This study provided an assessment of the environmental fate of antibiotic resistance genes (ARGs) in a Scottish grassland field repeatedly treated with different organic fertilizers. The impacts of manure, biosolids and municipal food-derived compost on the relative abundances of tetracycline ARGs (tetA, tetB, tetC, tetG and tetW), sulfonamide ARGs (sul1 and sul2) and class 1 integron-integrase gene (IntI1) in soils were investigated, with inorganic fertilizer (NPK) as a comparison. The background soil with a history of low intensity farming showed a higher total relative abundance of tet ARGs over sul ARGs, with tetracycline efflux genes occurring in a higher frequency. In all treatments, the relative abundances of most ARGs detected in soils decreased over time, especially IntI1 and tet ARGs. This general attenuation of soil ARGs is a reflection of changes in the soil microbial community, which is supported by the result that almost all the soils at the end of the experiment had different bacterial communities from the untreated soil at the beginning of the experiment. Multiple applications of organic fertilizers to some extent counteracted the decreasing trend of soil ARGs relative abundances, which resulted in higher ARGs relative abundances in comparison to NPK, either by a lesser decrease of IntI1 and tet ARGs or an increase of sul ARGs. The enhancement of existing soil ARG prevalence by organic fertilizers was strongly dependent on the organic fertilizer type and the particular ARG. Compost contained the lowest relative abundance of inherent ARGs and had the least effect on the soil ARG decrease after application. The relative increase of tet ARGs caused by biosolids was larger than that of sul ARGs, while manure caused the opposite effect. Fertilization practices did not exert effective impacts on the soil bacterial community, although it caused significant changes in the profile of the ARG pool. Organic fertilization may thus accelerate the dissemination of ARGs in soil mainly through horizontal gene transfer (HGT), consistent with the enrichment of IntI1 in organic fertilized soils.

这项研究提供了在苏格兰草原上反复使用不同有机肥料处理过的抗生素抗性基因（ARG）的环境命运的评估。粪肥，生物固体和市政食物堆肥对土壤中四环素ARGs（tetA，tetB，tetC，tetG和tetW），磺酰胺类ARGs（sul1和sul2）和1类整合素整合酶基因（IntI1）相对丰度的影响进行了调查，并与无机肥料（NPK）作了比较。具有低强度耕作历史的背景土壤显示，tet ARGs的总相对丰度较高sul ARGs，四环素外排基因发生频率更高。在所有处理中，土壤中检测到的大多数ARGs的相对丰度都随时间降低，尤其是IntI1和tet ARGs。土壤ARGs的这种一般衰减反映了土壤微生物群落的变化，这得到了以下结果的支持：实验结束时，几乎所有土壤与实验开始时未经处理的土壤均具有不同的细菌群落。有机肥料的多次施用在一定程度上抵消了土壤ARGs相对丰度的下降趋势，与NPK相比，导致ARGs相对丰度更高，原因是IntI1和tet的减少较小ARG或sul ARG的增加。有机肥料对现有土壤ARG流行的增强在很大程度上取决于有机肥料的类型和特定的ARG。堆肥中固有ARG的相对丰度最低，对施用后土壤ARG降低的影响最小。生物固形物引起的tet ARGs的相对增加量大于sul ARG的相对增加，而粪肥则产生相反的作用。施肥措施虽然对ARG库的轮廓造成了重大变化，但并未对土壤细菌群落产生有效影响。因此，有机肥可能主要通过水平基因转移（HGT）促进ARG在土壤中的传播，这与土壤肥料的富集相一致。有机肥土壤中的IntI1。