In Klebsiella pneumoniae, the nif specific transcriptional activator NifA is inhibited by NifL in response to molecular oxygen and ammonium. Here, we demonstrate complex formation between NifL and NifA (approximately 1 : 1 ratio), when synthesized in the presence of oxygen and/or ammonium. Under simultaneous oxygen- and nitrogen-limitation, significant but fewer NifL-NifA complexes (approximate...

The impact of light and nutrients (such as silicate and iron) availability on nitrogen uptake and primary production vary seasonally and regionally in the Southern Ocean. The seasonal cycle of nitrogen uptake by phytoplankton in the Southern Ocean is not fully resolved over an annual scale due to the lack of winter in situ measurements. In this study, nitrate and ammonium uptake rates were meas...

Chitinolytic and glucanolytic fungal cell wall-degrading enzymes have been suggested to be primary determinants of biocontrol by Trichoderma spp. We examined the effects of ammonium, glucose, chitin, and chito-oligomers on transcription of specific genes and secretion of fungal cell wall-degrading enzymes. The genes ech42, nag1, and gluc78 were examined, as were the enzymes they encode (endochi...

Anaerobic ammonium oxidation (anammox) involves the microbiological oxidation of ammonium with nitrite as the electron acceptor and dinitrogen gas as the main product. The Scalindua species, an anammox genus that dominates natural habitats, plays an important role in catalysing the loss of nitrogen from marine environments. Until now, a few Scalindua species have been reported to be enriched fr...

Nitrogen (N) in livestock food sources that does not end up in a product (e.g. milk or eggs) or that does not get incorporated in body tissue is excreted by the animal. Nitrogen in the urine is in the form of urea which can rapidly hydrolyse to form ammonium carbonate. The decomposition of ammonium carbonate frees up ammonium ions that can volatilise as gaseous ammonia (NH3). Hydrolysis of urea...

Ammonium transporters (AMTs) play a role in the uptake of ammonium, the form in which nitrogen is preferentially absorbed by plants. Vigna subterranea (VsAMT1) and Solanum tuberosum (StAMT1) AMT1s were characterized using molecular biology and bioinformatics methods. AMT1-specific primers were designed and used to amplify the AMT1 internal regions. Nucleotide sequencing, alignment and phylogene...

soil compaction as a global problem and a multi-dimensional and complex process involving the interaction of climate, soil mashyn- plant- known to have a significant economic and environmental impacts and to sustainable agriculture is an intractable problem.for in order to assess compaction effect on nitrogen mineralization process in soil in form of factorial completely randomized design with ...

Nitrogen metabolism of planktonic populations in coastal waters of the southern Scotia Sea was studied in February-March 1981 aboard R/V M e l d l e . In spite of the high concentration of nitrate present in these waters (21 to 29 FM), up to 93 % of phytoplankton nitrogen was assimilated in the form of ammonium, with the overall mean being 78 %. Time course experiments showed that uptake of nit...

Currently, nitritation-anammox (anaerobic ammonium oxidation) bioreactors are designed to treat wastewaters with high ammonium concentrations at mesophilic temperatures (25 to 40°C). The implementation of this technology at ambient temperatures for nitrogen removal from municipal wastewater following carbon removal may lead to more-sustainable technology with energy and cost savings. However, t...

Ammonium and nitrate uptake was measured in 6 European tidal estuaries (Ems. Rhine, Scheldt, Loire, Gironde and Douro) using I5N-tracer techniques. Uptake rates of ammonium and nitrate ranged from 0.005 to 1.56 pmol N 1-' h-I and 0.00025 to 0.25 pmol N 1-' h-I, respectively, and differed significantly between and within estuaries. Analysis of nitrogen uptake using the relative preferential inde...