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

对硫和铁等氧化还原活性元素的深入了解是影响诸如深海海洋转变、酸性气体和石油演化、热液化学和生命起源、向海洋供应铁、工业脱硫、农业硫循环和金属流动性等问题的关键。数十亿年来，微生物一直是硫循环的潜在重要组成部分（Johnston et al., 2005; Mojzsis et al., 2007），但微生物与单质硫之间的许多基本相互作用尚不清楚。推进我们对这些系统行为的理解需要深入研究细胞（细菌、古细菌和真核生物）、矿物质（尤其是纳米颗粒）和水化学（尤其是氧化还原物种形成）之间的详细相互作用。知识优势：单质硫以体相和纳米粒相的形式存在，可以被微生物用于所有3种主要的分解代谢途径，通过作为电子受体、供体，或者在歧化的情况下两者兼而有之。溶解的硫也与单质硫相互作用，这些硫还可以与金属反应，最重要的是铁。微生物必须溶解单质硫才能对其进行代谢，但这种矿物与其他已被很好地研究过的微生物-矿物相互作用的矿物（例如Hernandez和Newman, 2001； Childers等人，2002；Burgon等人，2003;Lovley, 2008; Newman, 2008）有着根本的不同。单质硫的增溶可以通过与有机配体的相互作用或与其他硫种的相互作用来完成，形成新的可溶性中间体，如多硫化物。研究者建议开发一种综合的原位分析能力，在现场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：在许多环境中，元素硫的大小和表面特征是控制生物和非生物反应中硫循环的关键成分。更广泛的影响：硫系统中基本细胞-矿物质-氧化还原相互作用的进展提供了一个机会，将一些令人兴奋的教育经验整合到健康，政策和法律领域的利益相关者和专业人士的研究目标中，这些研究目标将产生对硫基微生物和元素循环的广泛研究的变革性见解。硫的种类和矿物受到许多已知生物的重要影响，但所提出的元素硫粒度/特征和氧化还原物种形成的详细程度从未得到应用。当比较多年来对氧化铁-微生物相互作用的详细调查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重要的新见解。通过对硫系统的这些研究所获得的知识的应用，可以应用于更广泛地思考影响人类健康问题的类似细胞-矿物质-氧化还原相互作用。这为促进科学家的培训提供了机会，以便与非科学公众交流结果，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。一系列的课程和专业研讨会将被开发，以及一系列的学习模块，说明基本的细胞-矿物质-氧化还原相互作用，让学生和专业人士亲身体验地球化学、矿物学和微生物数据是如何收集、评估、评估和辩论的，以获得可靠的信息。利益相关者参与科学数据收集、评估和辩论的实践，并结合对具有更好沟通技巧的科学家的培训，不仅代表了科学家准备工作的进步，而且也代表了与这些科学家一起工作的专业人员的准备工作的进步。

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.