MICROBIAL METABOLISMS OF REDUCED PHOSPHOROUS COMPOUNDS

该研究的长期目标是鉴定和参与磷化合物氧化还原反应的微生物代谢过程的分子、遗传和生化特征。这些反应很少被研究，代表了这一重要元素的生物化学的新方面，它在所有生物体的新陈代谢中起着核心作用。已知在包括人类在内的许多生物体中都会产生和消耗还原性磷化合物。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自然作用，以及对广泛用于工业、农业和军事目的的人造还原价磷化合物的毒性和环境持久性具有重要意义。此外，磷是许多生态系统中的限制性营养物质。磷的氧化还原反应可能在这种必需营养物的生物利用度和全球循环中起重要作用。为了进一步了解这些过程，我们分离了一些具有涉及P化合物氧化还原化学的新型生化途径的微生物。这里提出的实验包括在遗传和生化水平上对这些反应进行鉴定和表征。这些实验的具体目标是：1)通过标准生化方法纯化和鉴定了两种新型的与斯图茨利假单胞菌P氧化途径相关的酶；2)利用突变体分析和转录报告基因研究鉴定了至少14个与斯图茨利假单胞菌P氧化途径相关的基因的功能和遗传调控；3)大肠杆菌氧化亚磷酸酯的新途径的分子、遗传和生化鉴定。4)一种新的细菌分离物对厌氧次亚磷酸盐氧化新途径的分子遗传学表征；5)具有其他涉及P氧化还原反应的新代谢途径的生物的分离和表征。

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.