High nitrate concentrations in salads and vegetables have attracted increased attention. It is well know that nitrate can cause serious health problems to humans such as methemoglobinemia of infants 111. Under certain conditions, specially in the human body carcinogenic nitrosamines can be formed [2]. However, nitrate content of different types of vegetables fluctuates substantially with variet...

The mineral nutrient needed in greatest abundance by plants is nitrogen. Plants, however, must compete for nitrogen in the soil with abiotic and biotic processes such as erosion, leaching, and microbial consumption. Soil nitrogen is also lost when crops are harvested and plant material is removed from the soil. To be competitive, plants have evolved several mechanisms to acquire nitrogen at low...

Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered preci...

The aim of this study was to investigate nitrification activity of urea and the assimilation of nitrate in a well aerated soil using perfusion technique with addition of glucose as an energy and carbon source. In this study, urea was rapidly nitrified by the bacteria in the saturated soil but its course of transformation to NO3 was not linear. There was an initial increase in the concentration ...

abstract by increasing the world population and more need to supply food, farmers attend to use of chemical fertilizers, organic manures and pesticides. also, applications of these agents without attention to their side effects, cause more problems to human health and environment. nitrate is one of the most important elements of organic manures, which leach through soil to surface and ground wa...

Acidovorax sp. strain NO1, isolated from gold mine soil, was shown to be a facultative anaerobic arsenite-oxidizing and nitrate-reducing bacterium. The reported draft genome predicts the presence of genes involved in arsenic metabolism, nitrate reduction, phosphate transport, and multiple metal resistances and indicates putative horizontal gene transfer events.

Soil amendment with pyrogenic carbon (biochar) is discussed as strategy to improve soil fertility to enable economic plus environmental benefits. In temperate soils, however, the use of pure biochar mostly has moderately-negative to -positive yield effects. Here we demonstrate that co-composting considerably promoted biochars' positive effects, largely by nitrate (nutrient) capture and delivery...

Kinetics of nitrite uptake and reduction by Chlamydomonas reinhardtii cells growing phototrophically has been studied by means of progress curves and the Michaelis-Menten integrated equation. Both uptake and reduction processes exhibited hyperbolic saturation kinetics, the nitrite uptake system lacking a diffusion component. Nitrite uptake and reduction showed significant differences in K(s) fo...

Streptomyces coelicolor is an obligate aerobic, filamentous soil-dwelling bacterium. Remarkably, the genome of S. coelicolor has three copies of the narGHJI operon that encodes respiratory nitrate reductase. This review summarizes our current views on the requirements for multiple nitrate reductases in S. coelicolor.

The influence of biological soil crusts (BSCs) on the small-scale spatial distribution of inorganic nitrogen (N) in drylands is largely unknown, despite their known impact and importance on the N cycle in these environments. We evaluated how perennial plants and BSCs affected small-scale spatial patterns of soil inorganic N (ammonium and nitrate) availability in a semiarid grassland from Spain....