CAREER: Enzyme Expression in Microbial Communities Oxidizing Emerging Water Contaminants: An Integrated Research and Education Plan

CBET-1255021加州大学洛杉矶分校Shaly Mahendra该项目将研究微生物如何降解和解毒危险化学物质，这些化学物质目前在供水中存在着一种新的、但不受监管的存在。产生单加氧酶的细菌是唯一能够生物降解各种顽固化合物的细菌，如氯化溶剂、石油碳氢化合物、杀虫剂和醚。这些酶含有过渡金属，以促进生化氧化还原反应中的电子转移，它们的效率可能会因特定金属的可用性而不同数量级。1，4-二恶烷是一种可能的致癌物质，其生物降解由单加氧酶介导，将作为本研究中的新出现污染物的模型。1，4-二氧六环是氯化溶剂的稳定剂，是纺织纤维加工中的润湿剂，也是几种个人护理产品的副产品。在混合废物和污染场地中，铁、钴、铜、镍、锌和其他有机物与1，4-二恶烷共存，会影响单加氧酶和1，4-二恶烷的生物降解率。在这项研究中收集的数据将展示金属和地球化学条件对液体培养中生长的细菌以及生长在沙子或碳基表面的生物膜对1，4-二恶烷生物降解的影响。将设计新的比色和遗传工具，以快速估计不同类型的生长和环境条件下相关的生物降解酶和金属抗性酶的活性。将使用基因芯片和强大的DNA测序方法来评估活跃在1，4-二恶烷生物降解中的微生物群落组成的变化。传统的清理技术昂贵，消耗资源和能源，或者将污染从一个地方转移到另一个地方。对于从土壤、沉积物、地下水和废水中去除新出现的污染物，生物修复可能是一个技术上和经济上可行的选择。该项目将提供有关环境污染物的去向和转化的关键数据，这些污染物最近已落入监管机构的审查之下。这项研究的结果将被PI与环境工程专业人员合作，用于设计工业和军事废物流的生物修复和监测系统。研究工作将与在初中、高中、本科生和研究生阶段指导不同背景的学生相结合。除了出版物和在科学会议上的陈述外，这些发现还将与环境工程和微生物学课程相结合。

CBET-1255021Shaily MahendraUniversity of California, Los AngelesThis project will investigate how microbes can degrade and detoxify hazardous chemicals which have an emerging, yet currently unregulated, presence in water supplies. Bacteria that produce monooxygenase enzymes are uniquely capable of biodegrading a variety of recalcitrant compounds, such as chlorinated solvents, petroleum hydrocarbons, pesticides, and ethers. These enzymes contain transition metals to facilitate transferring electrons in biochemical redox reactions, and their efficiency can vary over orders of magnitude depending upon the availability of specific metals. 1,4-Dioxane, a probable carcinogen, whose biodegradation is mediated by monooxygenases, will be used as a model emerging contaminant in this study. 1,4-Dioxane is a stabilizer of chlorinated solvents, a wetting agent in the processing of textile fibers, and a byproduct in several personal care products. In mixed wastes and contaminated sites, metals such as iron, cobalt, copper, nickel, zinc, and other organics coexist with 1,4-dioxane and will influence the monooxygenase enzymes as well as 1,4-dioxane biodegradation rates. Data collected in this research will demonstrate the effects of metals and geochemical conditions on 1,4-dioxane biodegradation by bacteria growing in liquid cultures as well as biofilms growing on sand or carbon-based surfaces. Novel colorimetric and genetic tools will be designed to rapidly estimate the activities of relevant biodegradative and metal-resistant enzymes under different types of growth and environmental conditions. Changes in composition of microbial communities actively engaged in 1,4-dioxane biodegradation will be assessed by using gene chips and powerful DNA sequencing methods. Conventional clean-up technologies are expensive, consume resources and energy, or move the pollution from one place to another. Bioremediation could be a technically and financially viable option for removing emerging contaminants from soil, sediments, groundwater, and wastewater. This project will provide critical data on fate and transformations of environmental contaminants that have recently fallen under the scrutiny of regulatory agencies. The results from this study will be leveraged by the PI, in collaboration with environmental engineering professionals, to design bioremediation and monitoring systems for industrial and military waste streams. Research efforts will be coupled with mentoring students of diverse backgrounds at the middle school, high school, undergraduate, and graduate levels. In addition to publications and presentations at scientific meetings, the findings will be integrated with curricula of environmental engineering and microbiology courses.