摘要

       土壤是抗生素抗性基因 (ARG) 的储存库，但 ARG 的环境动态在很大程度上是未知的。长期干扰提供了在与生态和进化过程相关的尺度上检查微生物组反应的机会，并且可以对研究 ARG 有见地。我们检查了宾夕法尼亚州 Centralia 地下煤层火灾覆盖的土壤中的 ARG，该火灾自 1962 年以来一直在燃烧。随着火灾的发展，之前炎热的土壤可以恢复到环境温度，这会产生火灾影响的梯度。我们沿着这个梯度检查了来自表层土壤的宏基因组，以使用基因靶向组装器检查 ARG。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 Centralia 中检测到 17 个 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 的多样性和丰度随着土壤温度的升高而降低，ARGs 的变化主要由群落结构的变化来解释。我们沿温度梯度观察到序列特异性生物地理学，并观察到 bla_A、dfra12 和 intI 的组成变化。这些结果表明，温度升高可以减少土壤 ARG，但这主要是由于社区水平多样性随之减少。

       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?login=true