Manure application to soil affects the composition of soil bacterial communities as well as levels of antibiotic resistance genes in a manner dependent on various environmental and agricultural factors. These effects have been widely studied in arable soils, while the situation in grasslands that also receive inputs of fresh animal manure is largely unknown. Here, we focused on grassland soils under three different management types (pristine meadow, pasture, wintering pasture) from the same locality and compared the response of their bacterial communities to fresh cattle manure spiked or not with chlortetracycline. Soil microcosms were established either with soils (controls), + manure, + manure and chlortetracycline (CTC, 0.2 mg kg⁻¹), and sampled at the same day (t0) and after 28 days (t28). Bacterial community composition was assessed by 454-pyrosequencing of 16S rRNA genes and correlations between the abundance of bacterial taxa and chosen tetracycline resistance genes (measured in our previous study) were calculated. Control soil bacterial communities at t0 differed significantly, reflecting differences in soil management history. Despite these initial differences, the responses of soil bacterial communities to cattle manure amendment showed similar trends in all three soils. Fresh cattle manure amendments significantly modified bacterial community structure in all soils at t0, increasing the relative abundance of OTUs affiliated to Clostridia and Bacilli. At 28d, all manure-amended soils showed a partial resilience, though they remained significantly different from controls. The effect of additional CTC was comparatively lower and only significant at t0 in all three soils. Several members of Firmicutes showed strong positive correlation with the abundance of tetracycline resistance genes tet(O), tet(Q) and tet(W), indicating that these taxa are potentially involved in dissemination of tetracycline resistance in manure-treated soils. In addition, this study indicated certain soil-management specific taxa, such as Geothrix and uncultured Burkholderiaceae, which could explain the previously observed differences in persistence of tetracycline resistance genes among soils.

将肥料施用到土壤中会以各种环境和农业因素为依托，影响土壤细菌群落的组成以及抗生素抗性基因的水平。在可耕作的土壤中已经广泛研究了这些影响，而在很大程度上，还接受新鲜动物粪便投入的草原的情况却鲜为人知。在这里，我们集中研究了来自同一地区的三种不同管理类型（原始草甸，牧场，越冬牧场）下的草地土壤，并比较了它们的细菌群落对添加或未添加金霉素的新鲜牛粪的响应。用土壤（对照），+肥料，+肥料和金霉素（CTC，0.2 mg kg ^-1）建立土壤微观世界），并在同一天（t0）和28天后（t28）进行采样。通过对16S rRNA基因进行454焦磷酸测序来评估细菌群落组成，并计算出细菌类群的丰度与所选四环素抗性基因（在我们先前的研究中测得）之间的相关性。t0时对照土壤细菌群落差异显着，反映了土壤管理历史的差异。尽管存在这些最初的差异，但土壤细菌群落对牛粪改良的响应在所有三种土壤中均显示出相似的趋势。在t0时，新鲜牛粪改良剂显着改变了所有土壤中的细菌群落结构，从而增加了梭状芽胞杆菌和芽孢杆菌属的OTU的相对丰度。在第28天，所有肥料改良后的土壤均显示出部分回弹力，尽管它们仍然与对照组有很大的不同。在所有三种土壤中，额外的四氯化碳的影响相对较低，仅在t0时才显着。Firmicutes的几个成员与四环素抗性基因的丰度显示出强烈的正相关性tet（O），tet（Q）和tet（W），表明这些类群可能与肥料处理过的土壤中四环素抗性的传播有关。此外，这项研究还表明了某些土壤管理的特定分类，例如Geothrix和未培养的Burkholderiaceae，这可以解释先前观察到的土壤中四环素抗性基因持久性的差异。