摘要
      施用粪肥增加了抗生素耐药性向农田转移的风险。特别是，当它出现在砷污染的水稻土中时，其影响尚不清楚，这被认为是一个全球环境问题。在这项工作中，我们研究了在施用不同来源的粪肥（猪粪、牛粪和鸡粪）的情况下，抗生素抗性基因（ARGs）在砷-抗生素共同污染的水稻土中的命运。这些溶解有机物（DOM）的脂族碳和给电子能力的差异通过生物和非生物过程调节铁和砷的转化。猪粪的调节作用强于牛粪和鸡粪。DOM调节增加了土壤中As相关功能基因（arsC、arrA、aioA和arsM）的丰度，并加速了As物种的转化，As（III）的最高比例为45%-61%。同时，剧毒As（III）提供的持续选择压力通过水平基因转移增加了ARGs和可移动遗传元件（MGE）的风险。作为抗性细菌，包括芽孢杆菌、地杆菌和脱硫杆菌，最终被认为是ARGs和MGE的潜在宿主细菌。总之，本研究阐明了As抗生素对共污染水稻土中ARGs命运的协同作用机制，并为有机肥料的合理施用提供了实际指导。
Abstract
Manure application increases the transfer risk of antibiotic resistance to farmland. Especially, its impact remains unclear when it occurs in arsenic (As)-contaminated paddy soils, which is considered as a global environmental problem. In this work, we investigated the fate of antibiotic resistance genes (ARGs) in As-antibiotic co-contaminated paddy soils under the application of manure from different sources (pig manure, cow dung, and chicken manure). Differences in the aliphatic carbon and electron-donating capacities of these dissolved organic matters (DOM) regulated the transformation of iron and As by both biotic and abiotic processes. The regulation by pig manure was stronger than that by cow dung and chicken manure. DOM regulation increased the abundance of As-related functional genes (arsC, arrA, aioA, and arsM) in the soil and accelerated the transformation of As speciation, the highest proportion of As(III) being 45%–61%. Meanwhile, the continuous selection pressure provided by the highly toxic As(III) increased the risk of ARGs and mobile genetic elements (MGEs) via horizontal gene transfer. As-resistant bacteria, including Bacillus, Geobacter, and Desulfitobacterium, were finally considered as potential host bacteria for ARGs and MGEs. In summary, this study clarified the synergistic mechanism of As-antibiotic on the fate of ARGs in co-contaminated paddy soils, and provided practical guidance for the proper application of organic fertilizers.

https://www.sciencedirect.com/science/article/abs/pii/S0269749122005905