Molecular approaches have revealed considerable diversity and uncultured novelty in natural prokaryotic populations, but not direct links between the new genotypes detected and ecosystem processes. Here we describe the influence of the structure of communities of ammonia-oxidizing bacteria on nitrogen cycling in microcosms containing natural and managed grasslands and amended with artificial sh...

Cell-specific ammonia oxidation rate (AOR) has been suggested to be an indicator of the performance of nitrification reactors and to be used as an operational parameter previously. However, published AOR values change by orders of magnitude and studies investigating full-scale nitrification reactors are limited. Therefore, this study aimed at quantifying ammonia-oxidizing bacteria (AOB) and est...

We studied controls on nitrification in an undisturbed water-limited ecosystem by inhibiting autotrophic nitrifying bacteria in soils with varying levels of vegetative cover. The activity of nitrifying bacteria was disrupted using nitrapyrin, 2-chloro-6-(trichloromethyl)-pyridine, under field conditions in three microenvironments (underneath shrubs, next to grasses and in bare soil). Ammonia-ox...

Nitrification was studied with microsensors and fluorescence in situ hybridization (FISH) in sandy sediment of a small lowland stream. Comparative measurements were performed in both intact field sediment (‘natural sediment’) and sediment from the same site after processing for a laboratory incubation experiment (‘manipulated sediment’). In natural sediment, the nitrification activity and abund...

In order to elucidate and quantify nitrogen transformations occurring during aerobic treatment of pig slurry, two laboratory experiments were carried out with contrasting levels of aeration, high level (experiment 1) and low level (experiment 2) of aeration. During these experiments, after reaching steadystate conditions, a single pulse of NO3 -N tracer was added directly to the reactor. When n...

ABSTRACT The common corrosion inhibitor, 1H-benzotriazole (Bz), found as a component of glycol-based aircraft deicers, and its derivatives such as 5-chloro-1H-benzotriazole (CBz), 1-hydroxy-benzotriazole (HBz), and 5-methyl-1H-benzotriazole (MBz), are all potential nitrification inhibitors. The inhibitory effect on the nitrification of urea-N fertilizer in agricultural soils was examined over a...

Field measurements in the Arcachon Bay (south-west France) indicated anaerobic production of NOx via nitrification which was coupled to the reduction of Mn-oxides. To provide evidence for the occurrence of this process, laboratory microcosm experiments were set up. A N tracer based approach was used to track if NOx produced through Mn-oxide mediated anaerobic nitrification would be reduced to N...

*Correspondence: Kazuo Isobe, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan e-mail: akisobe@ mail.ecc.u-tokyo.ac.jp Topography affects the soil physicochemistry, soil N dynamics, and plant distribution and growth in forests. In Japan, many forests are found in mountainous area...

Soil microorganisms are important sources of the nitrogen trace gases NO and N2O for the atmosphere. Present evidence suggests that autotrophic nitrifiers such as Nitrosomonas europaea are the primary producers of NO and N2O in aerobic soils, whereas denitrifiers such as Pseudomonas spp. or Alcaligenes spp. are responsible for most of the NO and N2O emissions from anaerobic soils. It has been s...

Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have doubled global annual reactive N inputs in the past 50-100 years, causing deleterious effects on the environment through increased N leaching and nitrous oxide (N2 O) and ammonia (NH3 ) emissions. Leaching and gaseous losses of N are greatly controlled by the net rate of microbial nitrification. Exten...