Haan Tracie J, Drown Devin M
Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
Microorganisms. 2021 Jan 6;9(1):116. doi: 10.3390/microorganisms9010116.
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.
监测不同生态位中的抗生素抗性基因（ARGs）对于评估不同微生物群落对耐药性全球传播的影响至关重要。在与永久冻土相关的土壤中，气候和人类活动引起的干扰加剧了近地表解冻，改变了在上覆活动层土壤中形成抗性组的主要细菌。这种解冻在阿拉斯加令人担忧，因为85%的土地下面是永久冻土，使得土壤特别容易受到干扰。本研究的目的是评估土壤干扰以及随后群落组成的变化将如何影响构成活动层抗性组的ARGs的类型、丰度和流动性。我们通过以下目标来实现这一目的：（1）通过抗生素敏感性测试评估抗性表型，以及（2）通过对从阿拉斯加内陆干扰引起的解冻梯度中分离出的细菌进行全基因组分析，分析ARGs的类型、丰度和流动性。我们发现，高比例的分离株对至少一种测试抗生素具有抗性，其中对氨苄青霉素的抗性最为普遍。ARGs的丰度和抗性分离株的比例随干扰而增加；然而，每个分离株的ARGs数量更多地由系统发育而非分离位点来解释。与全球土壤细菌数据库RefSoil+相比，我们同一属的分离株具有不同的ARGs，且质粒上的比例更高。这些结果强调了系统发育和生态学都塑造抗性组的假设，并表明干扰引起的解冻导致的群落组成变化将反映在构成活动层抗性组的主要ARGs中。
