Microbial Abundance and Diversity in Subsurface Lower Oceanic Crust at Atlantis Bank, Southwest Indian Ridge
Microbial Abundance and Diversity in Subsurface Lower Oceanic Crust at Atlantis Bank, Southwest Indian Ridge
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DOI：
10.1128/aem.01519-21
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发表时间：
2021-09
影响因子：
4.4
通讯作者：
S. Y. Wee;V. Edgcomb;D. Beaudoin;S. Yvon-Lewis;J. Sylvan
中科院分区：
文献类型：
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作者：
S. Y. Wee;V. Edgcomb;D. Beaudoin;S. Yvon-Lewis;J. Sylvan
海底以下的下层洋壳是地球上开发最少的栖息地之一。来自西南印度洋海脊(SWIR)的岩石与其他海洋行星和卫星上的岩石环境相似。摘要国际海洋发现计划360在亚特兰蒂斯浅滩钻探了U1473A孔，这是一个位于西南印度洋海脊的海洋核心综合体，目的是恢复具有代表性的下洋壳样品。回收的岩心主要是辉长岩和橄榄辉长岩。这些矿物学可能包含蛇纹岩作用，这些反应有可能在恢复的岩石内或亚特兰蒂斯浅滩下更深的地方支持微生物生命。我们对从U1473A孔获得的岩石样品进行了原核细胞量化和微生物群落组成分析，并进行了营养添加实验，以评估养分供应是否影响微生物群落的组成。微生物丰度较低(≤~(10~4)Cells cm−~3)，但在一定深度范围内与岩石中矿脉的存在呈正相关。由于井下岩石的非均质性(相对未改变的辉长岩和更显著的蚀变和破碎岩石的交替延伸)，当考虑到所有深度时，岩石特征与微生物丰度之间的正相关性的强度较弱。微生物群落多样性在所分析的每个深度都有所不同。令人惊讶的是，在营养添加实验中添加简单的有机酸、铵、磷酸盐或铵+磷酸盐并没有影响60周以上的营养添加培养物中的微生物多样性或甲烷产量。这里介绍的U1473A站点的工作代表了超低扩展脊和通常难以到达的下洋壳的基底岩石样本，增加了我们对这个很少研究的环境中存在的微生物生命的理解，并为Enceladus等海洋世界系统下面的基底提供了一个模拟。重要性海底以下的下层洋壳是地球上开发最少的栖息地之一。来自西南印度洋海脊(SWIR)的岩石与其他海洋行星和卫星上的岩石环境相似。研究这种环境有助于我们增加对太阳系中其他地下岩石环境中生命的理解，我们还没有能力进入这些环境。在一次对SWIR的探险中，我们在海底地壳钻了780米，收集了50多个岩石样本，以计算驻留微生物的数量，并确定他们是谁。我们还选择了这些岩石中的一些进行实验，为它们提供不同的营养物质，以探索适合生长的能源和碳源。我们发现，栖息微生物的数量和群落结构随着深度的不同而变化。此外，添加的营养物质并没有以可预测的方式塑造微生物多样性。
The lower oceanic crust below the seafloor is one of the most poorly explored habitats on Earth. The rocks from the Southwest Indian Ridge (SWIR) are similar to rock environments on other ocean-bearing planets and moons. ABSTRACT International Ocean Discovery Program Expedition 360 drilled Hole U1473A at Atlantis Bank, an oceanic core complex on the Southwest Indian Ridge, with the aim of recovering representative samples of the lower oceanic crust. Recovered cores were primarily gabbro and olivine gabbro. These mineralogies may host serpentinization reactions that have the potential to support microbial life within the recovered rocks or at greater depths beneath Atlantis Bank. We quantified prokaryotic cells and analyzed microbial community composition for rock samples obtained from Hole U1473A and conducted nutrient addition experiments to assess if nutrient supply influences the composition of microbial communities. Microbial abundance was low (≤104 cells cm−3) but positively correlated with the presence of veins in rocks within some depth ranges. Due to the heterogeneous nature of the rocks downhole (alternating stretches of relatively unaltered gabbros and more significantly altered and fractured rocks), the strength of the positive correlations between rock characteristics and microbial abundances was weaker when all depths were considered. Microbial community diversity varied at each depth analyzed. Surprisingly, addition of simple organic acids, ammonium, phosphate, or ammonium plus phosphate in nutrient addition experiments did not affect microbial diversity or methane production in nutrient addition incubation cultures over 60 weeks. The work presented here from Site U1473A, which is representative of basement rock samples at ultraslow spreading ridges and the usually inaccessible lower oceanic crust, increases our understanding of microbial life present in this rarely studied environment and provides an analog for basement below ocean world systems such as Enceladus. IMPORTANCE The lower oceanic crust below the seafloor is one of the most poorly explored habitats on Earth. The rocks from the Southwest Indian Ridge (SWIR) are similar to rock environments on other ocean-bearing planets and moons. Studying this environment helps us increase our understanding of life in other subsurface rocky environments in our solar system that we do not yet have the capability to access. During an expedition to the SWIR, we drilled 780 m into lower oceanic crust and collected over 50 rock samples to count the number of resident microbes and determine who they are. We also selected some of these rocks for an experiment where we provided them with different nutrients to explore energy and carbon sources preferred for growth. We found that the number of resident microbes and community structure varied with depth. Additionally, added nutrients did not shape the microbial diversity in a predictable manner.