日本和德國科學(xué)家最近發(fā)現(xiàn)海底之下10厘米至365米深的地層內(nèi)生存著大量古細菌,，這一發(fā)現(xiàn)將有助于了解生物進化和它們對環(huán)境的適應(yīng)過程。
日本海洋研究開發(fā)機構(gòu)和德國不來梅大學(xué)的科學(xué)家日前在英國《自然》雜志網(wǎng)絡(luò)版上報告說,，他們分析了從日本紀(jì)伊半島近海,、加拿大和秘魯近海,、黑海等世界16個海域挖掘的海底堆積物,。這些堆積物來自日、德等國探測船對水深幾百米至2000米的海洋底部進行的鉆探,。
根據(jù)美國科學(xué)家伍斯提出的學(xué)說,，生物可分為真細菌、古細菌和包括動植物在內(nèi)的真核生物三大類,。此前一直有看法認為,，海底之下的地層中主要生存著真細菌,。但日,、德科學(xué)家的最新分析結(jié)果卻表明，真細菌多生活在海底之下10厘米以內(nèi)的淺層堆積物中,，而更深處地層中古細菌平均占到87%,，真細菌只占13%。
科學(xué)家推測,，按照換算成碳元素來衡量,，整個地球海底之下地層中的古細菌總量可達900億噸，相當(dāng)于陸地土壤中各種微生物總量的3倍以上,。
古細菌是一類很特殊的細菌,，多生活在海底熱溢口以及高鹽、強酸或強堿性水域等極端環(huán)境中,。此次在海底發(fā)現(xiàn)大量古細菌,，將有助于研究古細菌如何適應(yīng)嚴(yán)酷的環(huán)境而獨立進化。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature advance online publication 20 July 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
Correspondence to: Kai-Uwe Hinrichs1 Correspondence and requests for materials should be addressed to K.-U.H. (Email: [email protected]).
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.
