Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021, China.
University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
Environ Sci Technol. 2021 Jan 5;55(1):423-432. doi: 10.1021/acs.est.0c03893. Epub 2020 Dec 17.
Applying organic fertilizers has been well documented to facilitate the dissemination of antibiotic resistance genes (ARGs) in soil ecosystems. However, the role of soil fauna in this process has been seldom addressed, which hampers our ability to predict the fate of and to manage the spread of ARGs. Here, using high-throughput quantitative polymerase chain reaction (HT-qPCR), we examined the effect of long-term (5-, 8-, and 10-year) fertilization treatments (control, inorganic fertilizers, and mixed fertilizers) on the transfer of ARGs between soil, nematodes, and earthworms. We found distinct fates for ARGs in the nematodes and earthworms, with the former having higher enriched levels of ARGs than the latter. Fertilization impacted the number and abundance of ARGs in soil, and fertilization duration altered the composition of ARGs. Shared ARGs among soil, nematodes, and earthworm guts supported by a fast expectation-maximization microbial source tracking analysis demonstrated the trophic transfer potential of ARGs through this short soil food chain. The transfer of ARGs was reduced by fertilization duration, which was mainly ascribed to the reduction of ARGs in the earthworm gut microbiota. This study identified the transfer of ARGs in the soil-nematode-earthworm food chain as a potential mechanism for a wider dissemination of ARGs in the soil ecosystem.
施用有机肥已被充分证明可促进土壤生态系统中抗生素抗性基因（ARGs）的传播。然而，土壤动物在这一过程中的作用很少被提及，这限制了我们预测 ARGs 命运和管理其传播的能力。在这里，我们使用高通量定量聚合酶链反应（HT-qPCR）研究了长期（5、8 和 10 年）施肥处理（对照、无机肥和混合肥）对土壤、线虫和蚯蚓之间 ARGs 转移的影响。我们发现 ARGs 在线虫和蚯蚓中有不同的归宿，前者比后者具有更高的 ARGs 富集水平。施肥影响了土壤中 ARGs 的数量和丰度，施肥时间改变了 ARGs 的组成。通过快速期望最大化微生物源跟踪分析支持的土壤、线虫和蚯蚓肠道之间的共享 ARGs 表明，ARGs 通过这条短的土壤食物链具有潜在的营养转移能力。ARGs 的转移随着施肥时间的延长而减少，这主要归因于蚯蚓肠道微生物群中 ARGs 的减少。本研究确定了土壤-线虫-蚯蚓食物链中 ARGs 的转移是 ARGs 在土壤生态系统中更广泛传播的潜在机制。
