Safety Assessment Of Lactobacillus Strains DM9054 And DM9057

Objective: In recent years,much more attention are paid to the benefits of probiotics.Most Lactic acid bacteria strains exert their functional effects at the aspects of alimentology and medical science as food and medicines.Although a large majority of the LAB strains are safe,some studies proved that LAB can be found that caused some imflammation occurred.The subject of safety arouses attention.The LAB DM9054 and DM9057 are both isolated from the pickles and respectively pocess the cholesterol-lowering and blood pressure conquering function.The two strains have strong functions and good characteristics screened by a series of selection and evaluation tests,and are appropriate to applied in the field of manufacture.The purpose of our study is to assess the safety of the two strains as well as providing the references for food and medicine production.Methods:(1)Acute toxicity test:mice were divided into groups and administrated with a large dose of experimental strains liquid culture,then observed the change of their habitus and mental state.Anatomized the mice at the end of observation to detect whether the structural disease happened.(2)Drug resistance assess tests:the antibiotic susceptibility test performed to detect the level of antibiotic sensitivity and agarose gel electrophoresis test to identify whether the transferable resistant plasmid exist.(3)Organism indicators assess tests:after administrated and intraperitoneal injected with experimental strains,measure the concentration of MDA,SAA and total liver GSH by the reagent assay kits.Two experimental strains cultured on the MRS medium added with taurodeoxycholic acid sodium salt in order to detect the production of bile salt hydrolase.(4)Harmful metabolites production assess tests:using reagent assay kits to detect D-lactic acid,nitroreductase in the DM9054 and DM9057 24 hours cultured liquid MRS mediums.Experimental strains are cultured on the BASM mediums to ensure whether the experimental strains produce amino acid decarbosylase.(5)Other assess tests:observe whether there is occurrence of hemolysis when experimental strains cultured on the blood agar for 20 hours.Sacrificed the experimental animals administered DM9054 and DM9057 for 20 days,cultured the organ hemogenates on MRS medium and observe if there is a bacteria translocation taken place.Results:After administered a large dose of DM9054 and DM9057,there is no influence on the weight,habitus or mental state;both of the two strains have resistance to part of the antibiotics,but do not possess the transferable plasmids;the change of MDA,GSH and SAA concentration has no differences between control and LAB-treated group,the strains product D-lactic acid but no bile acid hydrolase,nitroreductase and amino acid decarboxylase;the two strains have no hemolysis effect or translocation phenomenon occurred.Conclusion:According to the results aboved,it presents that both the strains DM9054 and DM9057 are safe in general,which can exert their cholesterol-lowering and conquering blood pressure function as food and medicine in future manufacture.