South African Ultradeep Mines-Long Term Sites for Interdisciplinary Studies (LSLIS) into the Extreme Environment of the Deep Subsurface

9978267 Onstott最近的调查发现，在地表以下3.2公里的各种地壳环境中都有微生物群落(kmbls.)。只有一大把来自大陆地壳的深层微生物样本(0.5kmbls。)然而，存在，因为取心是昂贵的。1998年秋天，一个由美国、加拿大和瑞典大学和美国能源部国家实验室的科学家组成的考察队在南非超深金矿的岩层和地下水中寻找微生物。这项研究的目的是确定这些绵延3千米的矿井是否可以随时进入当地的地下微生物群落，以及地下水的辐射分解是否为微生物提供了营养来源。岩石、水和生物膜样本是从其中几个矿场采集的，深度从0.8到3.2千米不等。初步结果表明，地下水和岩石中存在多种嗜热微生物。其中一些微生物代表新物种，耐辐射，似乎独特地适应了它们产生的地球化学和水文地壳环境。此外，有证据表明，这些微生物大多是原生的，而不仅仅是污染的结果。PIS计划建立一个为期5年的观察和样本采集计划，以分析南非大陆深部岩石圈中的微生物群落，并解决以下假设，这些假设对于洞察潜在的外部生物生态位以及微生物如何在相对极端的环境中适应和生存至关重要。1.地下深层自养微生物群落是否在异养群落中占优势？2.深层地下微生物群落是否在能量和分解代谢资源方面是自给自足的，还是它们最终都依赖于从现今地表生物圈或古代埋藏的化石燃料中提供的有机成分？3.地下微生物活动的地球化学估计是否表明细胞寿命在几个世纪的数量级，如果是，这些比率是否与在低水平电离辐射下的长期生存兼容？4.流体裂缝中存在的微生物群落在功能和系统发育上是否与岩石基质中的微生物群落不同。为了解决上述研究假设，PI将改善浓缩作用，在PLFA和DNA分析的检测限度和速度方面，开发培养和分离技术，并开发用于量化深井中就地微生物活动的仪器。

9978267Onstott Recent investigations have identified microbial communities in various crustal environments down to 3.2 kilometers below the surface (kmbls.). Only a hand full of deep microbial samples from continental crust (0.5 kmbls.) exist, however, because coring is expensive. In the fall of 1998, an expedition of scientists from the USA, Canadian, and Swedish universities and U.S. DOE National labs searched the rock strata and groundwater of the ultradeep Au mines of South Africa for microorganisms. The goal of this research was to determine whether these mines, which extend 3 kmbls., offer ready access to indigenous, subsurface microbial communities and whether radiolysis of groundwater provides a nutrient source for the microorganisms. Rock, water and biofilm samples were collected from several of these mines at depths ranging from 0.8 to 3.2 kmbls. Preliminary results indicate that a variety of thermophilic microorganisms are present in the groundwater and rock. Some of these microorganisms represent novel species, radiation tolerant and appear uniquely adapted to the geochemical and hydrological crustal environment from which they were derived. Furthermore, evidence indicates that most of these microorganisms are autochthonous and not simply the result of contamination. PIs plan to establish a 5 year observation and sample acquisition program to analyze the microbial communities in the deep continental lithosphere of South Africa and address the following hypotheses, which are critical to gaining insight into potential exobiological niches and into how microorganisms can adapt and survive in relatively extreme environments. 1. Do autotrophic microbial communities dominate over heterotrophic communities in the deep subsurface?2. Are there deep subsurface microbial communities that are self-sufficient in terms of their energy and catabolic resources or do they all ultimately rely upon organic constituents supplied from the present surface biosphere or ancient buried fossil fuels?3. Are the cell lifetimes on the order of centuries as suggested by geochemical estimates of subsurface microbial activity and, if so, are these rates compatible with long term survival under low levels of ionizing radiation?4. Are microbial communities present in fluid fractures functionally and phylogenetically distinct from those present within the rock matrix.To address the above research hypotheses, PIs will improve enrichment, culturing and isolation technologies, in the detection limits for and rapidity of PLFA and DNA analyses, and develop instruments for quantifying in situ microbial activity within deep boreholes.