Sequencing of ammonium oxidising communities from soil used in an OECD nitrogen transformation study. Microbial community analysis in relation to soil risk assessment procedures

Man-made compounds are regularly introduced into the environment, either intentionally like plant protection products or unintentionally in the case of veterinary medicines and human pharmaceuticals. To safeguard terrestrial ecosystems, assessments of environmental safety are crucial. The impact of chemicals on microorganisms is assessed by considering potential long-term effects on the nutrient cycling capability, for example soil nitrogen cycling. Nitrification is an essential part of the nitrogen cycle transforming ammonium to nitrate in two stages. It is thought that nitrification is highly sensitive to disturbances given the highly specialised lifestyle of nitrifiers. We assessed how the procedures applied in the standard soil nitrification test using ethofumesate as model compound influence nitrogen transformation and nitrifying communities with regards to origin of soil (naiive or agricultural), addition of Lucerne and the experimental incubation for 28 days. Bacterial and archaeal ammonium oxidising organisms were studied using pyrosequencing of the amoA gene.