Institute of International Rivers and Eco-security, Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming, 650500, China; State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
Institute of International Rivers and Eco-security, Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming, 650500, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
J Environ Manage. 2023 Sep 15;342:118037. doi: 10.1016/j.jenvman.2023.118037. Epub 2023 May 11.
Revealing the effects of reforestation on soil antibiotic resistome is essential for assessing ecosystem health, yet related studies remain scarce. Here, to determine the responses of the soil antibiotic resistome to reforestation, 30 pairs of cropland and forest soil samples were collected from southwestern China, a region with high environmental heterogeneity. All the forests had been derived from croplands more than one decade ago. The diversity and abundance of soil antibiotic resistance genes (ARGs), metal resistance genes (MRGs), mobile genetic elements (MGEs), and pathogens were determined by metagenomic sequencing and real-time PCR. The results showed that reforestation significantly increased soil microbial abundance and the contents of Cu, total carbon, total nitrogen, total organic carbon, and ammonium nitrogen. Nevertheless, it decreased the contents of soil Zn, Ba, nitrate nitrogen, and available phosphorus. The main soil ARGs identified in this region were vancomycin, multidrug, and bacitracin resistance genes. Reforestation significantly increased the soil ARG abundance by 62.58%, while it decreased the ARG richness by 16.50%. Reforestation exerted no significant effects on the abundance of heavy metal resistance genes and pathogens, but it doubled the abundance of MGEs. Additionally, reforestation substantially decreased the co-occurrence frequencies of ARGs with MRGs and pathogens. In contrast, the correlation between ARGs and MGEs was greatly enhanced by reforestation. Similarly, the correlations between soil ARG abundance and environmental factors were also strengthened by reforestation. These findings suggest that reforestation can substantially affect the soil antibiotic resistome and exerts overall positive effects on soil health by decreasing ARG richness, providing critical information for assessing the effects of "grain for green" project on soil health.
揭示造林对土壤抗生素抗性组的影响对于评估生态系统健康至关重要，但相关研究仍然很少。在这里，为了确定土壤抗生素抗性组对造林的响应，我们从中国西南部（一个环境异质性很高的地区）收集了 30 对农田和森林土壤样本，这些森林都是在十多年前从农田衍生而来的。通过宏基因组测序和实时 PCR 测定了土壤抗生素抗性基因 (ARGs)、金属抗性基因 (MRGs)、移动遗传元件 (MGEs) 和病原体的多样性和丰度。结果表明，造林显著增加了土壤微生物丰度和 Cu、总碳、总氮、总有机碳和铵态氮的含量。然而，它降低了土壤 Zn、Ba、硝酸盐氮和有效磷的含量。该地区主要的土壤 ARGs 是万古霉素、多药和杆菌肽抗性基因。造林使土壤 ARG 丰度增加了 62.58%，而 ARG 丰富度减少了 16.50%。造林对重金属抗性基因和病原体的丰度没有显著影响，但使 MGEs 的丰度增加了一倍。此外，造林显著降低了 ARGs 与 MRGs 和病原体的共现频率。相比之下，造林大大增强了 ARGs 与 MGEs 之间的相关性。同样，造林也增强了土壤 ARG 丰度与环境因素之间的相关性。这些发现表明，造林可以显著影响土壤抗生素抗性组，并通过降低 ARG 丰富度对土壤健康产生整体积极影响，为评估“退耕还林”工程对土壤健康的影响提供了关键信息。
