Investigations with the isotopic tracer N16 have furnished definite evidence that ammonia is the key intermediate in nitrogen fixation by Azotobacter vinelundii (1). Direct isolation of the intermediate, however, has not been possible, apparently because ammonia is used so rapidly by this bacterium that it does not accumulate. In a study of the comparative biochemistry of nitrogen fixation, we ...

UNLABELLED A fundamental question in microbial physiology concerns why organisms prefer certain nutrients to others. For example, among different nitrogen sources, ammonium is the preferred nitrogen source, supporting fast growth, whereas alternative nitrogen sources, such as certain amino acids, are considered to be poor nitrogen sources, supporting much slower exponential growth. However, the...

deal effectively with the increased density of the pork industry in some areas and the increased public concerns regarding nutrient excretion and odour emissions. Successful management of nitrogen and phosphorus is key for sustainable pork production to address these public concerns. For example, nitrogen excretion in the form of ammonia is a concern because of its impact on the work environmen...

This study investigated the nitrifying community structure in a single-stage submerged attached-growth bioreactor (SAGB) that successfully achieved stable nitrogen removal over nitrite of a high-strength ammonia wastewater. The reactor was operated with intermittent aeration and external carbon addition (methanol). With influent ammonia and total Kjeldahl nitrogen ranging from 537 to 968 mg/L a...

The biological treatment of ammonia-rich landfill leachates due to an inadequate C to N ratio requires expensive supplementation of carbon from an external carbon source. In an effort to reduce treatment costs, the objective of the study was to determine the feasibility of nitrogen removal via the nitrite pathway during landfill leachate co-treatment with municipal wastewater. Initially, the la...

background: constructed wetlands (cw s ) are mimic filtration process in natural wetlands that effectively remove variety pollutants from wastewater. the main objective was the feasibility evaluation for using of subsurface flow constructed wetland in nitrogen and phosphorus removal from synthetic based on domestic wastewater in lab scale. methods: in this study, a synthetic wetland subsurface ...

M. Zapletal and P. Chroust Centre for Environment and Land Assessment Ekotoxa Opava, Horní nám. 2, 746 01 Opava, Czech Republic Abstract Modeling of the spatial distribution of ammonia (NH3) emissions on the territory of the Czech Republic within a 5x5 km grid is essential condition for the modelling of atmospheric transport and deposition flux of reduced nitrogen compounds and exceedances of c...

Ammonia oxidation plays a significant role in the nitrogen cycle in marine sediments. Ammonia-oxidizing archaea (AOA) and bacteria (AOB) are the key contributors to ammonia oxidation, and their relative contribution to this process is one of the most important issues related to the nitrogen cycle in the ocean. In this study, the differential contributions of AOA and AOB to ammonia oxidation in ...

Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; ...