摘要

       回收到作物生产土地上的动物粪便和城市生物固体携带抗生素抗性细菌，这些细菌会影响农业土壤的抗生素抗性，但在这种情况下，关于噬菌体对抗生素抗性基因 (ARG) 传播的贡献知之甚少。在这项工作中，我们通过定量 PCR 对农业土壤的细菌和噬菌体部分中的一组 ARG 进行了量化。所有测试的 ARG 均存在于细菌和噬菌体部分中。我们证明，用牛粪或人类生物固体施肥土壤会增加细菌部分中的 ARG 丰度，但不会增加细菌部分中的 ARG 丰度，并进一步表明，对牛粪进行预处理会影响细菌部分中的 ARG 丰度。最后，我们表明纯化的噬菌体在与选择压力相结合时可以增强对土壤细菌的抗生素抗性。结果表明，土传噬菌体代表了一个重要的抗生素抗性库，噬菌体可以在农业土壤微生物群落中抗性基因的水平转移中发挥重要作用。总体而言，我们的工作加强了在田间应用前堆肥或消化粪便材料的可取性，并表明以亚临床浓度应用一些抗生素可以促进噬菌体介导的 ARG 在农业土壤微生物群中的水平转移。

       Animal manures and municipal biosolids recycled onto crop production land carry antibiotic-resistant bacteria that can influence the antibiotic resistome of agricultural soils, but little is known about the contribution of bacteriophage to the dissemination of antibiotic resistance genes (ARGs) in this context. In this work, we quantified a set of ARGs in the bacterial and bacteriophage fractions of agricultural soil by quantitative PCR. All tested ARGs were present in both the bacterial and phage fractions. We demonstrate that fertilization of soil with dairy manure or human biosolids increases ARG abundance in the bacterial fraction but not the bacteriophage fraction and further show that pretreatment of dairy manure can impact ARG abundance in the bacterial fraction. Finally, we show that purified bacteriophage can confer increased antibiotic resistance to soil bacteria when combined with selective pressure. The results indicate that soilborne bacteriophage represents a substantial reservoir of antibiotic resistance and that bacteriophage could play a significant role in the horizontal transfer of resistance genes in the context of an agricultural soil microbiome. Overall, our work reinforces the advisability of composting or digesting fecal material prior to field application and suggests that application of some antibiotics at subclinical concentrations can promote bacteriophage-mediated horizontal transfer of ARGs in agricultural soil microbiomes.

https://journals.asm.org/doi/full/10.1128/AEM.02363-15