摘要

       监测跨生态位的抗生素抗性基因 (ARG) 对于评估不同微生物群落对全球耐药性传播的影响至关重要。在与永久冻土相关的土壤中，气候和人类驱动的干扰增加了近地表解冻，改变了上覆活动层土壤中形成抵抗组的主要细菌。这种解冻在阿拉斯加令人担忧，因为 85% 的土地位于永久冻土之下，这使得土壤特别容易受到干扰。本研究的目的是评估土壤扰动以及随后群落组成的变化将如何影响组成活性层抗性组的 ARG 的类型、丰度和流动性。我们通过以下目标来实现这一目标：(1) 通过抗生素敏感性测试评估耐药表型，以及 (2) 通过对从阿拉斯加内陆干扰诱导的解冻梯度中分离的细菌进行全基因组分析来分析 ARG 的类型、丰度和流动性.我们发现高比例的分离株至少对氨苄青霉素耐药率最高的一种抗生素具有耐药性。 ARGs的丰度和耐药菌株的比例随干扰增加；然而，每个分离株的 ARG 数量更多地由系统发育而不是分离位点来解释。与全球土壤细菌数据库 RefSoil+ 相比，我们来自同一属的分离株具有不同的 ARG，质粒上的比例更高。这些结果强调了系统发育和生态都塑造了抵抗组的假设，并表明由于干扰引起的解冻导致群落组成的变化将反映在构成活性层抵抗组的主要 ARG 中。

       Monitoring antibiotic resistance genes (ARGs) across ecological niches is critical for assessing the impacts distinct microbial communities have on the global spread of resistance. In permafrost-associated soils, climate and human driven disturbances augment near-surface thaw shifting the predominant bacteria that shape the resistome in overlying active layer soils. This thaw is of concern in Alaska, because 85% of land is underlain by permafrost, making soils especially vulnerable to disturbances. The goal of this study is to assess how soil disturbance, and the subsequent shift in community composition, will affect the types, abundance, and mobility of ARGs that compose the active layer resistome. We address this goal through the following aims: (1) assess resistance phenotypes through antibiotic susceptibility testing, and (2) analyze types, abundance, and mobility of ARGs through whole genome analyses of bacteria isolated from a disturbance-induced thaw gradient in Interior Alaska. We found a high proportion of isolates resistant to at least one of the antibiotics tested with the highest prevalence of resistance to ampicillin. The abundance of ARGs and proportion of resistant isolates increased with disturbance; however, the number of ARGs per isolate was explained more by phylogeny than isolation site. When compared to a global database of soil bacteria, RefSoil+, our isolates from the same genera had distinct ARGs with a higher proportion on plasmids. These results emphasize the hypothesis that both phylogeny and ecology shape the resistome and suggest that a shift in community composition as a result of disturbance-induced thaw will be reflected in the predominant ARGs comprising the active layer resistome. 

https://www.mdpi.com/2076-2607/9/1/116