| Antibiotics have played an important role in the development of livestock farming,but only a small amount of antibiotics could be absorbed by animals,and most of antibiotics were excreted from the body by metabolic pathways.The usages of antibiotics have induced the appearance of antibiotic resistance bacteria and antibiotic resistance genes,which could excreted from the body into the environment.Aboriginal bacterias that grow in the environment have gotten the antibiotic resistance genes under the selection pressure of antibiotics and the Horizontal gene transfer of antibiotic resistance gene,these have spread the antibiotic resistance genes to other bacteria groups.Furthermore,In some degree transport of antibiotic resistance genes in the environment could endanger the safety of food,drinking water and even public health.In this dissertation,we selected dairy farms in Xinjiang and Qinghai province which have different climatic conditions,We comprehensively analyzed the dairy farming environment and the distribution of ARGs and drug-resistant bacteria during the process of fecal processing by using anaerobic fermentation,composting and organic manure processing as the research object.The main tests and conclusions are as follows: 1.The results showed that the resistant strains in dairy farms were mainly concentrated in Escherichia,Pseudomonas,Enterococcus,Streptococcus,Proteus,Staphylococcus,Acinetobacter,Alcaligenes Genera,Bacillus and so on.The resistance rates of the samples of compound sulfamethoxazole,vancomycin,oxacillin and erythromycin were more than 90%,and the resistance rates of kanamycin,tetracycline and florfenicol to the bacteria in the samples were 60% to 70%.The resistance rate of ciprofloxacin was 35%.The drug genotypes of kanamycin,erythromycin,tetracycline,florfenicol and compound sulfamethoxazole were the same as their drug resistance phenotypes,and The results also show samples both had high drug resistance rates and gene detection rates;The drug resistance rate of the ciprofloxacin was the lowest or no,and among the 6 genes detected in the experiment,the detection rates of 5 genes were low or no,the detection rate of aac(6)-Ib-cr was up to 95%;oxacillin and vancomycin both had a high rate of resistance,but the drug resistant gene was not detected.2.The fecal sedimentation stage in the anaerobic fermentation process had a significant impact on the number of resistant bacterias,while others had little effect in other stages.The composting process not had obvious elimination of drug resistant bacterias,and the situation of composting for 10 days and 20 days had little effect on resistant bacterias.Anaerobic fermentation and composting had no effect on floR,aac(6)-Ib-cr,ermB,sul1,sul2,and aac(6)/aph(2”)genes.Composting treatment had a certain elimination effect on the genes of fexA,gyrB,and ermF.The anaerobic fermentation treatment had a certain elimination effect on the fexA,grlB and ermC genes;it was probably to determine the advantages and disadvantages of the two faecal treatment methods by the removal effect.3.The manure treatment process changed the microbial group structure of drug-resistant bacterias,and reduced the types and number of drug-resistant bacterias,as a result,the number of resistant bacterias were reduced by 40%.The manure treatment process had removal effects on the genes of fexA,cfrB,ermC,tetB and tetC,and had no removal effects on genes floR,ermB,ermF,tetM,sul1,sul2 and aac(6)/aph(2”). |
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