CAREER: Fundamental cell-mineral-redox interactions in the sulfur system

对硫和铁等氧化还原活性元素的更多了解，是影响海洋深部过渡、含硫油气演化、热液化学和生命起源、海洋铁供应、工业脱硫、农业硫循环和金属移动性等问题的关键。数十亿年来，微生物一直是硫磺循环的潜在重要组成部分(Johnston等人，2005年；Mojzsis等人，2007年)，但微生物与元素硫之间的许多基本相互作用尚不清楚。要想加深我们对这些系统行为的理解，需要深入研究细胞(细菌、古生物和真核生物)、矿物(特别是纳米颗粒)和水化学(特别是氧化还原物种形成)之间的详细相互作用。智力上的优点：元素硫以块状和纳米颗粒的形式存在，可以被微生物作为电子受体和供体，或者在歧化反应中基本上两者兼而有之，从而被微生物用于所有三种主要的分解代谢途径。溶解的硫物种也与元素硫相互作用，这些物种还可以与金属反应，最重要的是铁。微生物必须溶解元素硫才能使其代谢，但这种矿物从根本上不同于研究了微生物-矿物相互作用的其他矿物，例如氧化铁矿物(例如Hernandez和Newman，2001；Childers等人，2002；Burgon等人，2003；Lovley，2008；Newman，2008)。元素硫的增溶可以通过与有机配体的相互作用或与其他硫物种的相互作用来实现，形成新的可溶性中间体，如多硫化物。研究人员建议发展一种综合的现场分析能力，在野外和实验室测试中研究硫的形态和元素硫矿物学，以解决以下假设：元素硫的大小和表面特征是许多环境中生物和非生物反应中控制硫循环的关键成分。广泛的影响：硫系统中基本细胞-矿物-氧化还原相互作用的进展提供了一个机会，整合一些令人兴奋的教育经验，使利益相关者和专业人员参与到健康、政策和法律领域，其研究目标将对硫基微生物和元素随时间循环的广泛研究以及与环境相关的系统产生有价值的变革见解。硫磺物种和矿物受到许多已知生物的重要影响，但元素硫颗粒大小/特征和氧化还原物种形成的详细程度从未被应用过。当比较多年来详细研究氧化铁-微生物相互作用所获得的丰富信息时(Newman，2008)，对涉及硫的基本微生物-矿物-氧化还原相互作用的详细调查可能会产生关键的新见解。通过这些硫磺系统研究获得的知识的应用可以应用于更广泛的思考，即影响人类健康问题的类似细胞-矿物-氧化还原相互作用。这为促进科学家与非科学公众交流成果提供了机会，并为利用矿物学、地球化学和微生物信息解决石棉矿物暴露、地下水砷污染和硒毒性等问题的医疗专业人员、政策制定者和法律专业人员提供培训。将开发一系列课程和专业研讨会，以及一系列说明基本细胞-矿物-氧化还原相互作用的学习模块，让学生和专业人员亲身体验如何收集、评估、评估和辩论地球化学、矿物学和微生物数据，以获得可靠的信息。利益攸关方参与科学数据收集、评估和辩论的实践，并结合对具有更好沟通技能的科学家的培训，不仅是在培养科学家方面的进步，而且也是在培养将与这些科学家一起工作的专业人员方面的进步。

Greater understanding of redox-active elements like sulfur and iron are key in the processes that affect problems such as ocean transitions through deep time, sour gas and oil evolution, hydrothermal chemistry and the origins of life, the supply of iron to the sea, industrial desulfurization, agricultural sulfur cycling, and metal mobility. Microorganisms have been a potentially important part of sulfur cycling for billions of years (Johnston et al., 2005; Mojzsis et al, 2007), yet many of the fundamental interactions between microorganisms and elemental sulfur are not understood. Advancing our understanding of how these systems behave requires delving into the detailed interactions between cells (bacterial, archaeal, and eukaryotic), minerals (especially nanoparticles), and water chemistry (especially redox speciation).Intellectual Merit: Elemental sulfur occurs as bulk and nanoparticulate phases and can be utilized by microorganisms for all 3 major catabolic paths through use as an electron acceptor, donor, or essentially both in the case of disproportionation. Dissolved sulfur species also interact with elemental sulfur, and those species can additionally react with metals, most importantly iron. Microorganisms must solubilize elemental sulfur in order to metabolize it, but this mineral is fundamentally different from other minerals where microbe-mineral interactions have been well studied, such as iron oxide minerals (for example Hernandez and Newman, 2001; Childers et al., 2002; Burgon et al., 2003; Lovley, 2008; Newman, 2008). Solubilizing elemental sulfur can be accomplished through interaction with organic ligands or through interactions with other sulfur species to form new soluble intermediates such as polysulfides. Investigator proposes to develop a combined in situ analytical capability to investigate sulfur speciation and elemental sulfur mineralogy in field and laboratory tests to address the following hypothesis: The size and surface character of elemental sulfur is a key component controlling sulfur cycling in biotic and abiotic reactions in many environments.Broader Impacts: Advances in fundamental cell-mineral-redox interactions in the sulfur system provide an opportunity to integrate some exciting educational experiences to engage stakeholders and professionals in health, policy, and legal fields with research goals that will yield transformative insights of value to the broad study of sulfur-based microorganisms and element cycling through time and in environmentally relevant systems. Sulfur species and minerals are importantly affected by a number of known organisms, but the level of detail proposed for elemental sulfur particle size/character and redox speciation has never been applied. When comparing the wealth of information that has come from years of investigating detailed iron oxide-microbe interactions (Newman, 2008), a detailed investigation of fundamental microbe-mineral-redox interactions involving sulfur may yield critical new insights. The application of the knowledge gained through these investigations of the sulfur system can be applied to broader thinking about similar cell-mineral-redox interactions that affect problems of human health. This opens an opportunity to advance the training of scientists to communicate results with the non-scientific public, and provide training to the medical professionals, policymakers, and legal professionals that utilize mineralogical, geochemical, and microbial information in addressing problems such as asbestos mineral exposure, groundwater arsenic contamination, and selenium toxicity. A series of classes and professional workshops will be developed, alongside a series of learning modules illustrating fundamental cell-mineral-redox interactions, to engage students and professionals in hands-on experiences of how geochemical, mineralogical, and microbial data is gathered, assessed, evaluated, and debated to arrive at reliable information. The participation of stakeholders in the practice of scientific data collection, evaluation, and debate integrated with the training of scientists with better communication skills represents not only an advance in the preparation of scientists, but an advance also in preparing professionals who will work with those scientists.