A Cellular Systems Analysis of Microbe-Arsenic Interactions

联合国将2005年至2015年定为“生命之水”国际行动十年，旨在使世界各国政府关注适合人类使用的淡水供应量下降的问题。亚洲大部分地区的严重砷污染危机是这一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。砷在土壤和水体中的归宿、迁移和生态毒理学在很大程度上取决于自然界中调节砷地球化学循环的非生物和生物过程。现在已知，微生物催化的氧化还原转化在大多数环境中控制砷化学方面非常重要，因此为了可靠地预测砷如何以及为什么在环境中移动，必须详细了解微生物-砷相互作用。从这项研究中产生的信息预计将是有价值的土地和水资源管理人员在农业，矿山复垦，市政水处理，发现应用生物修复的努力，旨在操纵微生物作为在环境中的相互作用，从而控制作为命运和运输。该项目将包括为两名博士提供培训机会。研究生将包括在中国的国际实验室轮换，以及针对美国原住民学生的本科生研究实习。 此外，PI将与K-12教师合作，通过提供课堂讲座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。技术描述 从以前的NSF资助建立的研究势头现在已经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作出反应，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有关的细菌，使用的特定菌株在编码与亚砷酸盐相关的功能的关键基因中存在缺陷，检测和调节基因表达对亚砷酸盐的反应。 所研究的生物体A.根癌农杆菌菌株5A是从全世界砷污染环境中常规分离的微生物的代表。 通过比较这些菌株与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回路，以及它们是如何不同或整合的。 有三个目标，框架的研究。 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。 目标2将采用代谢组学来表征相同微生物基因型的代谢产物谱，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的努力将使用计算方法，将代谢组学和转录组学数据整合到细胞系统格式中，用于预测和解释作为AsIII暴露函数的代谢策略和电子命运。 这项研究产生的数据将对我们了解细菌如何对环境中的金属（loids）反应产生直接的基础性影响，无论环境是尾矿，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.