Jauregi Leire, Epelde Lur, Alkorta Itziar, Garbisu Carlos
Department of Conservation of Natural Resources, NEIKER - Basque Institute for Agricultural Research and Development, Basque Research and Technology Alliance (BRTA), Derio, Spain.
Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), Bilbao, Spain.
Front Vet Sci. 2021 Feb 23;8:633858. doi: 10.3389/fvets.2021.633858. eCollection 2021.
The application of organic amendments to agricultural soil can enhance crop yield, while improving the physicochemical and biological properties of the recipient soils. However, the use of manure-derived amendments as fertilizers entails environmental risks, such as the contamination of soil and crops with antibiotic residues, antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). In order to delve into these risks, we applied dairy cow manure-derived amendments (slurry, fresh manure, aged manure), obtained from a conventional and an organic farm, to soil. Subsequently, lettuce and wheat plants were grown in the amended soils. After harvest, the abundance of 95 ARGs and MGE-genes from the amended soils and plants were determined by high-throughput qPCR. The structure of soil prokaryotic communities was determined by 16S rRNA amplicon sequencing and qPCR. The absolute abundance of ARGs and MGE-genes differed between treatments (amended vs. unamended), origins of amendment (conventional vs. organic), and types of amendment (slurry vs. fresh manure vs. aged manure). Regarding ARG-absolute abundances in the amendments themselves, higher values were usually found in slurry vs. fresh or aged manure. These abundances were generally higher in soil than in plant samples, and higher in wheat grain than in lettuce plants. Lettuce plants fertilized with conventional amendments showed higher absolute abundances of tetracycline resistance genes, compared to those amended with organic amendments. No single treatment could be identified as the best or worst treatment regarding the risk of antibiotic resistance in soil and plant samples. Within the same treatment, the resistome risk differed between the amendment, the amended soil and, finally, the crop. In other words, according to our data, the resistome risk in manure-amended crops cannot be directly inferred from the analysis of the amendments themselves. We concluded that, depending on the specific question under study, the analysis of the resistome risk should specifically focus on the amendment, the amended soil or the crop.
向农业土壤中施用有机改良剂可以提高作物产量，同时改善受体土壤的物理化学和生物学性质。然而，使用源自粪肥的改良剂作为肥料存在环境风险，例如土壤和作物被抗生素残留、抗生素抗性基因（ARGs）和可移动遗传元件（MGEs）污染。为了深入研究这些风险，我们将从传统农场和有机农场获得的奶牛粪肥衍生改良剂（粪水、鲜粪、陈粪）施用于土壤。随后，在改良后的土壤中种植生菜和小麦植株。收获后，通过高通量定量PCR测定改良土壤和植株中95种ARGs和MGE基因的丰度。通过16S rRNA扩增子测序和定量PCR确定土壤原核生物群落的结构。ARGs和MGE基因的绝对丰度在不同处理（改良与未改良）、改良剂来源（传统与有机）以及改良剂类型（粪水与鲜粪与陈粪）之间存在差异。关于改良剂本身的ARG绝对丰度，通常在粪水中的值高于鲜粪或陈粪。这些丰度在土壤中一般高于植物样品，在小麦籽粒中高于生菜植株。与施用有机改良剂的生菜植株相比，施用传统改良剂的生菜植株中四环素抗性基因的绝对丰度更高。在土壤和植物样品的抗生素抗性风险方面，并不能确定哪种单一处理是最佳或最差处理。在相同处理中，抗性组风险在改良剂、改良土壤以及最终的作物之间存在差异。换句话说，根据我们的数据，不能直接从改良剂本身的分析推断出粪肥改良作物中的抗性组风险。我们得出结论，根据所研究的具体问题，抗性组风险分析应具体关注改良剂、改良土壤或作物。
