摘要

土壤是抗生素抗性基因（ARGs）的储藏库，但是ARGs的环境动力学在很大程度上是未知的。长期扰动提供了以与生态和进化过程均相关的尺度检查微生物组反应的机会，并且对于研究ARGs可能很有见地。我们检查了自1962年以来一直在燃烧的宾夕法尼亚州Centralia地下煤层大火上方土壤中的ARG。随着大火的进行，以前很热的土壤可以恢复到环境温度，从而形成了火势梯度。我们检查了沿此梯度从表层土壤中获得的基因组，以使用基因靶向组装器检查了ARGs。我们针对35个临床相关的ARG和两个水平基因转移相关基因（intI和repA）。我们在中部地区检测到17个ARG：AAC6-Ia，adeB，bla_A，bla_B，bla_C，cmlA，dfra12，int1，sul2，tetA，tetW，tetX，tolC，vanA，vanH，vanX和vanZ。 bla_A，bla_B，dfra12和tolC的多样性和丰度随着土壤温度的降低而降低，并且ARGs的变化很大程度上由群落结构的变化解释。我们观察到沿温度梯度的序列特异性生物地理学，并观察到bla_A，dfra12和intI的成分变化。这些结果表明，升高温度可以减少土壤ARGs，但这主要是由于社区一级的多样性随之减少。

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 (intI and 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 and intI. 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/94/3/fiy016/4834000