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

硒有时被称为“基本毒素”，对人类和生态系统的健康起着重要的作用。硒是大多数生物所必需的微量营养素。然而，在浓度升高的情况下，硒是一种有毒元素，越来越受到环境的关注。硒的生物有效性和毒性在很大程度上取决于化合物的形式或氧化状态。微生物，包括真菌，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还没有解决，因此限制了人们对它们在自然界中的具体贡献的了解。这项研究将使用基因组启动的方法，检查和解决相关的真菌生物地球化学过程，这些过程改变了硒的形态形成，并最终影响了硒在自然界中的命运和分布。拟议的研究结果还将直接为硒生物修复的新技术提供信息，并将引起监管或管理硒问题的政府和当地利益相关者的额外兴趣。通过正式的学生培训和与当地博物馆合作参与公共科学交流，该项目将进一步吸引、告知和激励学生和公众，使他们了解微生物在维持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自然界中硒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，这些分子机制和途径有助于一系列与环境相关的子囊菌真菌将可溶性、有毒的硒阴离子(亚硒酸盐和亚硒酸盐)好氧还原转化为不溶的Se(0)和有机的挥发性Se(-II)化合物。具体的研究目标是：(1)确定真菌在有氧环境中还原亚硒酸盐的机理，(2)评估关键营养物质和微量金属对真菌Se转化机制和反应产物的影响，(3)研究Se生物矿化产物的粒度、形态和结构与真菌生长条件和Se还原途径的关系。基因组激活的方法将通过将基因和蛋白质的表达与特定功能联系起来，从而导致硒生物矿物质和有机硒化合物，从而阐明有助于硒减少的基因和蛋白质。这种方法将导致这些常见真菌物种的基因调控网络的发展，这将非常有利于预测环境或生物变化对Se形态形成的影响，并将进一步促进环境和生物科学中真菌研究的进展。该项目由地球科学部的地球生物学和低温地球化学计划和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智力优势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.