Ocean Crust Alteration and the Deep Biosphere

摘要：本研究为模拟和解释海洋地壳深层生物圈中微生物的存在和作用提供了理论框架和工具。它还将使我们能够预测微生物的栖息地和代谢机制，这将确保通过海底勘探和钻探进入深层生物圈所需的昂贵投资获得更大的回报。这项研究利用来自地下玄武岩含水层的漫射流体和蚀变岩石的现有数据来量化微生物可以利用的能量供应。编纂基本生物分子、酶和地质物质之间相互作用的工作，将允许预测微生物代谢机制，作为温度、压力、流体成分和岩石蚀变程度的函数。这项工作的理由来自这样一个事实，即海洋地壳中的深层生物圈是由海水和火成岩之间的不平衡维持的。根据对玄武岩和其他地壳火成岩氧化蚀变程度的观察，最近的工作提供了支持深层生物圈的能量供应的估计，这表明在变化的火成岩中所含的深层生物圈的部分可能与海底沉积物中的部分相媲美。因此，深层生物圈已成为地球探测的主要目标，但由于缺乏对地下微生物特征和代谢需求的了解，使我们无法充分调查它们的存在和重要性。这项研究解决了这个问题。更广泛的影响：这项工作的更广泛的影响包括开发微生物过程的热力学框架，该框架将在互联网上公开提供。这项工作的结果也跨越到生物学领域，可以被环境科学家用于有毒废物的生物修复和工程纳米颗粒的下游影响。这项工作还支持研究生和本科生的培训，并为亚利桑那州立大学开放之家和深层生物圈博物馆提供展示。工作将补充NSF的IODP和海洋观测系统计划的活动。

ABSTRACT-0752541 (Shock)Intellectual Merit: This research provides the theoretical framework and tools needed to model and interpret the increasing evidence for the presence and actions of microbes in the deep biosphere in oceanic crust. It will also allow us to make predictions of microbial habitation and metabolic mechanisms which will ensure greater returns on the costly investments required to access the deep biosphere through seafloor exploration and drilling. This research uses existing data on diffuse fluids and altered rocks from subsurface basalt aquifers to quantify the supply of energy that can be used by microbes. Work to codify the interactions between essential biomolecules and enzymes and geological materials will permit the prediction of mechanisms of microbial metabolism as function of temperature, pressure, fluid composition, and extent of rock alteration. Justification for the work comes from the fact that the deep biosphere in the oceanic crust is sustained by the disequilibrium between seawater and igneous rocks. Recent work provides estimates of the supply of energy that supports the deep biosphere derived from observations of the extent of oxidative alteration of basalts and other crustal igneous rocks that suggest the portion of the deep biosphere hosted in altering igneous rocks may rival that in seafloor sediments. As a result, the deep biosphere has become a major target for Earth exploration, but lack of knowledge of the signatures of and metabolic needs of microbes in the subsurface have prevented us from adequately investigating their presence and importance. This research attacks this issue. Broader Impacts: Broader impacts of the work include development of a thermodynamic framework for microbiological processes that will be made publicly available on the Internet. Results of the work also cross over into biology and can be used by environmental scientists for the bioremediation of toxic waste and the downstream impacts of engineered nanoparticles. The work also supports the training of graduate and undergraduate students and the creation of a display for the Arizona State University Open House and Museum on the deep biosphere. Work will complement activities in both NSF's IODP and Ocean Observing Systems Programs.