Data_Sheet_1_Microbial Community Diversity Within Sediments from Two Geographically Separated Hadal Trenches.docx

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.

位于水深超过6,000米的深海沉积物中的Hadal海洋沉积物，因其所承受的高静水压力和有机物含量丰富，被认为含有与浅层沉积物中微生物群落不同的微生物群落。这些群落由于地理隔离也可能彼此不同。在本研究中，我们比较了马里亚纳和克马德克海沟两个Hadal环境表层沉积物中的微生物群落组成，以评估深海微生物的生态地理分布。海沟间的沉积物微生物群落存在差异，克马德克海沟中存在与有机物降解相关的类群的高相对序列丰度。相比之下，马里亚纳海沟及其两个海沟中的深层沉积物富含可降解抗逆材料的类群以及其他未鉴定的谱系。在97%相似度水平上，序列丰富的类群并非海沟特异性，与在其他深海和深渊生境中发现的类群相关，表明地理隔离的沉积物之间可能存在连通性。尽管使用无培养依赖技术鉴定了微生物的多样性，但在原位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、未修改的高压条件下培养原位沉积物时，与这些相同类群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的沉积物微生物种群之间存在连通性的假设，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物层深度之间存在差异。在压力容器中培养样本时，这种原位生物多样性往往被忽视，这突显了需要修订高压培养的方案。