fuel in a soil with a long history of contamination contrary to a non-contaminated soil.
As a consequence, ammonia oxidation does not constitute a limited step in
nitrification process (Appl. Environ. Microbiol. 65 (1999) 4008). Moreover, this type
of soil also has had the opportunity to develop an abundant microbial population able
to metabolise the diesel hydrocarbons. Whether the properties of soil with a long
history of diesel fuel contamination may affect the activity of nitrite-oxidising
bacteria was investigated. It was observed that re-exposure of soil to diesel fuel
apparently stimulated the proliferation of nitrite-oxidising bacteria, as determined by
most probable number (MPN) culture technique and MPN-polymerase chain reaction
technique. The potential of nitrite-oxidising activity in soil treated with diesel fuel
was about 4 times higher than in the control without addition. In the presence of
diesel fuel and ammonium, the potential nitrite-oxidising activity was 40% higher than
in presence of ammonium only. However, in the presence of hydrocarbon only, low
proliferation of Nitrobacter was observed, probably because the heterotrophic
bacteria were strongly limited by lack of nitrogen and did not produce sufficient
organic metabolites that could be used by the Nitrobacter cells.
& 2004 Elsevier GmbH. All rights reserved.
ARTICLE IN PRESS
www.elsevier.de/micres
KEYWORDS
Diesel contamination
of soils;
Hydrocarbon
pollution;
Nitrification;
Nitrite-oxidising
bacteria;
Nitrobacter
0944-5013/$