Ammonium and nitrate are the prevalent nitrogen sources for growth and development of higher plants. 15N-uptake studies demonstrated that ammonium is preferred up to 20-fold over nitrate by Arabidopsis plants. To study the regulation and complex kinetics of ammonium uptake, we isolated two new ammonium transporter (AMT) genes and showed that they functionally complemented an ammonium uptake-def...

Nitrification and dissimilatory reduction of nitrate to ammonium were measured concomitantly with nitrogen release from marine coastal sediment samples from 2 fjord sill stations. Dissimilatory ammonium production (DAP) and nitrification were measured using core injections of "NO; and H1"CO;, respectively. DAP was detected in all segments of the cores by tracing "NH: evolved from the added "NO;...

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 ...

xanthan gum is an extracellular polysaccharide produced by various xanthomonas species such as x. campestris . the objective of present study was to investigate the influence of different carbon and nitrogen sources on xanthan gum production by x. campestris . using an experimental response surface methodology (rsm) complemented with a central composite design (ccd), the impact of peptone, lact...

parsley has a very high nutritional value, containing a, b and c vitamins and mineral nutrients. in order to investigation of the effect of different nitrogen sources on parsley an experiment conducted in a factorial combination of three nitrogen forms (calcium nitrate, ammonium sulphate and urea) and four nitrogen levels (0, 100, 125, 150 kg ha-1) by using a factorial experiment based on rando...

The free radical nitric oxide (NO) is an important signaling molecule in the gastrointestinal tract. Besides eukaryotic cells, gut microorganisms are also capable of producing NO. However, the exact mechanism of NO production by the gut microorganisms is unknown. Microbial NO production was examined under in vitro conditions simulating the gastrointestinal ecosystem using L-arginine or nitrate ...

Nanoscale zero valent iron (NZVI) based microbial denitrification has been demonstrated to be a promising technology for nitrate removal from groundwater. In this work, a mathematical model is developed to evaluate the performance of this new technology and to provide insights into the chemical and microbial interactions in the system in terms of nitrate reduction, ammonium accumulation and hyd...

The effects of nitrate and ammonium addition on net and gross photosynthesis, CO(2) efflux and the dissolved inorganic carbon compensation point of nitrogen-limited Selenastrum minutum Naeg. Collins (Chlorophyta) were studied. Cultures pulsed with nitrate or ammonium exhibited a marked decrease in both net and gross photosynthetic carbon fixation. During this period of suppression the specific ...

Samples from six private wells formerly used as sources for drinking water by the residents of Washington County (Weiser, Idaho) were collected to assess the impact of a nearby confined animal feeding operation (CAFO) on the quality of the local groundwater. All six samples were found contaminated by two veterinary antimicrobials, sulfamethazine (at concentrations from 0.076 to 0.22 microg/l) a...

introduction soil salinity is a major limiting factor in agricultural development within iran. nitrogen is the most important nutrient that its uptake is limited over other elements under saline conditions due to decrease in the permeability of plant roots, soil microbial activity and mineralization of organic compounds and nitrate uptake by high concentrations of chloride anions in the root zo...