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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.


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Journal ArticleDOI
TL;DR: The calculated areal N2 fixation rate (15 m mol Nm 22 d21) was small compared with estimates from other regions of the Pacific; however, the estimated fixation rate was similar to other published results, suggesting that processes other than cellular growth rate may determine the abundance of unicellular diazotrophs.
Abstract: N2 fixation has been understudied in marine environments outside of the subtropical and tropical oceans and where water temperatures are typically below 20–25uC. We identified nifH phylotypes and measured N2 fixation rates under ambient conditions (maximum of 19uC) in water collected 750 km off the coast of California in oligotrophic waters of the North Pacific Ocean (34uN, 129uW). Near-surface N2 fixation rates averaged 0.25 6 0.05 nmol N L21 d21 for 24 incubation bottles. Despite low ambient concentrations of iron (,0.1 nmol L21) and phosphorus (,0.3 mmol L21), N2 fixation rates were unaffected by iron and phosphorus amendments. Using reverse transcription–quantitative polymerase chain reaction (RT-QPCR) methodology, we estimated transcript abundance and patterns of expression for several unicellular diazotrophs, including the group A phylotype, which showed the highest daily mRNA abundances. The N2-fixing assemblage extended to 60–80 m depth, well below the seasonal thermocline (40 m). The calculated areal N2 fixation rate (15 m mol Nm 22 d21) was small compared with estimates from other regions of the Pacific; however, the estimated fixation rate was similar to other published results, suggesting that processes other than cellular growth rate may determine the abundance of unicellular diazotrophs. Despite the low N2 fixation rates, the new nitrogen added to the euphotic zone by N2 fixation could account for at least 10% of new production during the study period.

138 citations

Journal ArticleDOI
01 Nov 1984-Nature
TL;DR: The discovery of a nitrogen-fixing archaebacterium has important implications for studies on the evolution of nitrogenase, and the fact that M. thermolithotrophicus nitrogenase is active at 64 °C suggests that a novel enzyme is involved.
Abstract: Methanogenic bacteria are known to use NH+4 as a nitrogen source for growth1. Previous work with an impure methanogenic culture suggested that a methanogen might fix atmospheric dinitrogen as a nitrogen source2, but no further work on this phenomenon has been documented. We have now examined the use of N2 by Methanococcus thermolithotrophicus and find that the organism can grow well, with multiple transfers, in medium having N2 as the source of nitrogen. Control cultures without N2 and containing less than 0.1 mM NH+4 do not grow. Growth yields with N2 are on the average one-third those with NH+4, suggesting that, as in other nitrogen-fixing organisms, this bacterium requires a large amount of ATP for the reduction to occur. After growing in NH+4-containing medium, a long lag is observed before growth begins with N2 as the nitrogen source; the NH+4 levels must be very low for growth to begin. Cells grown in N2-fixing conditions reduce acetylene to ethylene. The discovery of a nitrogen-fixing archaebacterium has important implications for studies on the evolution of nitrogenase, and the fact that M. thermolithotrophicus nitrogenase is active at 64 °C suggests that a novel enzyme is involved.

138 citations

Journal ArticleDOI
TL;DR: The association of G. diazotrophicus with sugarcane, other crop plants and with various hosts is discussed and the plant-growth-promoting traits identified in this group of bacteria, including N2 fixation, phytohormone synthesis, P and Zn solubilization and biocontrol, are analysed.
Abstract: Gluconacetobacter diazotrophicus has a long-standing history of bacterial-plant interrelationship as a symbiotic endophyte capable of fixing atmospheric nitrogen. In low nitrogen fertilized sugarcane fields it plays a significant role and its occurrence was realised in most of the sugarcane growing countries. In this mini review, the association of G. diazotrophicus with sugarcane, other crop plants and with various hosts is discussed. The factors affecting survival in the rhizosphere and the putative soil mode of transmission are emphasized. In addition, other N2-fixing Acetobacteraceae members, including Gluconacetobacter azotocaptans, Gluconacetobacter johannae and Swaminathania salitolerans, occurring in coffee, corn and rice plants are also covered. Lastly, the plant-growth-promoting traits identified in this group of bacteria, including N2 fixation, phytohormone synthesis, P and Zn solubilization and biocontrol, are analysed.

138 citations

Journal ArticleDOI
Roy S. Tubb1
11 Oct 1974-Nature
TL;DR: Glutamine synthetase seems to act as a positive control element for nitrogenase synthesis in Klebsiella in a way similar to that already proposed for histidase synthesis as well as providing answers to many of the problems in establishing nitrogen fixation in non-leguminous plants.
Abstract: Glutamine synthetase seems to act as a positive control element for nitrogenase synthesis in a way similar to that already proposed for histidase synthesis in Klebsiella. Studies along lines opened up by these findings may provide answers to many of the problems in establishing nitrogen fixation in non-leguminous plants.

138 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023390
2022831
2021263
2020240
2019250
2018261