Effects of irrigation water quality and soil type on the soil and plant associated microbiome, abundance, diversity and transferability of antibiotic resistance genes in Gram-negative bacteria

在气候变化的条件下，废水再用于农业灌溉是为不断增长的人口节约用水和增加粮食产量的有效途径。在许多国家，对基础设施的投资导致了从使用未经处理的废水灌溉到使用经过处理的废水灌溉的转变。拟议研究单位的SP5将有助于检验以下假设：i)从土壤中释放并被植物吸收的污染物的环境浓度足够高，足以选择抗生素耐药性，并在土壤和植物中引发水平基因转移；ii)土壤类型调节污染物的释放和与抗生素耐药性相关的选择。将处理或未经处理的废水添加到已用未经处理的废水灌溉用于&GT的淡色土、褐土和变性土中的效果；80年来，与革兰氏阴性菌相关的微生物群落组成和抗生素耐药基因(ARGs)以及可移动遗传元件(MGES)的丰度将在基于总群落DNA的联合培养和批量实验中进行测试。对于土壤样本的一个子集，将确定革兰氏阴性细菌之间的水平基因转移(HGT)率。将对分离的肠杆菌(SP6)进行筛选，以确定是否存在可转移的质粒.从土壤中释放的抗生素和消毒剂对InCP-1质粒的动员作用将在卫星实验中进行。在卫星实验中，将携带不含抗生素抗性基因的IncP-1质粒的土壤不动杆菌BD413应用于不同处理的土壤，28天后重新分离，并通过IncP-1质粒筛选获得的ArGs。在种植香菜的整体原状土柱的联合土柱实验中，将研究植物对ARGs的选择和传播以及转移到食物链中的相关性。SP5将评估叶圈和根/根际的微生物群落组成，革兰氏阴性菌的ARGs和MGES的相对丰度，以及革兰氏阴性菌之间的HGT率。SP5为用未经处理的废水灌溉黑钙土进行联合田间试验提供了相同的专业知识和技术；通过将其结果和专业知识与RU其他SP的数据和知识联系起来，并通过集成数学模型(SP 7)，SP 5有助于从机理上理解不断变化的污水灌溉系统中污染物、抗生素耐药性和病原体之间的相互作用。

The reuse of wastewater for irrigation in agriculture is an efficient way of saving water and increasing food production for a growing population under conditions of climate change. Investments in infrastructure cause a shift from irrigation with untreated wastewater to irrigation with treated wastewater in many countries. SP 5 of the proposed research unit will contribute to testing the hypotheses that i) environmental concentrations of pollutants released from soil and taken up by plants are high enough to select antibiotic resistance and trigger horizontal gene transfer in soils and plants and ii) the soil type modulates the release of pollutants and the associated selection of antibiotic resistance.The effect of the addition of treated or untreated wastewater to Leptosols, Phaeozems and Vertisols, that have been irrigated with untreated wastewater for >80 years, on the microbial community composition and the abundance of antibiotic resistance genes (ARGs) as well as mobile genetic elements (MGEs) associated with Gram-negative bacteria will be tested in a joint incubation and batch experiment based on total community DNA. For a subset of soil samples horizontal gene transfer (HGT) rates among Gram-negative bacteria will be determined. Isolated Enterobacteria (SP 6) will be screened for the presence of transferable plasmids. The mobilization of ARGs to InCP-1 plasmids due to selection by antibiotics and disinfectants added with wastewater and released from soil will be tested in a satellite experiment, in which the soil bacterium Acinetobacter baylyi BD413 carrying IncP-1 plasmids without antibiotic resistance genes will be applied to the differently treated soils, re-isolated after 28 days and screened for acquired ARGs by IncP-1 plasmids.The relevance of plants for the selection and spreading of ARGs and the transfer into the food chain will be investigated in the joint soil column experiment with monolithic “undisturbed” soil columns planted with cilantro (Coriandrum sativum). SP 5 will assess the microbial community composition in phyllosphere and roots/rhizosphere, the relative abundance of ARGs and MGEs of Gram-negative bacteria, and HGT-rates among Gram-negative bacteria.SP 5 contributes the same expertise and techniques to the joint field experiment with Phaeozem soil irrigated with untreated wastewater for >80 years and planted with cilantro in order to bridge controlled laboratory and greenhouse experiments to real world conditions, especially regarding the effects of irrigation water quality on phyllosphere bacteria, which are difficult to study under greenhouse conditions (reduced radiation and dust inputs).By linking its results and expertise to the data and knowledge of the other SPs of the RU also by means of the integrated mathematical model (SP 7), SP 5 contributes to a mechanistic understanding of interactions between pollutants, antibiotic resistance and pathogens in changing wastewater irrigation systems.