Competition for nitrate between denitrifying Pseudomonas stutzeri and nitrate ammonifying enterobacteria

Abstract

Competition for nitrate between nitrate ammonifying enterobacteria and a denitrifying pseudomonad was studied in electron acceptor‐limited chenostats. In pure cultures, using different carbon and energy sources, the C/N‐ratio needed for denitrification is far lower than that required for nitrate ammonification. In mixed cultures of Citrobacter freundii and Pseudomonas stutzeri, competing for nitrate with l‐lactate as electron donor, the nitrate ammonifying organism dominated at dilution rates of D ≤ 0.14 h−1. Competition for both nitrate and l‐lactate at a dilution rate of D = 0.05 h−1 always resulted in the coexistence of both species. Using glucose as additional carbon source, the final ratio of nitrate ammonifying and denitrifying organism depended on the C/N‐ratio as well as on the dilution rate. The results of the study are discussed with respect to field data.

The Fate of 15 N-Nitrate in Healthy and Declining Phragmites australis Stands

“…The presence of the aerenchymatous plant is important for the uptake of nitrate and the release of oxygen into the root zone. Furthermore, the concentrations and the ratio of the available electron donor and acceptor were found to be less important than previously reported [12,20,25,26,27], at least in these freshwater saturated sediments in the presence of an aerenchymatous plant.…”

“…However, some studies showed that DNRA could be overestimated in waterlogged or estuarine sediments, due to incomplete blockage of nitrous oxide reductase by acetylene or nitrate uptake by microphytes [4,21]. The main factors regulating which of the two nitratereducing processes will be favored are the concentrations and ratios of available electron donors and acceptors [20,27]. Aerenchymatous plants create an oxic-anoxic interface in the root zone by releasing oxygen into this zone [2,22].…”

Seasonal variation in denitrification rates and nitrous oxide fluxes in intertidal sediments of the western Wadden Sea

“…Summer, August 1989; (4-) winter, January 1990 observations suggest that in summer the ambient NO: concentration is below, though in winter well above, the half-saturation value (K,) for denitrification, which is usually in the range of 2 to 15 PM (Murray et al 1989, Rehr & Klemme 1989. Once the NOT supply from the overlying water to the denitrification zone increases again (October), other mechanisms are responsible for the considerable variation in denitrification rates in winter and early spring.…”

A model discriminating denitrification and dissimilatory nitrate reduction to ammonium in a temperate estuarine sediment

“…Consequently, any model of nitrate reduction must account for the effect of the regulating factors. These include temperature (King & Nedwell 1984 Ogilvie et al 1997a), the labile carbon:nitrate ratio (Rehr & Klemme 1989), pH (Kim et al 1997) nitrate concentrations (King & Nedwell 1987) and the type of organic substrate used (Herbert 1982). The aim of this work is to develop a diagenetic model with a more complete description of nitrate reduction by including DNRA.…”