摘要

       本研究对苏格兰草地反复施用不同有机肥的抗药性基因（ARGs）的环境命运进行了评估。以无机肥（NPK）为对照，研究了肥料、生物固体和城市食品堆肥对土壤中四环素ARGs（tetA、tetB、tetC、tetG和tetW）、磺胺ARGs（sul1和sul2）和1类整合子整合酶基因（IntI1）相对丰度的影响。有低强度耕作历史的背景土壤中tet-ARGs的总相对丰度高于sul-ARGs，四环素外排基因的出现频率较高。在所有处理中，土壤中大多数ARGs的相对丰度随着时间的推移而降低，尤其是IntI1和tet ARGs。土壤ARGs的这种普遍衰减反映了土壤微生物群落的变化，实验结束时几乎所有土壤都有不同于实验开始时未处理土壤的细菌群落。有机肥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，使土壤ARGs相对丰度比NPK高，表现为IntI1和tet-ARGs下降幅度较小或sul-ARGs增加。有机肥对土壤中ARGs含量的影响很大程度上取决于有机肥的种类和ARGs的特殊性。堆肥中内源ARGs相对丰度最低，施用后对土壤ARG降低的影响最小。由生物固体引起的tet-ARGs相对增加量大于sul-ARGs，而肥料则相反。施肥对土壤细菌群落的影响不明显，但对ARG库的剖面有显著影响。因此，有机施肥可能主要通过水平基因转移（HGT）加速ARGs在土壤中的传播，这与IntI1在有机施肥土壤中的富集相一致。

        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.

        https://www.sciencedirect.com/science/article/abs/pii/S0147651318311965?via%3Dihub