Department of Soil Chemistry, Plant Nutrition and Microbiology, Institute of Soil, Water and Environmental Sciences, The Volcani Center, Agricultural Research Organization, Rishon LeZion 7505101, Israel.
Department of Agroecology and Plant Health, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel.
Environ Sci Technol. 2021 May 18;55(10):6814-6827. doi: 10.1021/acs.est.1c00612. Epub 2021 Apr 27.
Treated-wastewater (TW) irrigation transfers antibiotic-resistant bacteria (ARB) to soil, but persistence of these bacteria is generally low due to resilience of the soil microbiome. Nonetheless, wastewater-derived bacteria and associated antibiotic resistance genes (ARGs) may persist below detection levels and potentially proliferate under copiotrophic conditions. To test this hypothesis, we exposed soils from microcosm, lysimeter, and field experiments to short-term enrichment in copiotroph-stimulating media. In microcosms, enrichment stimulated growth of multidrug-resistant up to 2 weeks after falling below detection limits. Lysimeter and orchard soils irrigated in-tandem with either freshwater or TW were subjected to culture-based, qPCR and shotgun metagenomic analyses prior, and subsequent, to enrichment. Although native TW- and freshwater-irrigated soil microbiomes and resistomes were similar to each other, enrichment resulted in higher abundances of cephalosporin- and carbapenem-resistant and in substantial differences in the composition of microbial communities and ARGs. Enrichment stimulated ARG-harboring Bacillaceae in the freshwater-irrigated soils, whereas in TWW-irrigated soils, ARG-harboring γ-proteobacterial families and were more profuse. We demonstrate that TW-derived ARB and associated ARGs can persist at below detection levels in irrigated soils and believe that similar short-term enrichment strategies can be applied for environmental antimicrobial risk assessment in the future.
经处理的废水（TW）灌溉将抗生素耐药细菌（ARB）转移到土壤中，但由于土壤微生物组的弹性，这些细菌的持久性通常较低。尽管如此，废水衍生的细菌和相关的抗生素抗性基因（ARGs）可能在检测水平以下持续存在，并在富营养条件下潜在增殖。为了验证这一假设，我们将来自微宇宙、淋溶池和田间实验的土壤暴露于短期富营养刺激培养基中。在微宇宙中，在低于检测限后，富集刺激了多药耐药菌的生长长达 2 周。与淡水或 TW 一起灌溉的淋溶池和果园土壤在进行富营养化之前和之后进行了基于培养、qPCR 和鸟枪法宏基因组分析。尽管原生 TW 和淡水灌溉土壤微生物组和抗性组彼此相似，但富集导致头孢菌素和碳青霉烯类耐药菌的丰度增加，并且微生物群落和 ARG 的组成有很大差异。富营养化刺激了淡水灌溉土壤中头孢菌素抗性的芽孢杆菌科，而在 TWW 灌溉土壤中，ARG 携带的γ变形菌科和 更为丰富。我们证明，TW 衍生的 ARB 和相关的 ARGs 可以在灌溉土壤中以低于检测水平的水平持续存在，并且相信未来可以应用类似的短期富集策略进行环境抗菌风险评估。
