in calcareous soils with high calcium carbonate contents and ph, the growth and development of plant might undergo nutritional disorders. the process of biological nitrogen fixation in legumes cultivated and plant growth in these soils could be limite. the use of acid-producing materials like sulfur and a reduction in soil ph improves plant growth and increase the biological nitrogen fixation. ...

The filamentous non-heterocystous cyanobacterium Plectonema boryanum fixes dinitrogen at a high rate during microaerobic growth in continuous illumination by temporal separation of oxygen-evolving photosynthesis and oxygen-sensitive dinitrogen fixation. The onset of nitrogen fixation is preceded by a depression in photosynthesis that establishes a sufficiently low level of dissolved oxygen in t...

In biological nitrogen fixation the key intermediate compound, defined as the end product of the fixation reaction and the initial reactant of assimilation, is believed to be either ammonia or hydroxylamine. Burris and Wilson (1945) noted that these two possibilities need not be mutually exclusive but may occur simultaneously, depending on the concentrations of the carbon compounds serving as a...

We have used genetic methods in Methanococcus maripaludis to study nitrogen metabolism and its regulation. We present evidence for a "nitrogen regulon" in Methanococcus and Methanobacterium species containing genes of nitrogen metabolism that are regulated coordinately at the transcriptional level via a common repressor binding site sequence, or operator. The implied mechanism for regulation re...

INTRODUCTION Industrial nitrogen fixation plays an important role in sustaining approximately 40% of the Earth’s population through generation of synthetic fertilizers. Annually, ca. 500 million tons of anhydrous ammonia, ammonium nitrate, and urea are produced through the Haber-Bosch process, which requires harsh conditions (200 atm, 450-500C) and affords low yields 10-20%. It has been estimat...

Ammonia is generally conceded to be the "key intermediate" in biological nitrogen fixation-that is, the compound which reacts to form the first stable organic compound, glutamic acid (Wilson and Burris, 1953). However, there is virtually no information concerning the reactions functioning in the conversion of N2 to ammonia. Reproducible nitrogen fixation by a cell-free preparation from bacteria...

Dinitrogen (N2) fixation rates were measured during early spring across the different provinces of Mediterranean Sea surface waters. N2 fixation rates, measured using N2 enriched seawater, were lowest in the eastern basin and increased westward with a maximum at the Strait of Gibraltar (0.10 to 2.35 nmol N L−1 d−1, respectively). These rates were 3–7 fold higher than N2 fixation rates measured ...

Unicellular cyanobacteria have recently been recognized for their contributions to nitrogen fixation in marine environments, a function previously thought to be filled mainly by filamentous cyanobacteria such as Trichodesmium. To begin a systems level analysis of the physiology of the unicellular N(2)-fixing microbes, we have sequenced to completion the genome of Cyanothece sp. ATCC 51142, the ...

The Trichodesmium erythraeum is a common colonial marine cyanobacterium in tropical and subtropical oceans. Several authors have reported its importance for the fixation of both atmospheric C and N (CAPONE; CARPENTER, 1982; ZEHR et al., 2001; LUGOMELA et al., 2002; CAPONE et al., 2005). According to Carpenter and Romans (1991), nitrogen fixation by Trichodesmium cells represents an important in...