Marine environment fixed nitrogen

Diazotrophs Nitrogen-fixing bacteria. In the marine environment, some nitrogen fixers live as symbionts in phytoplankton, particularly diatoms. 

Table 10.6 Nitrogen-fixing bacteria isolated from marine environments.

Nitrogen-Fixing and Nitrifying Symbioses IN THE Marine Environment... 

Nitrogen fixation in the marine environment occurs in benthic (sediments and microbial mats) and pelagic environments, and in salt marsh soils (see Carpenter and Capone, Chapter 4, this volume). Since very diverse microorganisms that span the Bacteria and Archaea domains of life can fix nitrogen, it is often difficult to ascertain which organisms are responsible for observed nitrogen fixation rates. Our discussion of the application of molecular approaches to the study of marine nitrogen fixation is brief because it has been reviewed extensively elsewhere (Carpenter and Capone, Chapter 4, this volume Foster and O MuUan Chapter 27, this volume Scanlan and Post, Chapter 24, this volume Paerl and Zehr, 2000 Zehr and Ward, 2002 Zehr et al., 2003). 

Heterotrophic respiration fueled by the rain of organic matter from the surface ocean is ubiquitous in marine sediments. Its rate determines one of the important characteristics of the sedimentary environment the depth of redox horizons below the sediment-water interface. Heterotrophic respiration is the process by which carbon and nutrients are returned to the water column it is important in the marine fixed nitrogen and sulfur cycles and the accumulation of metabolic products sets the conditions for the removal of phosphorus from the oceans in authigenic minerals. A great deal of effort has been directed toward quantifying the rates, pathways, and effects of metabolism in sediments. 

Bebout, B.M., Fitzpatrick, M.W., and Paerl, H.W. (1993) Identification of the sources of energy for nitrogen fixation and physiological characterization of nitrogen-fixing members of a marine microbial mat community. Appl. Environ. Microbiol. 59, 1495-1503. 

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