CAREER: Genome-enabled investigations into the mechanisms and ecological controls on selenium transformations by fungi

硒（Se）是人体和生态系统的重要组成部分，也是人体的“必需毒素”。 硒是大多数生物体必需的微量营养素。 然而，在高浓度下，Se是一种日益引起环境关注的有毒元素。硒的生物利用度和毒性在很大程度上取决于化合物的形式或氧化态。包括真菌在内的微生物通过促进各种化学反应，在控制和转化硒的化学形态方面发挥着重要作用。然而，真菌促进硒转化的过程在很大程度上尚未解决，从而限制了它们在自然界中的具体贡献的知识。 使用基因组使能的方法，这项研究将检查和解决相关的真菌生物地球化学过程，改变硒形态，并最终影响自然界中硒的命运和分布。拟议研究的结果也将直接为硒生物修复的新技术提供信息，并将对政府和正在监管或管理硒问题的当地居民产生额外的兴趣。通过与当地博物馆合作进行正式的学生培训和参与公共科学传播，该项目将进一步参与，告知和激励学生和公众微生物在维护和改善地球整体健康方面发挥的重要作用。 为了更好地了解真菌对影响硒在自然界中命运的生物地球化学过程的影响，本研究将阐明目前尚未解决的分子机制和途径，这些机制和途径有助于可溶性有毒Se含氧阴离子（硒酸盐和亚硒酸盐）向不溶性Se（0）和有机挥发性Se（-II）化合物的好氧还原转化，这些化合物是由一系列与环境相关的子囊菌真菌产生的。 具体的研究目标是（1）确定真菌在好氧环境中还原硒酸盐和亚硒酸盐的机制;（2）评估关键营养物质和微量金属对真菌硒转化机制和反应产物的影响;（3）研究真菌生长条件和硒还原途径对硒生物矿化产物的粒度、形态和结构的影响。基因组使能的方法将阐明基因和蛋白质，有助于硒减少，通过连接其表达的特定功能，并产生硒生物矿物和有机硒化合物。这种方法将导致这些常见的真菌物种的基因调控网络的发展，这将是非常有益的预测环境或生物变化对硒形态的影响，并将进一步有利于环境和生物科学中的真菌研究的进步。 该项目由地球科学部的地球生物学和低温地球化学项目以及分子和细胞生物科学部的系统和合成生物学集群共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Selenium (Se), sometimes referred to as "the essential toxin", plays an important role in human and ecosystem health. Selenium is a required micronutrient for most living organisms. At elevated concentrations, however, Se is a toxic element of increasing environmental concern. Selenium bioavailability and toxicity largely depends on the form, or oxidation state, of the compound. Microorganisms, including fungi, play an important role in controlling and transforming Se chemical speciation by promoting a variety of chemical reactions. The processes by which fungi promote Se transformations, however, are largely unresolved, thus limiting knowledge of their specific contributions in nature. Using a genome-enabled approach, this research will examine and resolve the relevant fungal biogeochemical processes that transform Se speciation and ultimately influence the fate and distribution of selenium in nature. Results from the proposed research will also directly inform new technologies for Se bioremediation and will be of additional interest to government and local stake-holders who are regulating or managing Se issues. Through formal student training and engagement in public science communication in collaboration with local museums, this project will further engage, inform, and inspire students and the public on the important role that microorganisms play in maintaining and improving the overall health of planet Earth. To better understand the impact of fungi on biogeochemical processes that influence the fate of selenium in nature, this research will illuminate the currently unresolved molecular mechanisms and pathways that contribute to the aerobic reductive transformation of soluble, toxic Se oxyanions (selenate and selenite) to insoluble Se(0) and organic, volatile Se(-II) compounds by a diverse suite of environmentally-relevant Ascomycete fungi. The specific research objectives are to (1) identify the fungal mechanisms of selenate and selenite reduction in oxic environments, (2) assess the effects of key nutrients and trace metals on fungal Se transformation mechanisms and reaction products, and (3) investigate particle size, morphology, and structure of Se biomineralization products with respect to fungal growth conditions and Se reduction pathway. The genome-enabled approach will elucidate the genes and proteins that contribute to Se reduction by linking their expression to specific functions and resulting Se biominerals and organoselenium compounds. This approach will lead to the development of gene regulatory networks for these common fungal species, which will be highly beneficial for predicting the effect of environmental or biological change on Se speciation and will further benefit the advancement of fungal research in environmental and biological sciences. This project is jointly funded by the Geobiology and Low-Temperature Geochemistry Program in the Division of Earth Sciences and the Systems and Synthetic Biology Cluster in the Division of Molecular and Cellular Biosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.