| 18 strains of lactic acid bacteria separated from the natural fermented dairy products of Siziwang and Damao banner pastoral areas in Inner Mongolia were investigated in the present study. The experiment of physiological and biochemical identification were carried on to study these strains. The tests initially confirmed that M23, M31, M35, M46, M47, M49, M50, B13, B18, B21, B28, B39 and B97 belonged to Lactobacillus. M22, M33, B4, B26 and M41 belonged to Lactococcus. Experiments of 16SrRNA sequence analysis and the physiological and biochemical identification were carried on 7 selected strains. The results showed that strain M35 belonged to lactobacillus plantarum, M50 belonged to Lactobacillus johnsonii, M22 and M33 belonged to Enterococcus durans, and M41, B4, B26 belonged to Enterococcus faecium.Double dilution method were used to determinate the 18 strains’minimum inhibitory concentration (MIC) of three kinds of fluoroquinolone drugs (Levofloxacin, Norfloxacin and Ciprofloxacin) which were widely used in clinical. The results indicated that only strain M22 showed sensitive to the 3 kinds of fluoroquinolone drugs while the other strains showed different degrees of drug resistance. The rates of drug resistance was as high as 94.4%.Extraction of plasmids and plasmids resistance genes qnr were carried out among the 7 drug resistant strains. Then the results were examined by electrophoresis analysis. The results of electrophoresis analysis showed that about 10 kb plasmid DNA were found in 6 strains except strain M50 while the resistant plasmid DNA qnr were not detected in the 6 strains.Plasmid restructuring were conducted of the 6 strains, then we carried on drug resistant tests of the recombinant strains.The drug resistance factor were extracted and conversed of the 7 drug resistance strains, then drug resistant tests of the conversed strains were carried out.The results indicated that recombinant strains were sensitive to the three kinds of drugs while the conversed strains showed different levels of drug resistance. It can be concluded that the fluoroquinolone drugs resistance has no direct relationship with the plasmids of lactic acid bacteria. Thus the drug resistance will not be transmitted through the plasmid gene qnr while it may be spread through the other drug resistance factor. |
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