摘要

土壤是抗生素抗性基因（ARGs）的储器，但是ARG的环境动力学在很大程度上是未知的。长期干扰提供机会来检查与生态和进化过程相关的尺度上的微生物群体反应，并且可以对研究ARGs具有洞察力。我们在1962年以来一直燃烧的宾夕法尼亚州Centralia的地下煤层火灾的土壤中检测了ARGs。随着火灾的发展，以前炎热的土壤会恢复到环境温度，从而产生火灾影响。我们沿着这种梯度检测了表层土壤中的宏基因组，以使用基因靶向装配器检测ARG。我们针对35个临床相关ARG和两个水平基因转移相关基因（intI和repA）。我们在Centralia检测到17种ARG：AAC6-Ia，adeB，bla_A，bla_B，bla_C，cmlA，dfra12，intI，sul2，tetA，tetW，tetX，tolC，vanA，vanH，vanX和vanZ。 bla_A，bla_B，dfra12和tolC的多样性和丰富度随着土壤温度而降低，ARGs的变化主要由群落结构的变化所解释。我们沿着温度梯度观察序列特异性生物地理学并且观察到bla_A，dfra12和intI中的组成变化。这些结果表明，气温升高可以减少土壤ARGs，但这主要是由于社区层面多样性的减少。

Soils are reservoirs of antibiotic resistance genes (ARGs), but environmental dynamics of ARGs are largely unknown. Long-term disturbances offer opportunities to examine microbiome responses at scales relevant for both ecological and evolutionary processes and can be insightful for studying ARGs. We examined ARGs in soils overlying the underground coal seam fire in Centralia, PA, which has been burning since 1962. As the fire progresses, previously hot soils can recover to ambient temperatures, which creates a gradient of fire impact. We examined metagenomes from surface soils along this gradient to examine ARGs using a gene-targeted assembler. We targeted 35 clinically relevant ARGs and two horizontal gene transfer-related genes (intIand repA). We detected 17 ARGs in Centralia: AAC6-Ia, adeB, bla_A, bla_B, bla_C,cmlA, dfra12, intI, sul2, tetA, tetW, tetX, tolC, vanA, vanH, vanX and vanZ. The diversity and abundance of bla_A, bla_B, dfra12 and tolC decreased with soil temperature, and changes in ARGs were largely explained by changes in community structure. We observed sequence-specific biogeography along the temperature gradient and observed compositional shifts in bla_A, dfra12 andintI. These results suggest that increased temperatures can reduce soil ARGs but that this is largely due to a concomitant reduction in community-level diversity.

https://academic.oup.com/femsec/article-abstract/94/3/fiy016/4834000