Climate oscillations reflected within the microbiome of Arabian Sea sediments
Climate oscillations reflected within the microbiome of Arabian Sea sediments
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DOI：
10.1038/s41598-017-05590-9
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发表时间：
2017-07-20
影响因子：
4.6
通讯作者：
Giosan, Liviu
中科院分区：
文献类型：
--
作者：
Orsi, William D.;Coolen, Marco J. L.;Giosan, Liviu
海洋沉积物中微生物的选择是由产生能量的呼吸电子受体决定的，这些电子受体在垂直顺序中耗尽。然而，据报道，一些分类群反映了过去的沉积条件，表明它们在埋葬后经历了弱选择。在阿拉伯海氧气最小带(OMZ)之下的沉积物中，我们在多代理古气候重建的背景下，首次进行了百年尺度下沉积DNA的元基因组学描述。尽管硫酸盐还原细菌和产甲烷菌的垂直分布表明了缺氧海洋沉积物典型的基于能量的选择，但每个样本中有5%-15%的分类群具有与深度无关的地层学，表明在相对较短的地质时间尺度上进行了古环境选择。尽管是垂直分离的，但在OMZ条件下沉积的指示类群彼此之间更相似，而不是在高氧干扰下沉积在生物扰动间隔中的指示类群。基因组的反硝化潜力也与古OMZ代用品相关，与沉积物深度和有效硝酸盐和亚硝酸盐无关。然而，元基因组揭示了由许多相同的反硝化物组编码的混合酸和Entner-Dourdoroff发酵途径。因此，发酵可以解释这些兼性厌氧微生物的生存，它们的地层随着古海洋条件的变化而变化。至少对于某些分类群，我们的分析提供了它们在上一次冰川-间冰期周期中的古环境选择的证据。
Selection of microorganisms in marine sediment is shaped by energy-yielding electron acceptors for respiration that are depleted in vertical succession. However, some taxa have been reported to reflect past depositional conditions suggesting they have experienced weak selection after burial. In sediments underlying the Arabian Sea oxygen minimum zone (OMZ), we performed the first metagenomic profiling of sedimentary DNA at centennial-scale resolution in the context of a multi-proxy paleoclimate reconstruction. While vertical distributions of sulfate reducing bacteria and methanogens indicate energy-based selection typical of anoxic marine sediments, 5-15% of taxa per sample exhibit depth-independent stratigraphies indicative of paleoenvironmental selection over relatively short geological timescales. Despite being vertically separated, indicator taxa deposited under OMZ conditions were more similar to one another than those deposited in bioturbated intervals under intervening higher oxygen. The genomic potential for denitrification also correlated with palaeo-OMZ proxies, independent of sediment depth and available nitrate and nitrite. However, metagenomes revealed mixed acid and Entner-Dourdoroff fermentation pathways encoded by many of the same denitrifier groups. Fermentation thus may explain the subsistence of these facultatively anaerobic microbes whose stratigraphy follows changing paleoceanographic conditions. At least for certain taxa, our analysis provides evidence of their paleoenvironmental selection over the last glacial-interglacial cycle.