Association Of Mutation Patterns In GyrA Genes And Quinolone Resistance Levels In Lactic Acid Bacteria

23strains were isolated from koumiss in Xilin Gol in Inner Mongolia, which were studied by the experiments on some aspects, such as morphology, physiological and biochemical characteristics, molecular biology. The results showed that there were4strains of Enterococcus raffinosus,3strains of Enterococcus durans,3strains of Enterococcus dispar,2strains of Lactobacillus plantarum,2strains of Enterococcus villorum,2strains of Enterococcus gallinarum,1strain of Lactobacillus sake,1strain of Lactobacillus casei,1strain of Enterococcus pseudoavium,4strains were not lactic acid bacteria.The characteristics of physiology and biochemistry and the inhibitory test were studied, the good characteristics were found such as the ability to grow adequately in the condition of6.5%NaCl and pH3.5, thermotolerance, the ability to ferment disaccharide and decimpose starch. The tested bacteria had different degrees of inhibition to Escherichia coli and Enteritidis bacillus, HZ1, HZ15, HZ24, HZ25, HZ26, HZ27, HZ28and NN1also had different degrees of inhibition to Staphylococcus aureus.Lactic acid bacteria using cylinder plate method and the liquid double dilution test to determine the antimicrobial resistance and MICs, The results showed that23strains had different degrees of resistance to Norfloxacin(NOR) and Ciprofloxacin (CIP), the rates were100%, the maximum MICs were larger than237.03μg/mL.The sequences of quinolone resistance-determining region (QRDR) of gyrA were studied, and compared them with Eschericha coli through MegAlign, The results showed that the gyrA of HZ1, HZ15, HZ24, HZ25, NN, NN1, NN2, NN3, ZB and ZBQ had10amino acids were substitute,11amino acids were substitute in LD and14amino acids were mutate in BB. There showed conclusively that only the different substitutions of amino acid can resulted in different levels of quinolones resistance.