CAREER: Rusting the Earth: the mechanisms and mineralogy of microbial Fe oxidation

微生物数量众多，分布广泛，代谢多样，几乎影响着地球上的每一个环境。年代的表面。铁氧化微生物（FeOM）可能一直在氧化或生锈。在地球上存在了数十亿年在接近中性的pH环境中，FeOM形成氧化铁，吸附金属、有机物和其他营养物质，影响元素的生物有效性、碳循环以及土壤和水质。在非生物氧化速率缓慢的环中性含水层和土壤中，微生物铁氧化预计会加速低氧、富铁（II）环境中的铁氧化速率。然而，很少有中性FeOM物种被明确地证明可以氧化铁；因此，我们对中性ph下功能的FeOM的多样性，遗传学和生物化学知之甚少。我的总体目标是对铁微生物氧化进行综合的微生物学，生物化学，矿物学和地球化学理解，以便准确描述地球上现代和古代铁循环。我们首先需要开发识别和量化环中性微生物Fe氧化及其效应的方法，因此本项目的研究目标如下：(1)从地下水中分离和表征新型FeOM，从而扩大目前有限的FeOM多样性知识；(2)发现参与铁氧化的关键基因/蛋白候选基因，以深入了解生物（地球）化学机制，并为我们提供分析铁氧化和识别（元）基因组遗传能力的能力；(3)对分离株的C代谢和相关基因进行表征，了解微生物铁氧化剂如何影响C循环。这项工作将涉及培养和生理特性、差异基因/蛋白表达、qPCR以及分离基因组和环境16S rRNA等基因的测序和分析。我们将与位于DE和PA的NSF Christina River Basin Critical Zone Observatory （CRB-CZO）合作，使用CRB-CZO站点作为新型FeOM的来源，并作为我们检测FeOM存在和活动的新方法的试验场。研究主题将融入教育活动，培养学生的创造性思维和跨学科工作。创造力和跨学科的科学思想对于推动我们的社会和解决环境问题所需的创新和解决问题至关重要。这些技能需要实践，所以主要的教育目标是：(1)发展一个以探究为基础的本科地球微生物课程；(2)为一个？野外微生物！？为Serviam学院代表性不足的女中学生开设的科学模块。我还将在项目过程中培养一名博士后研究员和一名博士生。这项研究将被纳入持续的推广计划，包括学校演讲、教师研讨会、大学？每年的海岸日、科学咖啡馆以及其他由DE Sea Grant办公室组织的机会。

Microbes are numerous, widespread, and metabolically-versatile organisms, impacting virtually every environment on Earth?s surface. Fe-oxidizing microorganisms (FeOM) have likely been oxidizing, or ?rusting,? the Earth for billions of years. In near-neutral pH environments, FeOM form iron oxyhydroxides, which adsorb metals, organics, and other nutrients, affecting element bioavailability, C cycling, and soil and water quality. Microbial Fe oxidation is predicted to accelerate Fe oxidation rates in low oxygen, Fe(II)-rich environments found in circumneutral aquifers and soils, where abiotic oxidation rates are slow. However, few neutrophilic FeOM species have been unambiguously shown to oxidize Fe; therefore we know little about the diversity, genetics, and biochemistry of FeOM that function at neutral pH. My overall aim is to develop an integrated microbiological, biochemical, mineralogical and geochemical understanding of Fe microbial oxidation, in order to accurately describe modern and ancient Fe cycling on Earth. We first need to develop methods to recognize and quantify circumneutral microbial Fe oxidation and effects, so this project has the following research objectives: (1) Isolate and characterize novel FeOM from groundwater and thus expand the currently limited knowledge of FeOM diversity; (2) Discover candidates for key genes/proteins involved in Fe oxidation, to gain insight into bio(geo)chemical mechanisms and to give us the abilities to assay Fe-oxidation and recognize the genetic capability in (meta)genomes; (3) Characterize C metabolism and related genes in isolates, to understand how microbial Fe oxidizers can influence C cycling. This work will involve a combination of culturing and physiological characterization, differential gene/protein expression, qPCR, as well as sequencing and analysis of isolate genomes and environmental 16S rRNA and other genes. We will work in conjunction with the NSF Christina River Basin Critical Zone Observatory (CRB-CZO) in DE and PA, using CRB-CZO sites as a source of novel FeOM and as a testing ground for our new methods for detecting FeOM presence and activity. The research themes will be integrated into educational activities that train students to think creatively and work across disciplines. Creativity and interdisciplinary scientific thought is vital to the innovation and problem-solving needed to advance our society and address environmental issues. Such skills take practice, so the main educational objectives are to (1) develop an inquiry-based undergraduate geomicrobiology class and (2) create a curriculum for a ?Microbes in the Wild!? science module for under-represented female middle school students in the Serviam Academy. I will also train a postdoctoral researcher and a PhD student over the course of the project. The research will be incorporated into continuing outreach programs, including school presentations, teacher workshops, the college?s annual Coast Day, Science Café, and other opportunities organized by the DE Sea Grant office.