抗生素胁迫条件对土壤微生物生态结构的影响及耐药细菌污染控制初步探讨

【作者】 王凯；

【导师】 胡健；

【作者基本信息】 扬州大学 ， 土壤学， 2011， 硕士

【摘要】 目前,由于抗生素选择压力造成的致病细菌耐药性提高以及耐抗机制的丰富,对人类治疗感染提出了严峻考验。制药、医用废水中含有大量抗生素,它们的无组织排放以及含大量抗生素的牲畜粪污在农业上的施用,直接破坏了环境微生物生态系统。另外,长期的抗生素污染物的残留有可能引起土壤等环境微生物耐药性的变化。本文综合运用传统的土壤化学和微生物生态学方法研究手段,并借鉴环境影响评价方法,分析了四环素在土壤中的环境行为；抗生素胁迫环境对耐药细菌产生和存在的影响；畜禽散户养殖带来的耐药细菌环境风险以及对控制耐药细菌污染扩散的初步探讨。研究结果如下：1、四环素在3种供试土壤(高沙潮灰土、水稻土、废黄河冲积沙性土)中的吸附均符合Freundlich模型和Langmuir模型,对2种模型均表现为良好的线性关系,属于物理吸附过程。3种土壤中四环素的吸附行为存在较大的差异,由Langmuir方程计算得到3种土壤的四环素最大吸附量(Qm值)分别为砂壤土817.7mg/kg、壤土1057.4mg/kg和砂土188.7mg/kg,与Kf值变化趋势一致。二者极显著相关(p≤0.01),相关系数r为0.997。土壤理化性质对诺氟沙星的土壤吸附影响主要表现为与pH的极显著负相关,与其他性质的关系不明显。2、通过对室外培养土柱的数据分析,发现环境中加入一定浓度的抗生素,形成抗生素胁迫环境后,土壤中耐药细菌数量会增加。环境中抗生素在淋洗和自然降解的作用一下,浓度不断降低,土壤耐药细菌数量会随之减少,但存在滞后现象,且浓度越高越明显,持续时间越长。3、通过阅读文献和田野考察,运用环境影响评价的方法对畜禽散养和规模化养殖两种养殖方式的特点、抗生素的使用和管理方式以及抗生素污染环境影响的特点进行了分析,并做出权重分析表。发现畜禽散户养殖是一个重要的抗生素污染及其带来的耐药性细菌污染的重要源头,比起规模化养殖更容易对人类的健康造成危害。4、通过对抗生素残留在土壤中的吸附迁移,以及抗生素胁迫环境下耐药细菌群落结果变化情况的研究以及阅读相关文献,我们发现常用抗生素,如四环素、土霉素、诺氟沙星等被pH值较高的土壤吸附的能力较弱以及细菌耐药性随环境抗生素含量降低而消弱的特性,可以通过碱液淋洗残留有抗生素的土壤,降低与人类活动密切相关的上层土壤中抗生素的含量,来消弱或消除其中的耐药基因。实验结果表明,碱液淋洗能快速的降低土壤环境中抗生素的浓度,降低抗生素胁迫的作用,从而减少土壤环境中的耐药基因给人类健康带来的威胁。更多还原

【Abstract】 At present, the choice pressures caused by antibiotics cause the increase of the antibiotic resistance and the diversification in resistant bacteria and resistant mechanism, they are severe test to human antiinfection treatment[1]. On the other hand, wastewater and medical wastewater containing antibiotics pharmaceutical are discharged into environment. As well as agricultural use of livestock excreta containing a large number of antibiotics, which directly cause the damage of environmental microbial ecosystem. Mean while because of the long-term antibiotic residues may cause Microbial resistance changes in the environment such as soil environment.In this paper, the integrated use of traditional methods of soil chemistry and microbial ecology research tools, and learn from the environmental impact assessment method, analysis of antibiotic residues in livestock and poultry free-range drug resistance bacteria and the resulting environmental impact of pollution; antibiotics into the soil environment, on microbial ecology and environmental impact of microbial drug resistance; and the resistance bacteria on the initial spread of pollution control were discussed. The results are as follows:1. Tetracycline at the3soils (high sand influx soil, paddy soil, waste of the Yellow River alluvial sandy soil) in the adsorption conformed to Freundlich model and Langmuir model, two models showed a good linear relationship as belonging to physical adsorption process. There is a big difference in soils about adsorption of tetracycline, calculated by the Langmuir equation3the maximum adsorption capacity of soil of tetracycline (Qm value) were sandy loam817.7mg/kg, loam1057.4mg/kg and sand188.7mg/kg, the same trend with the Kf value. Both highly significant (p≤0.01), correlation coefficient r was0.997. Soil properties on adsorption of norfloxacin major impact of soil pH was highly significant and negative correlation, the relationship with other properties is not obvious. 2. Through the soil column on the outdoor culture of data analysis, we found the environment by adding a certain concentration of antibiotics, the formation of antibiotic stress environment, the soil will increase the number of resistant bacteria. Environment and natural degradation of antibiotics in the role of leaching look, continue to lower the concentration, the soil will decrease the number of resistant bacteria, but there are hysteresis, and the higher the concentration, the more obvious the longer the duration.3.By reading literature and field observation, the use of environmental impact assessment methods and large-scale backyard poultry farming characteristics of the two farming methods, antibiotics and antibiotic use and management characteristics of the environmental impact of pollution in the analysis, and make weight analysis table. Found that livestock farming is a major retail antibiotic resistance caused by pollution and an important source of bacterial contamination, compared to large-scale farming more easily cause harm to human health.4. Antibiotic residues in soil by adsorption in the migration, as well as antibiotic resistant bacteria under stress changes in the results of the research community and reading the literature, we found that commonly used antibiotics such as tetracycline, oxytetracycline, norfloxacin, etc. are higher soil pH value of the weak adsorption and bacterial antibiotic resistance decreased with the environment and the weakening of the characteristics of alkaline leaching through the soil residues of antibiotics, reducing closely related to human activities of antibiotics in the upper soil content, to weaken or eliminate one of the resistance gene. Experimental results show that alkali leaching can quickly reduce the concentration of antibiotics in soil, reducing the role of antibiotics, stress, thereby reducing the soil resistance gene in the human health threat.更多还原