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Denitrifying bacterial community composition changes associated with stages of denitrification in oxygen minimum zones

DRS at CSIR-National Institute of Oceanography

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Title Denitrifying bacterial community composition changes associated with stages of denitrification in oxygen minimum zones
 
Creator Jayakumar, D.A.
O'Mullan, G.D.
Naqvi, S.W.A.
Ward, B.B.
 
Subject denitrification
community composition
oxygen minimum layer
nitrogen cycle
biogeochemical cycle
 
Description Denitrification in the ocean is a major sink for fixed nitrogen in the global N budget, but the process is geographically restricted to a few oceanic regions, including three oceanic oxygen minimum zones (OMZ) and hemipelagic sediments worldwide. The diversity and community composition of microbes responsible for denitrification in the OMZ using polymerase chain reaction, sequence and fragment analysis of clone libraries of the signature genes (nirK and nirS) that encode the enzyme nitrite reductase, responsible for key denitrification transformation steps is described. It is shown that denitrifying assemblages vary in space and time and exhibit striking changes in diversity associated with the progression of denitrification from initial anoxia through nitrate depletion. The initial denitrifying assemblage is highly diverse, but succession on the scale of 3-12 days leads to a much less diverse assemblage and dominance by one or a few phylotypes. This progression occurs in the natural environment as well as in enclosed incubations. The emergence of dominants from a vast reservoir of rare types has implications for the maintenance of diversity of the microbial population and suggests that a small number of microbial dominants may be responsible for the greatest rates of transformations involving nitrous oxide and global fixed nitrogen loss. Denitrifying blooms, driven by a few types responding to episodic environmental changes and distributed unevenly in time and space, are consistent with the sampling effect model of diversity-function relationships. Canonical denitrification thus appears to have important parallels with both primary production and nitrogen fixation, which are typically dominated by regionally and temporally restricted blooms that account for a disproportionate share of these processes worldwide.
 
Date 2009-12-21T06:44:06Z
2009-12-21T06:44:06Z
2009
 
Type Journal Article
 
Identifier Microbial Ecology, vol.58(2); 350-362
http://drs.nio.org/drs/handle/2264/3488
 
Language en
 
Rights An edited version of this paper was published by Springer. This paper is for R & D pupose and Copyright [2009] Springer
 
Publisher Springer