Nitrogen fixation

About: Nitrogen fixation is a research topic. Over the lifetime, 7940 publications have been published within this topic receiving 232921 citations. The topic is also known as: GO:0009399.

Nitrogen fixation by Anabaena cylindrica: III. Hydrogen-supported nitrogenase activity

Abstract: Hydrogen-supported nitrogenase activity was demonstrated in Anabaena cylindrica cultures limited for reductant. Nitrogen-fixing Anabaena cylindrica cultures sparged in the light with anaerobic gases in the presence of the photosynthesis inhibitor DCMU slowly lost their ability to reduce acetylene in the light under argon but exhibited near normal activities in the presence of 11% H2 (balance argon). The hydrogen-supported nitrogenase activity was half-saturated between 2 and 3% H2 and was strongly inhibited by oxygen (50% inhibition at about 5–6% O2). Batch cultures of Anabaena cylindrica approaching stationary growth phase (“old” cultures) lost nitrogenase-dependent hydrogen evolution almost completely. In these old cultures hydrogen relieved the inhibitory effects of DCMU and O2 on acetylene reduction. Our results suggest that heterocysts contain an uptake hydrogenase which supplies an electron transport chain to nitrogenase but which couples only poorly with the respiratory chain in heterocysts and does not function in CO2 fixation by vegetative cells.

Nitrogen Fluxes in Intensive Grassland Systems

Abstract: The relationship between inputs and outputs of nitrogen in intensive grassland systems.- The response to nitrogen fertilizer from a cut perennial ryegrass (Lolium perenne L.) pasture in the Scottish uplands relative to efficiency of fertilizer use and provision of herbage for animals.- Efficient use of fertilizer nitrogen on grass swards: effects of timing, cutting management and secondary grasses.- Nitrogen supply and the persistence of grasses.- Sources and transformations of organic nitrogen in intensively managed grassland soils.- Gaseous losses of nitrogen from grassland.- Relationships between soil mineral nitrogen content and denitrification, following application of slurry and calcium nitrate to grassland.- Losses of nitrogen from intensive grassland systems by leaching and surface runoff.- Nitrate loss through leaching and surface runoff from grassland: effects of water supply, soil type and management.

Salt-tolerant and plant growth-promoting bacteria isolated from Zn/Cd contaminated soil: identification and effect on rice under saline conditions

Abstract: The bacteria of PDMCd0501, PDMCd2007, and PDMZnCd2003 were isolated from a Zn/Cd contaminated soil. They were classified as salt-tolerant bacteria in this experiment. The bacteria had indole-3-acetic acids (IAA) production, nitrogen fixation, and phosphate solubilization, under 8% (w/v) NaCl condition. Biochemical test (API 20E) and 16S rDNA sequencing identified PDMCd2007 and PDMCd0501 as Serratia sp. and PDMZnCd2003 was Pseudomonas sp. The effect of Pseudomonas sp. PDMZnCd2003 on the germination and seedlings of Oryza sativa L.cv. RD6 was determined under a salinity of 0–16 dS/m. The salinity levels of 4–16 dS/m affected to decrease germination and seedlings of rice. Comparison between uninoculated and inoculated system, however, Pseudomonas sp. PDMZnCd2003 had a negative impact on the rice growth. This unexpected effect was a case that should be concerned and studied further before application as a plant growth-promoting bacteria (PGPB).

Nitrogen fixation at the millennium.

Abstract: 1. Nitrogen fixation - A general overview (K. Fisher, W.E. Newton). 2. Nitrogenase structure (P.M.C. Benton et al.). 3. Spectroscopy of nitrogenase (B.J. Hales). 4. The gene products of the nif regulon (L.M. Rubio, P.W. Ludden). 5. Use of short-chain alkynes to locate the nitrogenase catalytic site (S.M. Mayer et al.). 6. Regulation of Mo nitrogenases (P. Rudnick, C. Kennedy). 7. Actinorhizal symbioses (K. Pawlowski). 8. Alternative nitrogenases (B. Masepohl et al.). 9. Advances towards the mechanism of nitrogenases (R.A. Henderson). 10. A novel nitrogenase superoxide-dependent nitrogen fixation (D. Gadkari). 11. Dinitrogen chemistry (G.J. Leigh). 12. Chemical models for nitrogenase (R.L. Richards). 13. Quantification of nitrogen fixation (M.B. Peoples et al.). 14. Nitrogen fixation and agricultural practice (G.W. O'Hara et al.). 15. Nitrogen fixation in rice (P.M. Reddy et al.). Index.

Nitrogen fixation by cyanobacteria stimulates production in Baltic food webs

Abstract: Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N2 allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea.