Ecophysiology and Genomics of N-cycling Microbes in the Environment

Abstract

The most prominent element of the Earth, nitrogen, exists in various forms owing to its wide oxidation state of −3 to +5, in the form of NH3, NH4+, NO, NO2, N2O, HNO3, HONO, PAN and many other organic N compounds. It is a primary component of life’s existence as it is involved in protein synthesis, the building blocks of organisms, as well as a tremendous number of protein-regulated biological activities. The nitrogen cycle maintains balance and the required recompense of nitrogen in the biosphere. Microbes enriched with various cellular and molecular elements contribute to the accomplishment of biological nitrogen by ammonia fixation, converting atmospheric nitrogen to the ammonia form so that plants or other producers can assimilate it, as well as nitrification and denitrification to release it from the biosphere as nitrogen gas. Phylogeny analysis, an essential biological tool, can express the comparison of genetic, individual, population, and species information in terms of morphology, behavioural, or molecular data. Phylogeny analysis estimates historic relationships between genes or species and describes these relationships in a branching diagram, a phylogenetic tree. This chapter discusses the essential concepts of groups of microbes (N-fixer, nitrifier and denitrifier), involved in the N-cycle, and their functions (transformation of nitrogen). Intra and inter-specific interactions among N-cycle microorganisms and their role in the global N-cycle are investigated to expand the understanding of nitrogen–microbe interactions using an omics approach.