MSB: Insights Into Mutualistic Interactions Between Free-Living, Pleomorphic Spirochetes (FLiPS) and Obligate Dechlorinators (Dehalococcoides)

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。土壤、沉积物和地下环境中蕴藏着极其多样化的微生物，一个主要的研究目标是更好地了解这些复杂的系统是如何进化、运行和响应环境变化的。侧重于单个细菌种群的简化论方法提供了大量有价值的信息，通常是在简化的条件下，但为了真正了解复杂的微生物群落是如何运作的，必须探索居住在同一环境中的不同种群之间的相互作用和相互依存关系。这一提议的前提是许多细菌与邻近生物进行未知的相互作用，并且这些物种间的联系可以使用微生物学和基因组使能的方法来表征。脱卤球菌属和自由生活的多形性螺旋体(Flips)是天然河流沉积物和含水层微生物群落的成员。脱卤球菌属是高度专门化的细菌，通过从包括优先污染物在内的许多碳氢化合物中去除卤素取代基来获得生长所需的能量。这个过程被称为有机卤化物呼吸，当细菌呼吸卤代烃(就像我们呼吸空气一样)时，污染物被解毒。脱卤球菌属细菌在分离时生长非常差，但在混合培养中表现强劲，当存在翻转时。相反，Flips受益于脱卤球菌属，该项目的一个主要目标是探索这些微生物相互作用的生物分子基础。该项目将在基础、分子水平上描述尚未探索的微生物-微生物相互作用(共生)的特征，并阐明导致明显不同微生物种群之间有益互动的进化机制。这项研究项目将对微生物-微生物相互作用如何发展、运行和持续，同时影响群落的特定功能(例如，卤代烃的解毒)产生新的理解。该项目不仅将增进对嗜盐球菌和螺旋体生物学的了解，还将进一步提高我们预测微生物群落如何运作和对扰动做出反应的能力。波多黎各大学的两名博士生和三名暑期本科生将参与这项研究工作。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Soil, sediment and subsurface environments harbor a tremendous diversity of microbes, and a major research goal is to better understand how such complex systems evolve, function, and respond to environmental changes. The reductionist approaches that focused on individual bacterial populations provided a wealth of valuable information, usually under simplified conditions, but to truly understand how complex microbial communities function, the interactions and interdependencies between different populations inhabiting the same environment must be explored. The premise of this proposal is that many bacteria engage in unknown interactions with neighboring organisms, and that these interspecies links can be characterized using microbiological and genome-enabled approaches. Dehalococcoides and free-living, pleomorphic spirochetes (FLiPS) are members of natural river sediment and aquifer microbial communities. Dehalococcoides are highly specialized bacteria that gain energy for growth by removing halogen substituents from many hydrocarbons, including priority pollutants. This process is called organohalide respiration, and as the bacteria breathe halogenated hydrocarbons (just like we breathe air), the contaminants are detoxified. Dehalococcoides bacteria grow very poorly in isolation but perform robustly in mixed cultures when FLiPS are present. Conversely, FLiPS benefit from Dehalococcoides, and a major goal of the project is to explore the biomolecular basis of these microbe-microbe interactions. This project will characterize unexplored microbe-microbe interactions (symbiosis) at the fundamental, molecular level and shed light on the evolutionary mechanisms that lead to beneficial interactions between distinctly different microbial populations. This research project will generate new understanding on how microbe-microbe interactions develop, operate, and persist, while affecting specific functions of the community (e.g., detoxification of halogenated hydrocarbons). This project will not only advance knowledge of Dehalococcoides and spirochete biology, but will further improve our predictive ability how microbial communities function and respond to perturbations. Two doctoral students and three summer undergraduate students from the University of Puerto Rico will engage in this research effort.