近年來對(duì)來自海床下面深層的沉積物樣品所做的研究工作，顯示了一個(gè)以前隱藏的,、巨大的深層微生物細(xì)胞生物圈,。鉆探考察的結(jié)果表明，這種生態(tài)系統(tǒng)包含一個(gè)相當(dāng)多樣化的細(xì)菌（Bacteria）和古細(xì)菌（Archaea）種群,，但這兩組微生物中哪一組居支配地位卻一直是一個(gè)非常有爭議的話題,。
根據(jù)對(duì)脂質(zhì)（它們能夠反映在來自大范圍亞表層環(huán)境的亞表層沉積物中存在活細(xì)胞）所做研究進(jìn)行的一項(xiàng)新的分析表明，在這個(gè)生態(tài)系統(tǒng)中居支配地位的是古細(xì)菌,，而不是細(xì)菌,。根據(jù)這項(xiàng)工作，研究人員還對(duì)該生物圈的大小做出了估計(jì)：其大小約為900億噸,。這個(gè)估計(jì)值與根據(jù)其他數(shù)據(jù)所做估計(jì)是一致的,，基本上相當(dāng)于全球植物生物質(zhì)總量的1/5。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
