Members of the Neisseria genus typically display the ability to carry out denitrification of nitrite to nitrous oxide as an alternative to oxygen respiration when oxygen is depleted. The key enzymes nitrite and nitric oxide reductase are found across the Neisseria genus. Within Neisseria meningitidis, however, a number of research groups have found that a significant proportion of strains lack ...

Abstract. Estuaries and rivers are important biogeochemical reactors that act to modify the loads composition of nutrients in coastal zone. In a case study during July 2013, we sampled an 80 km transect along Elbe Estuary under low-oxygen conditions. To better elucidate specific mechanisms estuarine nitrogen processing, tracked evolution stable isotopic nitrate, nitrite, particulate matter, amm...

All denitrifiers can keep the steady-state concentrations of nitrite and nitric oxide (NO) below cytotoxic levels by controlling the expression of denitrification gene clusters by redox signalling through transcriptional regulators belonging to the CRP (cAMP receptor protein)/FNR (fumarate and nitrate reductase regulator) superfamily.

In this work, a fuzzy-logic controller for minimization of the nitrous oxide emission from wastewater treatment plants is developed and tested in a simulation environment. The controller is designed in order to maintain a balance between production and consumption of nitrite by AOB and NOB microorganisms respectively. Thus, accumulation of nitrite is prevented and AOB denitrification, the main ...

Nitrous oxide (N 2 O) is an ozone-depleting substance and a harmful greenhouse gas with a global warming potential three hundred times larger than that of carbon dioxide. Measurement campaigns at domestic wastewater treatment plants (WWTPs) have found significant N 2 O emissions [1–5]. Specifically, N 2 O is found to be produced during the typical WWT processes involved in the nitrogen removal ...

A comparison was made of denitrification by Pseudomonas stutzeri, Pseudomonas aeruginosa, and Paracoccus denitrificans. Although all three organisms reduced nitrate to dinitrogen gas, they did so at different rates and accumulated different kinds and amounts of intermediates. Their rates of anaerobic growth on nitrate varied about 1.5-fold; concomitant gas production varied more than 8-fold. Ce...

Investigations were performed on soils of different acidity, ranging in the pH interval 4.65–5.80 (in water). Changes of the mineral nitrogen forms in the examined soils were studied by applying short-term incubation experiments performed under aerobic conditions, with a humidity of 30 % and a temperature of 20 °C, both with and without the addition of 100 and 300 ppm NH4–N. The results of the ...

Nitric oxide production was measured during nitrification in a laboratory-scale bioreactor, operated at conditions relevant to municipal nitrifying wastewater treatment plants. This study aims to determine which type of microorganism and which metabolic pathway is responsible for nitric oxide emission during nitrification. Simulation studies were used to identify which pathway is the main sourc...

We examined the influence of soil aeration state and plant root presence on the comparative survival of wild-type bacteria and isogenic Tn5 (Nir(sup-)) mutants lacking the ability to synthesize nitrite reductase. Two denitrifying Pseudomonas strains with different nitrite reductase types were used. Enumeration of bacteria in sterile and nonsterile soils was based on differential antibiotic resi...

The main aim of this study was to evaluate the performance of a modified sequencing batch reactor (MSBR) using fixed Kaldnes carriers fed with acclimated sludge for ammonium removal via simultaneous nitrification-denitrification (SND) in synthetic wastewater. The results exhibited a SND of 82.3% within a 450-minute cycle time which was higher than that of a SBR without carrier (69.83%). Nitrite...