Novel Aspects of Phosphorus Metabolism in Thermophilic Cyanobacteria

磷是遗传信息、能量代谢、结构和细胞信号分子的关键组成部分，但在几个重要的生态系统中往往是一种限制性营养物质。因此，了解不同来源的磷(如磷酸盐和磷酸盐)是如何在环境中获得和再循环的是至关重要的。原核生物，包括蓝藻，在许多环境中对磷(P)、碳(C)和氮(N)的生物地球化学循环起着重要作用。关于陆地生物圈中生物可利用磷化合物的总水平知之甚少，不同生态系统之间可能存在很大差异。此外，磷酸盐(具有稳定的C-P键，因此不易降解)的合成和释放到环境中是相当重要的，因为它们在各种工业中广泛使用。因此，许多陆地和水生生态系统受到污染。因为磷是一种关键的营养物质，细菌已经进化出复杂的方法来感知和清除可用的磷来源，包括磷酸盐。从温泉垫中分离的极端嗜磷蓝藻具有复杂的磷获取和代谢回路，并具有代谢磷酸盐的能力。这些与环境有关的蓝藻将被用来剖析和探索关于磷/磷酸盐利用的调节及其与环境中的碳代谢和循环的联系的问题。将使用文字记录分析和生化分析来确定不同磷源利用的异同。在规定的条件和垫子的环境参数下，将测定分离株中各种磷物种的水平。这些蓝藻的靶向突变体使详细的遗传分析成为可能。将特定条件下的反应与在环境中直接测量的反应相关联，将有助于了解微生物群落如何对环境中的磷水平做出反应并适应环境中的磷水平。相反，各种人为有机磷化合物(杀虫剂、除草剂等)也可能是工业废水中的主要污染物，并导致水体富营养化。因此，近年来，有害和难以管理的蓝藻和藻类水华有所增加。关于蓝藻如何有效地获取和代谢不同有机磷来源的见解可能广泛适用于其他光合作用微生物，特别是海洋中的微生物。这些发现在生物修复研究中也可能有一定的意义，因为有迹象表明，磷酸盐利用基因可以在不同谱系之间横向转移。在开展这一研究项目的过程中，将对本科生、研究生和博士后研究员进行培训。卡内基学院位于斯坦福大学校园内，致力于研究，并提供出色的跨学科研究培训和参加人数众多的暑期实习生计划。与圣何塞州立大学和奥克兰米尔斯学院(一所历史悠久而久负盛名的女子学院)建立的紧密联系，将使其能够培训通常在科学方面代表性较低的学生。最后，由于这项研究涉及黄石国家公园的微生物，研究人员将与公园当局合作，为他们广泛使用的推广计划做出贡献。

Phosphorus is a key component of genetic information, energy metabolism, structural and cell signaling molecules, but is often a limiting nutrient in several important ecosystems. Thus an understanding of how different sources of P (such as phosphates and phosphonates) are acquired and recycled in the environment is of critical importance. Prokaryotes, including cyanobacteria, contribute importantly to the biogeochemical cycling of phosphorus (P), carbon (C) and nitrogen (N) in many environments. Little is known about the total levels of bioavailable P compounds in the terrestrial biosphere and there can be wide variation in different ecosystems. Furthermore, the synthesis and release of phosphonates (which have a stable C-P bond and are therefore not easily degraded) into the environment is quite significant because of their extensive use in various industries. As a consequence many terrestrial and aquatic ecosystems are contaminated. Because P is a key nutrient, bacteria have evolved sophisticated ways to sense and scavenge available sources of P, including phosphonates. Extremophilic cyanobacterial isolates from hot spring mats have a complex P acquisition and metabolism circuitry and also have the capacity to metabolize phosphonates. These environmentally relevant cyanobacteria will be used to dissect and explore questions regarding the regulation of phosphorus/phosphonate utilization and its connection to carbon metabolism and cycling in the environment. Similarities and differences in the utilization of various phosphorus sources using transcript analysis and biochemical assays will be defined. Levels of various P species in the isolates under defined conditions and environmental parameters in the mats will be determined. Targeted mutants of these cyanobacteria has made detailed genetic analysis feasible. Correlating responses under defined conditions and those measured directly in the environment will allow for an understanding of how microbial communities respond and acclimate to phosphorus levels in the environment.Broader ImpactsPhosphorus is often a nutrient that limits growth in marine and terrestrial environments. Conversely, various anthropogenic organophosphorus compounds (insecticides, herbicides etc.) can also be major contaminants in industrial effluents and contribute to the eutrophication of water bodies. Consequently, harmful and unmanageable cyanobacterial and algal blooms have increased in recent years. The insights gained about how cyanobacteria effectively access and metabolize different organophosphorus sources maybe broadly applicable to other photosynthetic microbes, particularly those in the oceans. These findings may also be of some significance in bioremediation studies since there is an indication that phosphonate utilization genes can be transferred laterally across lineages. In the process of developing this research program, undergraduates, graduate students and post-doctoral fellows will be trained. The Carnegie Institution which is located on the campus of Stanford University is dedicated to research and offers excellent training in interdisciplinary research and a well-attended summer intern program. Strong ties with San Jose State University which has a large and diverse student body and with Mills College, Oakland, a historical and well-established women's college, will allow for training of students typically under-represented in science. Finally, since this research involves microbes at Yellowstone National Park, researchers will work with Park authorities to contribute to their extensive and widely used outreach program.