Data_Sheet_2_Microbial Community Diversity Within Sediments from Two Geographically Separated Hadal Trenches.xls

Hadal ocean sediments, found at sites deeper than 6,000 m water depth, are thought to contain microbial communities distinct from those at shallower depths due to high hydrostatic pressures and higher abundances of organic matter. These communities may also differ from one other as a result of geographical isolation. Here we compare microbial community composition in surficial sediments of two hadal environments—the Mariana and Kermadec trenches—to evaluate microbial biogeography at hadal depths. Sediment microbial consortia were distinct between trenches, with higher relative sequence abundances of taxa previously correlated with organic matter degradation present in the Kermadec Trench. In contrast, the Mariana Trench, and deeper sediments in both trenches, were enriched in taxa predicted to break down recalcitrant material and contained other uncharacterized lineages. At the 97% similarity level, sequence-abundant taxa were not trench-specific and were related to those found in other hadal and abyssal habitats, indicating potential connectivity between geographically isolated sediments. Despite the diversity of microorganisms identified using culture-independent techniques, most isolates obtained under in situ pressures were related to previously identified piezophiles. Members related to these same taxa also became dominant community members when native sediments were incubated under static, long-term, unamended high-pressure conditions. Our results support the hypothesis that there is connectivity between sediment microbial populations inhabiting the Mariana and Kermadec trenches while showing that both whole communities and specific microbial lineages vary between trench of collection and sediment horizon depth. This in situ biodiversity is largely missed when incubating samples within pressure vessels and highlights the need for revised protocols for high-pressure incubations.

在深度超过6,000米水深的海洋深渊沉积物中发现的哈达尔海洋沉积物，因其承受极高的水压和有机物质的高丰度，被认为含有与浅层沉积物中微生物群不同的独特微生物群落。这些群落也可能因地理隔离而彼此不同。在本研究中，我们对比了两个哈达尔环境——马里亚纳和克马德克海沟——表层沉积物中的微生物群落组成，以评估哈达尔深度的微生物生物地理学。海沟之间的沉积物微生物共生体具有显著差异，克马德克海沟中存在与有机物质降解相关的物种的相对序列丰度更高。相比之下，马里亚纳海沟以及两个海沟的更深层沉积物富含能够分解抗逆物质的物种，并包含其他未被表征的谱系。在97%相似度水平上，序列丰富的物种并非海沟特有，与在其他哈达尔和深渊生境中发现的物种相关，表明地理隔离的沉积物之间可能存在联系。尽管使用非培养依赖性技术鉴定出了多种微生物，但在现场压力下获得的多数分离株与先前已知的压力爱好者相关。当在静态、长期、未经修改的高压条件下培养原位沉积物时，与这些相同物种相关的成员也成为了优势群落成员。我们的结果支持了马里亚纳和克马德克海沟中栖息的沉积物微生物种群之间存在联系的假设，同时表明整个群落和特定的微生物谱系在海沟采集点和沉积层深度之间存在差异。在压力容器内培养样品时，这种原位生物多样性在很大程度上被忽视，突显了修订高压培养方案的需求。