Norton - Nitrogen Cycle Enzymes Abstract

Norton - Research Abstract

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Functional And Molecular Diversity In Nitrogen Cycle Enzymes Under Contrasting Agricultural Management Systems

Funded USDA –NIFA 2011-2015
The management of organic nitrogen (N) sources and improvements in N use efficiency are key determinants of agroecosystem sustainability. Availability of N from organic sources is the outcome of diverse enzymatic processes comprising N mineralization, immobilization and nitrification. Molecular tools are needed to link these enzymatic functions to the responsible microbial community in soils. Novel methods for the examination of microorganisms responsible for N turnover will be developed and will enable description of the microbial community responsive to contrasting N sources and quantities. Our goal is to describe functional diversity in the root-zone of microbial communities responsible for selected N transformations in agroecosystems under contrasting nitrogen management. We will extract microbial DNA and mRNA from soil sampled from existing experimental systems in Utah and Georgia. Functional diversity of the genes encoding enzymes will be examined using molecular tools including PCR and clone libraries, 454 sequencing of tagged clone libraries and real-time PCR in association with measurements of N transformation rates and enzyme kinetics. Using functionally targeted metagenomic surveys of soil DNA, we will recover and characterize novel bacterial and fungal genes encoding key enzymatic functions in N transformations. The role of bacterial and archaeal ammonia oxidizers in soil nitrification will be further delineated. Knowledge of diversity in the genes encoding enzymes responsible for N cycling will strengthen our understanding of microbial controls on N availability to plants. Improved understanding of microbial N cycling will aid in the development of agricultural systems with enhanced N cycling efficiency and promote food security.

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