Bacteria nitrogen fixers

Oxygenic photosynthetic bacteria include the nitrogen fixer Trtchodesmtum and the cyanobacteria Synechococcus and Prochlorococcus. The latter represent a major fraction of the microbial biomass in the ocean and are probably the most abimdant primary producers in the ocean. They were not discovered until the late 1980s, probably because of their small size as they are members of the picoplankton. These cyanobacteria are photosynthetic. They use bacteriochlorophyll a and plastocyanin, a blue Cu-based pigment, for light harvesting. 

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

Azad, H.R., Davis, J.R., Schnathorst, W.C., Kado, C.I. Influence of Verticillium wilt resistant and susceptible potato genotypes on populations of antagonistic rhizosphere and rhizoplane bacteria and free nitrogen fixers. Appl Microbiol Biotechnol 1987 26 99-104. 

In aquatic habitats, cyanobacteria are the principal nitrogen fixers. Rates of nitrogen fixation by cyanobacteria are generally one or two orders of magnitude higher than those by free-living, nonphotosynthetic soil bacteria. Under favorable conditions, cyanobacteria may fix up to 1600 kg of N/ha/year in a rice paddy. 

Similar c-type cytochromes are involved in many kinds of energy metabolism in bacteria, such as phototrophes, methylotrophes, sulfate reducers, nitrogen-fixers, and denitrifiers. For example, in the anaerobic electron chain of the denitrification system in Gram-negative bacteria, c-type cytochromes transfer electrons from the cyt bc complex to cytochrome cdy nitrite reductase, N2O... 

Anaerobic bacteria. The chief anaerobic nitrogen fixers found in soils belong to the genus Clostridium. They are widespread and present in much larger numbers than are Azotobacter. Since they are anaerobic, they are commonly present largely as spores in the... 

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