摘要

       粪肥和化肥的施用可以显着调节土壤中的细菌群落，但对土壤抗生素抗性的影响及其潜在机制尚不清楚。在本研究中，抗生素抗性基因 (ARG) 和细菌群落分别使用高通量定量 PCR 和 Illumina HiSeq 测序在长期（25 年）田间试验的土壤中进行表征。处理包括不施化肥（对照）、化肥（NPK）、秸秆还田NPK（NPKS）、猪粪（M）和施化肥（NPKM）。 NPK 和 NPKS 都降低了土壤 pH 值并导致细菌群落发生实质性变化，但对 ARG 多样性和丰度只有中等影响。 NPK的主导影响阻碍了秸秆还田的效果。相比之下，添加猪粪（M 和 NPKM）保持了细菌群落的多样性，并通过从猪粪中引入额外的 ARG 和促进土壤土著 ARG 成员显着影响 ARG 谱。施肥土壤含有 ARGs 和转座酶基因簇，它们相对独立于细菌系统发育谱系，表明 ARGs 在土壤细菌中强烈共存，这可能是由水平基因转移 (HGT) 引起的。我们的结果表明 HGT 在维持农业土壤中 ARG 组成方面的重要性，尤其是那些接受长期施肥的土壤。

       Applications of manure and chemical fertilizers can significantly modulate the bacterial communities in soil, but the effects on the soil antibiotic resistome and the underlying mechanisms remain largely unclear. In the present study, antibiotic resistance genes (ARGs) and bacterial communities were characterized using high-throughput quantitative PCR and Illumina HiSeq sequencing, respectively, in soils from a long-term (25 years) field experiment. Treatments included no fertilizers (control), chemical fertilizers (NPK), NPK with straw return (NPKS), pig manure (M), and M with chemical fertilizers (NPKM). Both NPK and NPKS decreased soil pH and induced a substantial shift in the bacterial communities, but had only moderate effect on the ARG diversity and abundance. The effect of straw return was hindered by the dominant influence of NPK. In comparison, additions of pig manure (M and NPKM) maintained the diversity of bacterial community and significantly influenced the ARG profiles by introducing extra ARGs from pig manure and boosting the soil indigenous ARG members. Manured soils harboured clusters of ARGs and transposase genes which were relatively independent of bacterial phylogenetic lineages, suggesting a strong co-occurrence of ARGs in soil bacteria which may result from horizontal gene transfers (HGT). Our results indicate the importance of HGT in the maintenance of ARG composition in agricultural soils, especially those receiving long-term manure applications.

https://www.sciencedirect.com/science/article/abs/pii/S0038071718301299