Persistence of bacterial denitrification capacity under aerobic conditions: The rule rather than the exception

Abstract

Bacterial decomposition of nitrate to dinitrogen and oxides of nitrogen, essential steps in the nitrogen cycle, are regarded as predominantly anaerobic processes. However, here we have shown, using simultaneous mass spectrometric monitoring of dissolved N2, NOx and O2, that in the laboratory a number of different bacteria can denitrify, even when O2 concentrations approach or exceed air saturation values. The proportions of gaseous end products vary from one organism to another and depend on the level of dissolved O2. We, therefore, suggest that aerobic bacterial denitrification, with the production of N2 and/or NOx, may, contrary to the beliefs of many, be as widespread and ecologically important as its anaerobic counterpart.

The anaerobic biodegradation of diethanolamine by a nitrate reducing bacterium

“…The observation that growth of DEA4 is more rapid under anaerobic conditions than aerobic is unexpected, but might be due to inhibition by oxygen or oxygen metabolites in the aerobic cultures. The limited nitrate reduction observed under aerobic conditions is not however surprising in view of recent observations (Lloyd et al 1987;Patureau et al 1994;Robertson & Kuenen 1984) that dissimilatory nitrate reduction by bacteria does always not require totally anoxic conditions.…”

N2O cycling at the core of the oxygen minimum zone off northern Chile

“…Our experiments corroborate the fact that denitrifiers are able to produce more N 2 O with high O 2 concentrations. Numerous laboratory experiments with denitrifying bacteria resulted in N 2 Opd being enhanced between ≈22 and 111 µM O 2 (Lloyd et al 1987, Otte et al 1996, Takaya et al 2003. Accordingly, denitrification can operate at even higher O 2 levels than assumed for natural conditions, presently not higher than ≈9.0 µM O 2 (Rönner & Sörensson 1985).…”

Coupling of microbial fermentation and respiration processes in an intertidal mudflat of the Elbe estuary

“…Aerobic N03-and Mn reduction may be advantageous to microorganisms that must adapt to fluctuating oxicsuboxic conditions in some sediments Nielsen et al 1990;Lloyd et al 1987). In the sediment surface of intertidal-flat sediments the changes in redox conditions might occur even within a single tidal cycle (Kerner et al 1990).…”