日本和德國(guó)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(xì)菌,，這一發(fā)現(xiàn)將有助于了解生物進(jìn)化和它們對(duì)環(huán)境的適應(yīng)過(guò)程。
日本海洋研究開(kāi)發(fā)機(jī)構(gòu)和德國(guó)不來(lái)梅大學(xué)的科學(xué)家日前在英國(guó)《自然》雜志網(wǎng)絡(luò)版上報(bào)告說(shuō),，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(gè)海域挖掘的海底堆積物,。這些堆積物來(lái)自日,、德等國(guó)探測(cè)船對(duì)水深幾百米至2000米的海洋底部進(jìn)行的鉆探。
根據(jù)美國(guó)科學(xué)家伍斯提出的學(xué)說(shuō),，生物可分為真細(xì)菌,、古細(xì)菌和包括動(dòng)植物在內(nèi)的真核生物三大類(lèi),。此前一直有看法認(rèn)為，海底之下的地層中主要生存著真細(xì)菌,。但日,、德科學(xué)家的最新分析結(jié)果卻表明，真細(xì)菌多生活在海底之下10厘米以?xún)?nèi)的淺層堆積物中,，而更深處地層中古細(xì)菌平均占到87%,，真細(xì)菌只占13%。
科學(xué)家推測(cè),，按照換算成碳元素來(lái)衡量,，整個(gè)地球海底之下地層中的古細(xì)菌總量可達(dá)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(xì)菌是一類(lèi)很特殊的細(xì)菌,，多生活在海底熱溢口以及高鹽、強(qiáng)酸或強(qiáng)堿性水域等極端環(huán)境中,。此次在海底發(fā)現(xiàn)大量古細(xì)菌,，將有助于研究古細(xì)菌如何適應(yīng)嚴(yán)酷的環(huán)境而獨(dú)立進(jìn)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.
