摘要

       抗生素抗性基因 (ARG) 的新环境传播及其随后被临床相关微生物获取是对公共健康的主要威胁。动物粪便被认为是 ARG 的重要储存库；然而，粪便衍生的 ARG 的传播以及粪便施用对土壤抵抗力的影响仍然不清楚。在这里，我们进行了一项微观研究，以评估未用抗生素处理的牛粪施用后两种对比土壤中总细菌和广谱 ARG 的时间序列。高容量定量 PCR 在所有样品中检测到 52 个独特的 ARG，其中 β-内酰胺酶是最主要的 ARG 类型。在粪便中检测不到的土壤原生细菌的几个基因对 β-内酰胺具有抗性，在经过粪便处理的土壤中被发现高度富集，并且在整个过程中保持了 140 天的富集水平。富集的 β-内酰胺抗性基因与整合酶 intI1 基因的相对丰度呈显着正相关，表明在粪肥处理的土壤中流动潜力增加。 ARG 模式的变化伴随着牛粪对总细菌群落组成的显着影响。我们的研究表明，即使在农业使用抗生素没有选择压力的情况下，粪肥施用仍会强烈影响广谱土壤 ARG 的丰度、多样性和流动潜力。我们的发现对于可靠预测土壤环境中的 ARG 行为和制定适当的策略以最大程度地减少其传播非常重要。

       The emerging environmental spread of antibiotic-resistance genes (ARGs) and their subsequent acquisition by clinically relevant microorganisms is a major threat to public health. Animal manure has been recognized as an important reservoir of ARGs; however, the dissemination of manure-derived ARGs and the impacts of manure application on the soil resistome remain obscure. Here, we conducted a microcosm study to assess the temporal succession of total bacteria and a broad spectrum of ARGs in two contrasting soils following manure application from cattle that had not been treated with antibiotics. High-capacity quantitative PCR detected 52 unique ARGs across all the samples, with β-lactamase as the most dominant ARG type. Several genes of soil indigenous bacteria conferring resistance to β-lactam, which could not be detected in manure, were found to be highly enriched in manure-treated soils, and the level of enrichment was maintained over the entire course of 140 days. The enriched β-lactam resistance genes had significantly positive relationships with the relative abundance of the integrase intI1 gene, suggesting an increasing mobility potential in manure-treated soils. The changes in ARG patterns were accompanied by a significant effect of cattle manure on the total bacterial community compositions. Our study indicates that even in the absence of selective pressure imposed by agricultural use of antibiotics, manure application could still strongly impact the abundance, diversity and mobility potential of a broad spectrum of soil ARGs. Our findings are important for reliable prediction of ARG behaviors in soil environment and development of appropriate strategies to minimize their dissemination.

https://academic.oup.com/femsec/article/92/2/fiv169/2484746?login=true