Biogeochemistry of carbon monoxide cycling in hypersaline and arid soil systems: novel insights from newly discovered extremely halophilic CO-oxidizing Euryarchaeota

广泛的研究表明，土壤是微量气体的主要来源和汇，在大气化学和全球气候制度中发挥重要作用。 然而，大多数研究都集中在森林，草地和耕地土壤，这些土壤在很大程度上经历了温和的条件（例如，温度和沉淀）。 干旱和半干旱土壤约占全球陆地总面积的三分之一，但相对较少受到关注。 盐渍土的面积比法国还大，约占农业用地总面积的18%，也被忽视了。 尽管如此，最近的工作结果与干旱和盐碱土壤表明，他们可能会大大有助于区域规模的一氧化碳（CO），微量气体，在大气中具有重要的监管功能的全球预算。 这里提出的研究将包括在犹他州，加州和俄克拉荷马州的盐碱地和干旱土壤中的CO循环的比较研究，分析干旱和盐碱地从大气中去除CO的能力，以及分析土壤基质中CO去除和生产之间的耦合。 这些结果将得到微生物群落和CO氧化微生物平行研究的补充，将提供对地球土壤主要类别的CO地球化学的全面了解。这里提出的工作将涉及多项任务。 钼依赖的CO氧化和缺氧CO生产之间的耦合程度，以及每一个在高盐CO循环中的作用将通过通量研究和土壤和沉积物培养在实验室实验中，旨在探测氧化和生产率，以及所涉及的生物。 支持CO氧化的条件范围的新的见解将来自活动的分析，在广泛的极端水的可用性，无论是异地和台式分析的土壤和沉积物将被用来评估限制CO氧化。 溶质应力与基质势应力的重要性将通过在一系列相似的水势范围内比较含盐和干旱系统来确定。 最后，从新的和现有的CO氧化分离株的基因组数据将被用来建立一个进化的历史钼依赖的CO氧化和其起源的地球生物学背景。这个项目将涉及研究生和本科生在项目的几个阶段。威斯敏斯特学院和犹他州大学的学生将参与实地研究，并接受生物地球化学和微生物多样性分析的培训。此外，路易斯安那州立大学“校园序列”项目的学生也将参与该项目。PI将通过路易斯安那州立大学的环境导师分会做出更多努力，招募代表性不足的学生。

Extensive research has shown that soils are major sources and sinks of trace gases that play important roles in atmospheric chemistry and global climate regimes. However, most of this research has focused on forest, grassland and cultivated soils that largely experience moderate conditions (e.g., temperature and precipitation). Arid and semi-arid soils, which account for about one-third of total global land area, have received relatively little attention. Saline soils, which account for an area larger than France, and constitute about 18% of total agricultural land area, have been also been overlooked. Nonetheless, results of recent work with arid and saline soils indicates that they may contribute significantly to regional-scale to global budgets of carbon monoxide (CO), a trace gas that has critical regulatory functions in the atmosphere. Research proposed here will include comparative studies of CO cycling in saline and arid soils in Utah, California and Oklahoma, analyses of the capacity of arid and saline soils to remove CO from the atmosphere, and analyses of the coupling between CO removal and production within the soil matrix. The results, which will be complemented by parallel studies of microbial communities and CO-oxidizing microbes, will provide a comprehensive understanding of CO biogeochemistry for a major category of Earth's soils. Work proposed here will involve multiple tasks. The extent of coupling between Mo-dependent CO oxidation and anoxic CO production, and the roles of each in hypersaline CO cycling will be addressed through flux studies and soil and sediment incubations in laboratory experiments designed to probe rates of oxidation and production as well as the organisms involved. New insights about the range of conditions that support CO oxidation will be derived from analyses of activity across a wide range of extremes in water availability; both ex situ and bench-top analyses of soils and sediments will be used to assess limits of CO oxidation. The importance of solute stresses versus matric potential stresses will be determined by comparisons of saline and arid systems across a range of similar water potentials. Finally, genomic data from new and existing CO-oxidizing isolates will be used to establish an evolutionary history for Mo-dependent CO oxidation and a geobiological context for its origin. This project will involve graduate and undergraduate students in several stages of the project. Students of Westminster College and University of Utah will be involved with field research, and receive training on biogeochemistry and microbial diversity analysis. In addition, students from the "Sequence the Campus" program of the Louisiana State University will be involved in the project. The PI will make additional efforts to recruit under-represented students through LSU's EnvironMentors Chapter.