MICROBIAL METABOLISMS OF REDUCED PHOSPHOROUS COMPOUNDS

拟议研究的长期目标是鉴定和分子，遗传和生物化学特性的微生物代谢过程中参与氧化还原反应的磷化合物。 这些反应很少被研究，代表了这个重要元素的生物化学的新方面，它在所有生物体的代谢中起着核心作用。 已知还原磷化合物的产生和消耗发生在许多生物体中，包括人类。 这些化合物的代谢对于这些化合物在它们被发现的生物体中的天然作用以及对于广泛用于工业、农业和军事目的的人造还原磷化合物的毒性和环境持久性具有重要性。 此外，磷是许多生态系统中的限制性营养素。 磷的氧化还原反应可能在这种必需营养素的生物利用度和全球循环中发挥重要作用。 为了进一步了解这些过程，我们已经分离出一些微生物，它们具有涉及P化合物的氧化还原化学的新的生化途径。 这里提出的实验涉及在遗传和生物化学水平上鉴定和表征这些反应。 这些实验的具体目标是：1）通过标准生物化学方法纯化和表征施氏假单胞菌中参与P氧化途径的两种新酶，2）表征14个基因的功能和遗传调控（至少）参与这种斯氏疟原虫途径的突变分析和转录报告基因研究，3）分子，遗传，大肠杆菌氧化亚磷酸盐的新途径的生物化学表征，4）新细菌分离物厌氧次磷酸盐氧化的新途径的分子遗传学表征，和5）具有涉及P氧化还原反应的其他新代谢途径的生物体的分离和表征。

The long-term objective of the proposed research is the identification and molecular, genetic and biochemical characterization of microbial metabolic processes involved in oxidation-reduction reactions of phosphorus compounds. These reactions have been little studied and represent novel aspects of the biochemistry of this important element, which plays a central role in the metabolism of all living organisms. The production and consumption of reduced P compounds are known to occur in many organisms, including humans. The metabolism of these compounds has importance with respect to the natural roles of these compounds in the organisms where they are found, and with respect to the toxicity and environmental persistence of man-made reduced P compounds, which are widely used for industrial, agricultural and military purposes. Further, phosphorus is the limiting nutrient in many ecosystems. Redox reactions of phosphorus may play an important role in the bioavailability and global cycling of this required nutrient. To further our understanding of these processes we have isolated a number of microorganisms that possess novel biochemical pathways involving redox chemistry of P compounds. The experiments proposed here involve identification and characterization of these reactions at the genetic and biochemical levels. The specific goals of these experiments are: 1) purification and characterization by standard biochemical approaches of two novel enzymes involved in a P oxidation pathway in Pseudomonas stutzeri, 2) characterization of the functions and genetic regulation of the 14 genes (at least) involved in this P. stutzeri pathway using mutant analysis and transcriptional reporter gene studies, 3) molecular, genetic, and biochemical characterization of a novel pathway for oxidation of phosphite by Escherichia coli, 4) molecular genetic characterization of a novel pathway for anaerobic hypophosphite oxidation by a new bacterial isolate, and 5) isolation and characterization of organisms that possess other novel metabolic pathways involving P redox reactions.