Sediments within the Okinawa back-arc basin overlay a subsurface hydrothermal network, creating intense temperature gradients with sediment depth and potential limits for microbial diversity. We investigated taxonomic changes across 45 m of recovered core with a temperature gradient of 3°C/m from the dynamic Iheya North Hydrothermal System. The interval transitions sharply from low-temperature marine mud to hydrothermally altered clay at 10 meters below seafloor (mbsf). Here, we present taxonomic results from an analysis of the 16S rRNA gene that support a conceptual model in which common marine subsurface taxa persist into the subsurface, while high temperature adapted archaeal taxa show localized peaks in abundances in the hydrothermal clay horizons. Specifically, the bacterial phylum Chloroflexi accounts for a major proportion of the total microbial community within the upper 10 mbsf, whereas high temperature archaea (Terrestrial Hot Spring Crenarchaeotic Group and methanotrophic archaea) appear in varying local abundances in deeper, hydrothermal clay horizons with higher in situ temperatures (up to 55°C, 15 mbsf). In addition, geochemical evidence suggests that methanotrophy may be occurring in various horizons. There is also relict DNA (i.e., DNA preserved after cell death) that persists in horizons where the conditions suitable for microbial communities have ceased.

中文翻译：

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冲绳海槽沉积物中水热梯度下海洋地下微生物群落的变化。

冲绳后弧盆地内的沉积物覆盖了地下热液网络，形成了强烈的温度梯度，沉积物深度和微生物多样性的潜在限制。我们研究了动态Iheya North热液系统在45 m的已回收岩心中的分类学变化，温度梯度为3°C / m。间隔从海底低温泥浆急剧转变为海底（mbsf）下方10米处的水热蚀变粘土。在这里，我们通过对16S rRNA基因的分析提供了分类学结果，该基因支持一个概念模型，在该模型中，常见的海洋地下生物分类群持续存在于地下，而高温适应的古细菌生物分类群在热液粘土层中显示了丰度的局部峰值。具体来说，原位温度（最高55°C，15 mbsf）。此外，地球化学证据表明甲烷异养作用可能发生在各个层面。还有残留的DNA（即细胞死亡后保留的DNA）在适合微生物群落的条件已经消失的地平线上持续存在。