Study On Probiotic Properties And Safety Of Bacteria Producing Conjugated Linoleic Acid

By measuring related indexes, such as adhesion ability, gastrointestinal tolerance and so on, probiotic properties and safety of 32 lactic acid bacteria producing conjugated linoleic acid isolated from traditional fermented cream products in Xilingol League of Inner Mongolia were studied. The results were showed as follow:1. The auto-aggregation and hydrophobicity of strains were detected.10 strains with high adhesion were screened out from the 32 strains, which were AS9, AS8, LX5, HH7, HH4, HS10, LX4, HS8, LX6, HS4, respectively. In which, strain LX5, AS8 and AS9 cells were closely stacked under scanning electron microscope, which showed strong auto-aggregation.2. Strain AS8, HH7 and AS9 had higher tolerance at pH2.5. Strain HH7, LX5 and AS8 had higher tolerance of model bile. Strain AS8, HH7 and AS9 had strong tolerance to simulated gastric fluid added pepsin. Strain AS8, LX5 and AS9 had strong tolerance to simulated intestinal fluid added trypsin.3. The inhibition ability of the 10 strains was determined with Escherichia coli and Staphylococcus aureus as indicator bacteria. The results showed that, HH7 had the most obvious inhibitory effect on E.coli, while AS8 had the worst. HS4 had good inhibition ability to Staphylococcus aureus, while LX6 had the worst.4. The tolerances to common antibiotics of the 10 strains were studied with the Kirby Bauer disk diffusion method. The results showed that, LX6 had the strongest tolerance to tetracycline, while AS8 had the worst. HS8 had the strongest tolerance to Penicillin, while HH7 was the weakest. AS8 had the strongest resistance to Acetyl Spiramycin, while LX6 was the weakest.5. All the 10 test strains could produce tyramine in different degrees, but could not produce histamine. The test of nitro reductase all showed negative, so they did not have the nitrft reductase producing ability. The test of azo reductase all showed negative, so they did not have the azo reductase producing ability.6. In the animal experiment, the weights of mice intragastric administration with LX5, HH7 were significantly increased than control group (p<0.05). The fecal microflora showed that, with intragastric administration for 8 days, the number of Lactobacillus and Bifidobacterium in LX5 group and HH7 group intestinal flora were markedly increased, and the harmful bacterias were markedly decreased(p<0.05). It indicated that the LX5 and HH7 could promote the growth of beneficial bacteria and played an important role in the regulation of intestinal bacteria groups. The weights of mice intragastric administration with AS8 were increased slowly, and the number of viable bacterias in intestinal tract was not obviously increased. The liver and spleen of mice intragastric administration with LX5, HH7, and AS8 had no significantly differences compared with the control group.