Influence Of Manure Application On Population Size Of Antibiotic-Resistant Bacteria And Pathogens In Field

As large quantities of antibiotics were used in animal breeding industry, antibiotic-resistant bacteria and pathogens might be transmitted to the environment through manure fertilization,which might cause risks to human health.Therefore, the veterinary antibiotics ecological risk assessment has become one of the research focus all over the world. In the article, the changes of the number of antibiotic-resistant bacteria and pathogenic bacteria in the wheat field with different manure were detected to evaluate the ecological and environmental risks of fertilization of manure from intensive animal breeding plants.In the article,changes of the number of antibiotic-resistant bacteria and pathogenic bacteria in wheat soil with different manure were detected. The results showed that the number of tetracycline or ampicillin or sulfanilamide resistant bacteria and the proportion of antibiotic resistant bacteria to total cultivable bacteria in topsoil from the spots treated with the pig manure and with high commercial manure is more than the plots treated with rape seed cake during the study. Influence of commercial manure application on soil microorganism is less than that of pig manure application. One month after manure application, the most propable number of total/feacal coliform is also higher in topsoil from the spots treated with pig manure and with commercial manure than in the spots treated with rape seed cake.Three months later, the difference of most propable number of total/feacal coliform between all wheat experimental spots were not observed.In the article,changes of the number of antibiotic-resistant bacteria and pathogenic bacteria in paddy field with different manure were detected. The results showed that,a week after fertilization,the number of cultivable bacteria and tetracycline or ampicillin or sulfanilamide antibiotics resistance bacteria were significantly higher in topsoil and surface water of paddy experimental plots treated with pig manure and with commercial manure than in that of the plots treated with rape seed cake,but the proportion of antibiotic resistant bacteria to total cultivable bacteria did not increased remarkably. One month after fertilization, the number of cultivable bacteria were still more in surface water of paddy plots treated with pig manure and with commercial manure than in that of paddy plots treated with rape seed cake,but no obvious differences in antibiotics resistance bacteria among spots. High manure application could increase the number of cultivable bacteria and antibiotics resistance bacteria in paddy field but did not relate to the proportion of antibiotic resistant bacteria to total cultivable bacteria. Manure application could also enhance the most propable number of fecal coliform in paddy field but few fecal coliform survived a month after fertilization.More than 360 coliform and 50 E.coli. strains mainly isolated from four different farmland were examined for resistance to 11 antibiotics using Kirby-Bauer disk-diffusion method. More resistance patterns of coliform were found in topsoil from spots treated with high commercial manure. Environmental E.coli strains and those from manure could be separated well into different clusters shown by the dendrogram using SAS software to do the cluster analysis. The results also indicate some E.coli strains residue in soil because of manure application.The farm investigation showed that the number of antibiotics resistance was about 10 times higher in soil treated with manure for a long period than in that without manure application. Percentage of Gram-positive bacteria was lower distinctly in soil treated with manure than in that untreatment. The number of cultivable bacteria was also larger in manure application soil,but the kinds of morphology of microorganism colony in EMB plate decreased compared to control soil. Proportion of Tetracycline or Chloramphenicol or Kanamycin or Streptomycin or Gentamicin resistance to total cultivable bacteria increased in soil after a long period treatment with manure from animal breeding industry.