摘要

   长期的牲畜放牧通常伴随着动物粪便和尿液进入草原土壤，并会影响微生物群落。然而，放牧对土壤抗生素抗性基因（ARGs）多样性和丰度的影响仍不清楚。在这里，我们使用高通量定量 PCR 分析内蒙古沙漠和典型草原（分别为四子王和锡林郭勒草原）的土壤抗性组，每个草原都有四种放牧强度（无放牧、轻度放牧、中度放牧和重度放牧）。在四子王草原和锡林郭勒草原分别检测到54个和39个ARGs。四子王草原的ARGs相对丰度随着放牧强度的增加而显着降低或在锡林郭勒草原保持不变。移动遗传元件（MGEs）与四子王草原的ARGs呈显着正相关，而在锡林郭勒草原则没有。结构方程模型显示，放牧通过对 MGE、细菌多样性和细菌群落组成的影响间接影响 ARG。这些发现表明，牲畜放牧可以通过调节草原土壤中的微生物群来影响土壤抵抗力。然而，放牧强度并未对这些沙漠和典型草原的土壤抗性产生显着影响

  Long-term livestock grazing often comes with inputs of manure and urine of animals to grassland soils and can influence the microbial communities. However, the effects of grazing on the diversity and abundance of soil antibiotic resistance genes (ARGs) are still obscure. Here we profiled soil resistome using high-throughput quantitative PCR analysis from desert and typical grasslands (Siziwang and Xilingol steppe, respectively) in Inner Mongolia, each with four grazing intensities (no grazing, light grazing, moderate grazing, and heavy grazing). Totally, 54 and 39 ARGs were detected in the Siziwang steppe and the Xilingol steppe, respectively. The relative abundance of ARGs significantly decreased in the Siziwang steppe or remained unchanged in the Xilingol steppe along the gradient of increasing grazing intensity. Mobile genetic elements (MGEs) were significantly and positively correlated with ARGs in the Siziwang steppe but not in the Xilingol steppe. Structural equation model revealed that grazing indirectly affected ARGs through its impact on MGEs, bacterial diversity, and bacterial community composition. These findings suggest that livestock grazing can impact soil resistome via regulating microbiome in grassland soils. However, grazing intensity has not resulted in a significant impact on the soil resistomes in these desert and typical grasslands.

  https://www.sciencedirect.com/science/article/abs/pii/S0929139319312521