterial number and species in 28 commercial probiotic products (20 yoghurts and 8 drugs), and also bacterial characteristics of isolates from yoghurt were compared with a control strain of Enterococcus faecalis in human feces.The results indicated that though the viable number of probiotics was higher than 6 Lg CFU/mL in most investigated probiotic products. However, the amount of Lactobacillus and Bifidobacteria possed a low percentage dominnant in total cell counts. DGGE analysis and sequencing results showed that the labled Bifidobacteria was not detected in all products while the occurrence of labled Lactobacillus was only detected in some products. Furthermore, unlabled E. faecalis was also detected among most products. Unfortunately, unlabled Enterobacter sp. was detected from some products, some other pathogens i.e. Staphylococcus epidermidis, Klebsiella sp., Serratia sp were detected. Compared with yoghurt, the situation of drug was better, but some problems had still been found. DGGE analysis indicated the occurrence of labled strains in drugs, however, some unlabled strains, i.e., L. lactis, L. helveticus, L. casei, L. plantarum, L. bulgaricus, L. jensenii, B. animalis, were also detected using DGGE.In the study,8 strains were isolated and identified from yoghurt (L. bulgaricus YH001, B. longum YH002, S. thermophilus YH003, Bifidobacterium sp. YH004, B. lactis YH005, L. casei YH006, E. faecalis YH007 and L. acidophilus YH008) and their probiotic properties had been fully studied. The results indicated that most of the 8 stains showed antagonistics against pathogens and intolerance of acid and bile. Among the strains, L. bulgaricus YH001 and B. lactis YH005 showed wide antagonistic activity against the 8 testing pathogens, moreover, the survival cells of L. bulgaricus YH001 and B. longum YH002 in pH 1.5 and 0.3% of bile concentration in incubation system can reach the level of 5 Lg CFU/mL. Gernerally, the properties of isolates were worse than the reference stain of E.faecalis.The study has provided reference data for a comprehensive understanding of the quality and safety of probiotics products in China, and a future guidance to the product development. |
PDF Full Text Request