Pyrite: A Crucial Mineral and Surface for Microbial Life in Extreme Hydrothermal Environments

在陆地和深海热液喷口等高温（超嗜热菌）生态系统中茁壮成长的生物，挑战了我们对生命最高温度限制的物理和生化限制的理解，并激发了关于生命起源的新理论（例如Baross和Hoffman, 1985; Pace, 1991）。这些超嗜热生物与所有生命的共同祖先（来自小亚基rRNA和基因复制数据）最密切相关，这支持了生命起源于高度还原的高温环境的理论，例如在热液喷口系统中遇到的环境。最近，科学家们提出了一种合成第一批生命分子的机制，其中黄铁矿可以以氢为产物进行非生物合成，为第一批代谢循环的进化奠定了框架。本研究的中心假设认为，黄铁矿的非生物合成为最深层生命谱系的化学自养代谢提供了隔离能量来源的基本特性。Drs。Luther和Reysenbach认为，在极端的化学和物理环境下，微生物可以利用黄铁矿表面提供的资源进行持续的代谢。他们还认为，这些生物将密切代表可能占据类似极端栖息地的早期生命形式。此外，由于存在分子系统发育证据表明，这些最深处的嗜热谱系生活在深海热液喷口富含铁和硫的环境中，因此他们很好地验证了这些断言。本研究的目的是：1。探讨黄铁矿及其吸附的微量金属和简单无机分子是否会介导高温水体环境中微生物群落结构。2. 通过同时测量FeS和硫化氢来确定是否可以预测黄铁矿的合成。该项目明确解决了LExEn研究计划的大部分主要任务。在这项跨学科研究中，这些合作者将结合分子遗传学方法和原位地球化学方法，研究在极端氧化还原和温度梯度存在的极端栖息地中茁壮成长的微生物的多样性、生态学和进化史。

9714302 Luther PROJECT SUMMARY Organisms that thrive in high temperature (hyperthermophiles) ecosystems such as at terrestrial and deep-sea hydrothermal vents, have challenged our understanding of the physical and biochemical constraints on the upper temperature limits for life and stimulated new theories on how life originated (e.g. Baross and Hoffman, 1985; Pace, 1991). These hyperthermophiles are the most closely related to the universal ancestor for all life (from small subunit rRNA and gene duplication data) which supports the theory that life arose in highly reduced, high temperature environments such as those encountered at hydrothermal vent systems. Recently scientists proposed a mechanism for the synthesis of the first molecules for life in which pyrite can be synthesized abiotically with hydrogen as a product, laying the framework for the evolution of the first metabolic cycles. The central hypothesis of this study maintains that the abiotic synthesis of pyrite provides the essential properties for sequestering the energy sources for chemoautotrophic metabolism of the deepest lineages of life. Drs. Luther and Reysenbach believe that under an extreme chemical and physical environment microorganisms can utilize the resources provided on the pyrite surfaces for sustained metabolism. They also believe that these organisms will closely represent early life forms that may have occupied similar extreme habitats. Furthermore, since molecular phylogenetic evidence exists that the deepest of these thermophilic lineages inhabit iron and sulfidic-rich environments at deep-sea hydrothermal vents, they are well- positioned to test these assertions. The objective of this research are: 1. To establish whether pyrite and the associated adsorbed trace metals and simple inorganic molecules will mediate the microbial community structure in high temperature aquatic environments. 2. To determine whether pyrite synthesis can be predicted, through the simultaneous measurement of FeS and hydrogen sulfide. This project clearly addresses most of the primary mandates of the LExEn research program. In this interdisciplinary study these collaborators will integrate molecular genetic approaches with in situ geochemistry to study the diversity, ecology, and evolutionary history of the microorganisms thriving in extreme habitats where intense redox and temperature gradients exist.