6533b863fe1ef96bd12c781d

RESEARCH PRODUCT

Effets simultanés de niveaux croissants de glucose et de pressions partielles en oxygène sur la dénitrification et la réduction dissimilative du nitrate en ammonium dans des échantillons reconstitués de sol

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International audience; Dissimilatory nitrate reduction to ammonium (DNRA) and its importance in comparison to denitrification were studied in soil samples artificially repacked to control water potential and porosity, and incubated for 72 h. Labelled nitrate (100 mg N.kg-’ dry soil, 21.8 % 15N in excess) and increasing levels of glucose-C (250, 500 and 1 000 mg glucose-Ckg-’ dry soil) were initially added to the soil samples to obtain increasing glucose-C/nitrate-N ratios of 2.5,5 and 10, which were then subjected to different 0, partial pressures (0,0.5, 1.0 and 2.0 % (v/v)). The results confirmed the good reproducibility of the experimental condi- tions using this method. Denitrification, rather than DNRA, was the dominant process in all the treatments developed during this experiment: N,O production in the presence of acetylene varied from 4.9 (glucose-C/nitrate-N = 2.5; 2 % OJ to 103.6 % (glucose- C/nitrate-N = 2.5; 0 % 0,) of the original nitrate whereas DNRA varied from 1.8 (glucose-C/nitrate-N = 2.5; 2.0 % O?) to 24.6 8 (glucose-C/nitrate-N = 10; 1 .O % OJ of the original nitrate. This work demonstrated that under these conditions, DNRA activity was less sensitive than denitrification to an inhibitory effect by 0, and reinforced the idea that carbon is the main driving factor regu- lating nitrate distribution between denitrification and DNRA.