| Recent years, Guizhou government has attached importance to the development of Sansui duck breeding and brought economic benefit for the local farmers. The environment of duck farm and surroundings are polluted by a lot of excrement during the breeding process.Meanwhile, bacteria in environment also affect the ducks health. Using of antibiotics long-time resulted in drug resistant appearing in bacteria, which troubled the livestock and poultry breeding industry. To understand bacterial species of duck farm environment and find out the reasons why the duck got sick. To identify the bacterial species of the environmental soil and water in partial duck farms. Traditional method was adopted in the isolation and identification of bacteria which in the internal organs of the sick duck. The survey of drug-resistant, the detection of antibiotic resistant gene and the elimination of resistant plasmid were carried out in this trial. All these studies will provide the theoretical evidences for disinfection control of environmental pathogenic microorganism and prevention of bacterial disease in duck farm.1. The analysis of bacterial community structure of large-scale duck farm: The environmental soil and water samples were collected from partial duck farms in Guizhou. The total DNA of samples were extracted by the kit, and the bacterial 16 S rDNA V3 region was amplified by PCR. Then the PCR products were analyzed by DGGE, and the DGGE fingerprints were analyzed by Quantity One software. Finally the target fingerprints were recycled and sequenced.(1)There were 5 bacteria categories in the soil samples of environment in duck farms, they were α- Proteobacteria, β-Proteobacteria,Bacteroidetes,Actinobacteria, Acidobacteria, Firmicutes and uncultured bacterium. The proportion of Firmicutes was the most, about 44.19 % of all. Proteobacteria was in the second place took up 20.93 %, and uncultured bacterium was 18.60 % Bacteroidetes and Actinobacteria were in the same stage about 6.98 % of the total. Acidobacteria was the last one with 2.33 % of all.(2)There were 3 bacteria categories in the water samples, they were Proteobacteria, Firmicutes,Acidobacteria and uncultured bacterium. Proteobacteria was the dominant in proportion of56.67 %. Firmicutes was 10.00 % and Acidobacteria was the least in proportion of 6.67 %.The rest was uncultured bacterium with the proportion is 26.67 %.2. The isolation and identification of bacteria from Large-scale Duck Farm and pathogenicity test: Internal organs of sick Duck were collected from partial duck farms to isolate and identify bacteria through blood nutrient agar culture-medium, biochemical identification or PCR identification were carried out after pure culturing of suspicious colony.Pathogenic experiment was carried out after randomly selecting the main isolated bacteria. A total of 137 strains bacteria were isolated from sick ducks with internal organs, including 56 strains Escherichia coli, accounting for 40.88 % of the total isolated bacteria; 47 strains Staphylococcus, accounting for 34.31 %; 14 strains Riemerella Anatipestifer, accounting for10.22 %; 9 strains Proteus, accounting for 6.57 %; 4 strains Yersinia and 4 strains Citrobacter,accounting for 2.92 %; 3 strains Pseudomonas, accounting for 2.19 %. Pathogenic trial in mice showed that Escherichia coli and Staphylococcus caused the trial mice death,respectively the fatality rate were 23.3 %(7/30) and 16.7 %(5/30), while the Riemerella Anatipestifer could’t caused the trial mice death, the fatality rate was 0(0/9).3. The resistance investigation and control research of pathogenic bacteria from Large-scale Duck Farm: Adopting disk diffusion method to analyze the antibiotic resistance of 15 strains Escherichia coli, 15 strains Staphylococcus and 3 strains Riemerella Anatipestifer. The Escherichia coli were detected antibiotic resistance gene and eliminated antibiotic resistance plasmid. The results showed that the Escherichia coli antibiotic resistant rate as high as 100 %(15/15) to 10 kinds of antibiotic among 20 kinds of antibiotics, the Staphylococcus antibiotic sensitive rate as high as 100 %(15/15) of 4 kinds of antibiotics,while the Riemerella Anatipestifer antibiotic resistant rate higher than 50 % of the most of antibiotics. According to the antibiotic resistant gene testing of the Escherichia coli results can be seen that the TEM antibiotic resistant gene rate was 46.7 %(7/15) and the CTX-M antibiotic resistant gene rate was100 %(15/15), the SHV antibiotic resistant gene wasn’t detected. The bacteria resistant plasmid of Escherichia coli were lost when the best concentration of SDS was 0.5 % alternating with 43 ℃ high temperature to process.In conclusion:The environmental soil bacteria from partial duck farms in Guizhou were derived from Proteobacteria, Bacteroidetes, Actinobacteria, Acidobacteria, Firmicutes and the uncultured bacterium. The environmental water bacteria from the same duck farms were derived from Proteobacteria, Firmicutes, Acidobacteria and the uncultured bacterium. A total of 7 genera 137 strains isolated from internal organs including of Escherichia coli,Staphylococcus, Riemerella Anatipestifer and some of other bacteria. The main isolation bacteria had varying degrees pathogenic to health BALB/c mice. The main isolation bacteria existed extensively drug-resistant to test antibiotics. The bacteria resistant plasmid of Escherichia coli could be eliminated through handling by high temperature and SDS. |
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