Ocean sediment-basement interface Targeted Locus (Loci)

Previous studies of microbial abundance and geochemistry in deep marine sediments indicate a stimulation of microbial activity near the sediment-basement interface. Furthermore, the few studies thus far conducted in deep oceanic crust reveal an active microbial community in this habitat. Yet, the extent to which microbial communities in bottom sediments and underlying crustal habitats interact is unclear. Are microbial communities in sediments seeded from basement communities, or vice versa? If there is influence from one habitat type on the other, how far does this influence extend, both with vertical distance away from the interface and laterally along the flow path of fluids within basement? We propose to conduct tag pyrosequencing on samples from a spectrum of sediment-basement habitats to identify patterns in microbial community shifts across sediment-basement interfaces. Such comparisons will allow us to evaluate whether microbial groups from one habitat are found in another, and to examine whether members of the ''rare biosphere'' in one habitat come to dominate in another. Analysis of the pyrosequencing data will help us better understand how subsurface microbial communities are established and evolve, in addition to expanding our knowledge of microbial biogeography across sediment-basement interfaces in different oceanic basins.过往针对深海沉积物中微生物丰度与地球化学特征的研究表明，沉积物-基底界面（sediment-basement interface）附近的微生物活性受到显著激发。此外，目前已开展的少数深海洋壳相关研究显示，该生境中存在活跃的微生物群落。然而，深海沉积物与下伏地壳生境中的微生物群落究竟以何种程度相互作用，目前仍不明确。沉积物中的微生物群落是否源自基底群落，抑或基底群落源自沉积物？若两类生境间存在相互影响，则这种影响的传播范围如何？既包括沿界面垂直距离方向，也涵盖地壳内部流体运移路径的横向方向。本研究拟对一系列覆盖沉积物-基底生境梯度的样本开展标签焦磷酸测序（tag pyrosequencing），以解析沉积物-基底界面处微生物群落的演替模式。通过此类比对分析，我们能够评估某一生境中的微生物类群是否会出现在另一生境中，并检验某一生境中的“稀有生物圈（rare biosphere）”成员是否会在另一生境中占据主导地位。对该焦磷酸测序数据的分析将有助于我们更深入地理解地下微生物群落的构建与演化过程，同时拓展我们对不同大洋盆地内沉积物-基底界面微生物生物地理学的认知。