Collaborative Research: ETBC: Deep Crustal Biosphere: Microbial Cycling of Carbon

知识价值。在过去的二十年里，来自世界各地的研究在大陆和海洋的各种地质环境中揭示了地下微生物生态系统的范围和多样性。从极地永久冻土带和冰盖到赤道海洋沉积物，从200米深的可渗透含水层到4公里深的裂缝岩，从深层渗透带到油藏，发现了各种各样的细菌和古细菌组合，包括许多新物种。随着大陆和海洋地壳深度和温度的增加，地表气候变化和光球过程对地下微生物生态系统的影响减弱，而以有机和无机营养物质混合丰富地壳的类费托作用和辐射分解作用变得越来越重要。无论有机碳的来源如何，控制其生物降解为CO2和CH4的规则应该与石油储集层的规则相似。该项目的目标是确定这些规则，确定地下微生物生态系统对有机物生物降解的速率和极限，并确定谁应该对此负责。为了实现这些目标，研究人员将利用南非威特沃特斯兰德盆地（Witwatersrand Basin）矿井中易于接近的钻孔，深度从0.8公里到3.8公里，以检查浅层有机光合作用和深层非生物烃生物降解的程度和物种间相互作用。通过综合使用1)GCMS、HPLC和NMR表征DOC， 2) DOC、DIC、碳氢化合物、脂质和有机酸的13C分析，3)碳氢化合物的H同位素分析，4)CH4、DIC、DOC和脂质的14C分析，以及5)16S rRNA的稳定同位素探针（SIP），我们将描述1)化学自养产生的有机酸，2)非生物产生的碳氢化合物，3)产热有机酸和4)地表光球溶解有机质（DOC），到地表下微生物群落结构及其在碳代谢过程中的营养相互作用。这些分析将对从裂缝水中收集的浮游微生物群落进行，其年龄从数千年到数千万年不等。更广泛的影响。该研究计划将吸引本科生和毕业生进行跨学科的实践研究，他们将把同位素地球化学和有机地球化学分析与遗传分析结合起来。来自北美和南非的学生将参与实地和实验室研究，作为与南非科学家正在进行的合作的一部分。RNA-SIP孵育实验将伴随着分离实验，这将进一步扩大自由邦大学（UFS）的地下培养收集和遗传数据库，并加强其生物修复和生物技术工作。该项目将开始整合碳代谢方面的遗传、分类和功能多样性。研究人员将努力建立一个基于网络的地下微生物数据库，其中包含地下微生物的SEM/TEM图像库，可以下载用于新闻稿；作为画廊的一部分，我们将发起一个“世界上哪里有这种有机体？”，描述在哪里发现了相关的菌株或序列。该网站将为地下深处的微生物生物地理数据库提供开端。在得到矿业公司许可的情况下，抽样考察的录像将在网站上公布。该项目还将为威特沃特斯兰德盆地未开发的天然气储层的最佳开采和私营公司在南非开发二氧化碳封存项目提供基本的科学基础

Intellectual Merit. For the past two decades studies from around the world in a wide variety of geological environments in both continental and marine settings have revealed the extent and variety of subsurface microbial ecosystems. From polar permafrost and ice sheets to equatorial marine sediments, from permeable aquifers ~200 meters deep to fractured rock 4 km deep, from deep vadose zones to oil reservoirs, diverse assemblages of bacteria and archaea, including many novel species, have been discovered. As depth and temperature increase in both the continental and oceanic crust, the effects of changing surface climate and photospheric processes on the subsurface microbial ecosystem diminish while Fisher-Tropsch-like and radiolytic processes, which enrich the crust with a mixture of organic and inorganic nutrients, become increasingly important. Regardless of the origin of the organic carbon, the rules that govern its biodegradation to CO2 and CH4 should be similar to those for petroleum reservoirs. The goals of this project are to determine those rules, determine the rates and limits of the biodegradation of organic matter by subsurface microbial ecosystems, and determine who is responsible. To accomplish these goals, investigators will utilize the readily accessible boreholes present in the mines of the Witwatersrand Basin, South Africa, which range in depth from 0.8 to 3.8 km, to examine the extent of and the inter-species interactions involved in biodegradation of organic photosynthate in shallow depths and abiogenic hydrocarbons at great depth. By employing a combination of 1) GCMS, HPLC, and NMR characterization of the DOC, 2) 13C analyses of DOC, DIC, hydrocarbons, lipids, and organic acids, 3) H isotope analyses of hydrocarbons, 4) 14C analyses of CH4, DIC, DOC, and lipids, and 5) stable isotope probes (SIP) of the 16S rRNA, we will delineate the relative importance of 1) chemoautotrophically produced organic acids, 2) abiogenically produced hydrocarbons, 3) thermogenically produced organic acids and 4) dissolved organic matter (DOC) from the surface photosphere, to the subsurface microbial community structure and its trophic interactions during carbon metabolism. These analyses will be performed on planktonic microbial communities collected from fracture water ranging in age from thousands of years to tens of millions of years. Broader Impacts. The program of study will engage undergraduates and graduates in hands-on interdisciplinary research where they will integrate isotope geochemistry and organic geochemical analyses with genetic analyses. Students from North America and South Africa will participate in the field and laboratory research as part of an ongoing collaboration with South African scientists. The RNA-SIP incubation experiments will be accompanied by isolation experiments that will further enlarge the subsurface culture collection and genetic database at the Univ. of Free State (UFS) and enhance their bioremediation and biotechnology efforts. The project will begin to integrate the genetic, taxonomic and functional diversity with respect to carbon metabolism. Investigators will work to assemble a web-based subsurface microbial database with a gallery of SEM/TEM images of subsurface microorganisms that can be downloaded for press releases; and as part of the gallery we will initiate a "Where in the world does this organism occur?" describing where related strains or sequences have been found. The web site will provide the beginnings of a microbial biogeographical database for the deep subsurface. When permitted by the mining companies videos of the sampling expeditions will be posted on the web site. The project will also provide fundamental scientific underpinnings for optimal exploitation of untapped natural gas reservoirs in the Witwatersrand Basin and for the development of CO2 sequestration projects in South Africa by private firms