日本和德国科学家最近发现海底之下10厘米至365米深的地层内生存着大量古细菌,这一发现将有助于了解生物进化和它们对环境的适应过程。
日本海洋研究开发机构和德国不来梅大学的科学家日前在英国《自然》杂志网络版上报告说,他们分析了从日本纪伊半岛近海、加拿大和秘鲁近海、黑海等世界16个海域挖掘的海底堆积物。这些堆积物来自日、德等国探测船对水深几百米至2000米的海洋底部进行的钻探。
根据美国科学家伍斯提出的学说,生物可分为真细菌、古细菌和包括动植物在内的真核生物三大类。此前一直有看法认为,海底之下的地层中主要生存着真细菌。但日、德科学家的最新分析结果却表明,真细菌多生活在海底之下10厘米以内的浅层堆积物中,而更深处地层中古细菌平均占到87%,真细菌只占13%。
科学家推测,按照换算成碳元素来衡量,整个地球海底之下地层中的古细菌总量可达900亿吨,相当于陆地土壤中各种微生物总量的3倍以上。
古细菌是一类很特殊的细菌,多生活在海底热溢口以及高盐、强酸或强碱性水域等极端环境中。此次在海底发现大量古细菌,将有助于研究古细菌如何适应严酷的环境而独立进化。(生物谷Bioon.com)
生物谷推荐原始出处:
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: khinrichs@uni-bremen.de).
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.