A Cellular Systems Analysis of Microbe-Arsenic Interactions

联合国将2005-2015年定为国际行动十年：“生命之水”，目的是使世界各国政府关注适合人类使用的淡水供应不断减少的问题。亚洲大部分地区的严重砷污染危机就是这个问题最引人注目的例子，尽管美国也有一些地区的饮用水供应中砷含量升高。砷在土壤和水中的去向、迁移和生态毒理高度依赖于调控自然界中砷生物地球化学循环的非生物和生物过程。现在已经知道，微生物催化的氧化还原转化对于控制大多数环境中的砷化学非常重要，因此，为了可靠地预测砷如何以及为什么在环境中和环境之间移动，至关重要的是详细了解微生物-砷的相互作用。这项研究产生的信息有望对农业、矿山复垦和城市水处理中的土地和水资源管理者有价值，并将其应用于旨在操纵微生物的生物修复努力--作为环境中的相互作用，从而控制作为命运和运输的微生物。该项目将包括为两名博士研究生提供培训机会，其中包括在中国进行国际实验室轮换，以及针对美洲原住民学生的本科生研究实习。此外，PIS将与K-12教师合作，通过提供课堂课程和为期一天的显微镜练习来扩展公立和私立学校的课程，强调微生物对环境健康和功能的重要性。之前NSF资助建立的研究势头现在导致了该项目的下一代研究，旨在全面定义微生物如何在总基因表达方面对亚砷酸盐做出反应，以及如何转化为细胞生化途径的扰动。该项目的重点是一种与环境相关的细菌，使用关键基因缺陷的特定菌株，这些基因编码与亚砷酸盐检测和调节对亚砷酸盐的基因表达反应相关的功能。将被研究的微生物，根癌农杆菌菌株5A，是从世界各地受砷污染的环境中常规分离的微生物的代表。通过比较这些菌株对原始野生型生物体的亚砷酸盐反应，PI将能够定义不同的细胞反应电路，以及它们是如何不同或整合的。这项研究的框架有三个目标。目标1将使用RNA-Seq技术来表征三个主要AsIII传感系统的完整转录电路板。目的2利用代谢组学方法对同一微生物基因型的代谢物进行表征，以确定AsIII对细菌细胞代谢的全部影响，并将基因表达与实际代谢和细胞行为联系起来。目标3将使用计算方法将代谢组学和转录组数据整合到细胞系统格式中，以预测和解释代谢策略和电子命运作为AsIII暴露的函数。这项研究产生的数据将对我们了解细菌在其环境中对金属(类物质)的反应产生直接的、基础性的影响，无论环境是矿山尾矿、地下水还是土壤。

The United Nations designated 2005-2015 as an International Decade for Action: "Water for Life", with the intent of focusing attention of world governments on the declining availability of freshwater fit for human use. The severe arsenic contamination crisis in much of Asia is the most high profile example of this problem, though there are regions in the United States that also suffer from elevated arsenic in drinking water supplies. The fate, mobility, and ecotoxicology of arsenic in soil and water is highly dependent on the abiotic and biotic processes that regulate arsenic biogeochemical cycling in nature. It is now known that microbially catalyzed redox transformations are very important in controlling arsenic chemistry in most environments, and thus for reliable prediction of how and why arsenic moves within and across environments it is essential that microbe-arsenic interactions be understood in detail. The information generated from this study is expected to be of value to land and water resource managers in agriculture, mine reclamation, and municipal water treatment, finding application to bioremediation efforts aimed at manipulating microbe-As interactions in the environment and thus controlling As fate and transport. The project will include training opportunities for two Ph.D. graduate students that will include an international lab rotation in China, as well as undergraduate research internships targeting Native American students. In addition, the PIs will work with K-12 teachers to expand public and private school curricula by offering class period lectures and day-long microscopy based exercises that emphasize the importance of microorganisms to environmental health and function.TECHNICAL DESCRIPTION. Research momentum established from previous NSF funding has now led to next-generation studies in this project that aim to comprehensively define how microbes react to arsenite in terms of total gene expression and how that then translates into perturbation of cellular biochemical pathways. The project focuses on an environmentally relevant bacterium, using specific strains that are defective in key genes that encode functions associated with arsenite detecting and regulating gene expression responses to arsenite. The organism to be studied, A. tumefaciens strain5A, is representative of microorganisms routinely isolated from arsenic-contaminated environments worldwide. By comparing arsenite responses of these strains to the original wild-type organism, the PIs will be able to define the different cellular response circuits, and how they are different or integrated. There are three objectives that frame the research. Objective 1 will use RNA-Seq technology to characterize the complete transcriptional circuit board of the three major AsIII sensing systems. Objective 2 will employ metabolomics to characterize metabolite profiles for the same microbial genotypes in order to define the full effects of AsIII on bacterial cell metabolism and to link gene expression to actual metabolism and cell behavior. Objective 3 efforts will use computational methods to integrate the metabolomics and transcriptomics data into a cellular systems format for predicting and interpreting metabolic strategies and electron fates as a function of AsIII exposure. Data generated from this study will have immediate, foundational impacts on our understanding of how bacteria react to metal(loids) in their environment, whether the environment is mine tailings, groundwater or soil.