LExEn: Role of Atmospheric Trace Gases in Microbial Colonization and Succession on Recent Lava Flows

gary M. KingDrs。缅因大学的加里·m·金和马萨诸塞大学阿姆赫斯特分校的克劳斯·努斯林获得了美国国家科学基金会极端环境中的生命（LExEn）项目的资助，以确定大气微量气体在近期熔岩流中微生物定居和演为中的作用。在地球历史的大部分时间里，火山活动在陆地生态系统的发展中发挥了重要作用，并继续塑造着目前的陆地环境。随着时间的推移，熔岩和火山灰的沉积形成了支持复杂、高产生物群落的表面。然而，年轻的或最近喷出的熔岩代表了极端的环境，这些环境中几乎没有维持生命所需的主要营养物质。无论是有机物还是固定形式的氮（如铵或硝酸盐）都不容易在年轻熔岩的基质内或基质上获得。因此，微生物在熔岩的早期定植需要外源营养物质。最近对年轻的夏威夷熔岩的观察表明，大气为早期微生物的定居提供了重要的碳和能量来源。特别是，微量气体，如氢气和一氧化碳（可能还有甲烷）作为底物，为功能多样的微生物的新陈代谢提供燃料。在这些微生物中，有利用大气氮作为细胞氮来源的细菌，也有与植物形成重要共生关系的物种。微生物利用微量气体的性质定殖年轻的熔岩将是这个LExEn研究工作的主要重点。在基拉韦厄火山附近进行的各种实地和实验室研究将记录熔岩年龄（强调0-300年的时间序列）、微生物生物量、微量气体利用（氢、一氧化碳和甲烷）和降水制度（如湿润与干燥）之间的关系。从熔岩中提取的基因组DNA将用于确定不同年龄和气候梯度的微生物群落的多样性，以及这些群落中特定功能群的多样性。最后，这项研究将包括利用年轻熔岩中的微生物来丰富、分离和表征新的微量气体，并确定这些分离物在原位的意义。这项研究有望对极端环境下微生物的生存和动力学产生新的见解，这与理解当代和古代陆地系统以及可能存在于其他行星上的系统有关。

DEB-0085495Gary M. KingDrs. Gary M. King of the University of Maine and Klaus Nusslein of the University of Massachusetts-Amherst have been awarded a grant from the NSF Life in Extreme Environment (LExEn) program to determine the role of atmospheric trace gases in microbial colonization and succession on recent lava flows. Volcanic activity has played an important role in the development of terrestrial ecosystems for much of Earth's history, and continues to shape terrestrial environments at present. Deposition of lava and tephra result in surfaces that over time support complex, highly productive biological communities. However, young or recently extruded lavas represent extreme environments that contain few of the major nutrients necessary for sustaining life. Neither organic matter nor a fixed form of nitrogen (e.g., ammonium or nitrate) are readily available within or on the matrix of young lava. Thus, early colonization of lava by microbes requires a source of exogenous nutrients. Recent observations of young Hawaiian lava indicate that the atmosphere provides a significant source of carbon and energy for early microbial colonization. In particular, trace gases such as hydrogen and carbon monoxide (and possibly methane) serve as substrates that fuel the metabolism of functionally diverse microbes. Among these microbes are bacteria that use atmospheric nitrogen as a source of cellular nitrogen, and species that form important symbioses with plants. The nature of trace gas utilization by microbes colonizing young lavas will be the primary focus of this LExEn research effort. A variety of field and laboratory studies in the vicinity of the Kilauea volcano will document relationships among lava age (emphasizing chronosequences from 0-300 yr), microbial biomass, trace gas utilization (hydrogen, carbon monoxide and methane) and precipitation regimes (e.g., moist versus dry). Extractions of genomic DNA from lava will be used to determine the diversity of microbial communities across age and climate gradients, and the diversity of specific functional groups within these communities. Finally, the research will include efforts to enrich, isolate and characterize novel trace-gas utilizing microbes from young lava and to determine the significance of such isolates in situ. The research is expected to yield new insights about the survival and dynamics of microbes in extreme environments relevant for understanding both contemporary and ancient terrestrial systems as well as systems that might exist on other planets.