近年来对来自海床下面深层的沉积物样品所做的研究工作，显示了一个以前隐藏的、巨大的深层微生物细胞生物圈。钻探考察的结果表明，这种生态系统包含一个相当多样化的细菌（Bacteria）和古细菌（Archaea）种群，但这两组微生物中哪一组居支配地位却一直是一个非常有争议的话题。
根据对脂质（它们能够反映在来自大范围亚表层环境的亚表层沉积物中存在活细胞）所做研究进行的一项新的分析表明，在这个生态系统中居支配地位的是古细菌，而不是细菌。根据这项工作，研究人员还对该生物圈的大小做出了估计：其大小约为900亿吨。这个估计值与根据其他数据所做估计是一致的，基本上相当于全球植物生物质总量的1/5。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 454, 991-994 (21 August 2008) | doi:10.1038/nature07174
Significant contribution of Archaea to extant biomass in marine subsurface sediments
Julius S. Lipp1, Yuki Morono2, Fumio Inagaki2 & Kai-Uwe Hinrichs1
Organic Geochemistry Group, Department of Geosciences and MARUM Center for Marine Environmental Sciences, University of Bremen, PO Box 330 440, 28334 Bremen, Germany
Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe B200, Nankoku, Kochi 783-8502, Japan
Deep drilling into the marine sea floor has uncovered a vast sedimentary ecosystem of microbial cells1, 2. Extrapolation of direct counts of stained microbial cells to the total volume of habitable marine subsurface sediments suggests that between 56 Pg (ref. 1) and 303 Pg (ref. 3) of cellular carbon could be stored in this largely unexplored habitat. From recent studies using various culture-independent techniques, no clear picture has yet emerged as to whether Archaea or Bacteria are more abundant in this extensive ecosystem4, 5, 6, 7. Here we show that in subsurface sediments buried deeper than 1 m in a wide range of oceanographic settings at least 87% of intact polar membrane lipids, biomarkers for the presence of live cells7, 8, are attributable to archaeal membranes, suggesting that Archaea constitute a major fraction of the biomass. Results obtained from modified quantitative polymerase chain reaction and slot-blot hybridization protocols support the lipid-based evidence and indicate that these techniques have previously underestimated archaeal biomass. The lipid concentrations are proportional to those of total organic carbon. On the basis of this relationship, we derived an independent estimate of amounts of cellular carbon in the global marine subsurface biosphere. Our estimate of 90 Pg of cellular carbon is consistent, within an order of magnitude, with previous estimates, and underscores the importance of marine subsurface habitats for global biomass budgets.
