Effects of veterinary medicines in manure on the abundance and transfer of bacterial antibiotic resistance genes in soil: importance of the rhizosphere and of prepeated manure applications

在该项目的第一阶段，我们表明，土壤施肥与粪肥含有抗生素提高了抗生素耐药基因的丰度和它们的可转移性，并确定了质粒类型，在粪肥和土壤细菌之间的耐药基因的水平传播中起着重要作用。在第二阶段，我们的目标是阐明含有兽药的粪便的土壤施肥效果是否受到根际和重复施用粪便的影响。这将在联合土壤围隔生态系统和实地实验中进行研究。将在微观世界中以低空间和时间分辨率对根际效应进行分析和建模（A1，C）。将在中心田间试验的样品中研究通过重复施用粪肥在本体和根际土壤中抗性种群的积累。将通过真实的时间PCR获得总群落（TC）-DNA中抗性基因和质粒丰度的定量数据。这些数据将与土壤中抗生素化合物的可提取和不可提取量相关，以阐明其生物利用度和选择力。我们的目标是确定和量化粪肥和土壤中的抗性质粒宿主，以便将其生境特异性命运和种间质粒转移纳入数学模型（C）。

In the first phase of this project we showed that soil fertilization with manure containing antibiotics enhanced the abundance of antibiotic resistance genes and their transferability, and identified a plasmid type that plays a major role in horizontal spread of resistance genes between manure and soil bacteria. In the second phase we aim to elucidate if the effects of soil fertilization with manure containing veterinary medicines are influenced by the rhizosphere and by repeated application of manure. This will be investigated in joint soil mesocosm and field experiments. Analysis and modeling of rhizophere effects at a low spatial and temporal resolution will be performed in microcosms (with A1, C). Accumulation of resistant populations in bulk and rhizosphere soil by repeated manure application will be investigated in samples from a central field experiment. Quantitative data on the abundance of resistance genes and plasmids in total community (TC)-DNA will be obtained by real time PCR. These data will be related to extractable and non-extractable amounts of antibiotic compound in soil to clarify their bioavailability and selective force. We aim to identify and quantify the hosts of resistance plasmids in manure and soil, in order to incorporate their habitat-specific fate and inter-species plasmid transfer into a mathematical model (C).