Functional and Taxonomic Diversity of the Nitrogen Cycling Guild in the Sargasso Sea Metagenomes
Germán Bonilla-Rosso, Luis Eguiarte and Valeria Souza
from: Metagenomics of the Microbial Nitrogen Cycle: Theory, Methods and Applications (Edited by: Diana Marco). Caister Academic Press, U.K. (2014)
The number and quality of available metagenomes from the oligotrophic Sargasso Sea provides an unprecedented opportunity to study taxonomic and functional diversity in its microbial communities. Here, we dissect the diversity within seven functional guilds involved in nitrogen cycling, and contextualize them with overall taxonomic diversity. Our results reveal a large preference for fixed nitrogen regeneration and reutilization, as opposed to novel incorporation of inorganic nitrogen. An overall relationship was found between taxonomic and functional richness, but not evenness. All the metabolic pathways analized were present in all sampling sites and all size fractions, suggesting a similarity in the ecological niches available for these guilds. Nevertheless, we found significant differences in the phylogenetic composition and community structure within these guilds. The numerical dominance of versatile oligotrophs that can use a wide variety of simple molecules is evident, while the guild inspection revealed the presence of a relatively abundant, uncharacterised or uncultured group of organisms specialized in the degradation of complex organic matter. The presence of proteorhodopsins in many of these organisms suggests the existence of an unexplored link between nitrogen cycling and phototrophy read more ...