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4D - Veterinary Medecine (MO13/15) Antibiotics cause pollution-induced community tolerance in soil bacteria. Schmitt, Heike1, Martinali, Bennie1, van Beelen, Patrick2, Tolls, Johannes3, van Leeuwen, Kees4, 1 Institute for Risk Assessment Sciences, University of Utrecht, Utrecht, the Netherlands, the Netherlands2 National Institute for Public Health and the Environment, Bilthoven, the Netherlands, the Netherlands3 Henkel KGaA, Duesseldorf, Germany, Germany4 Institute for Health and Consumer Protection, Ispra, Italy, Italy ABSTRACT- Veterinary antibiotics can enter the environment through manuring of agricultural soils with slurry of treated animals. The environmental hazards associated with this exposure are largely unknown, but preliminary studies have shown that effects on soil microorganisms may occur. To further investigate the effect of antibiotics on soil bacteria, the approach of 'pollution-induced community tolerance' or PICT was used. PICT is based on the changes in community composition brought about by exposure to a pollutant, resulting in a decreased sensitivity towards this particular pollutant. PICT was studied in soils spiked with the antibiotics, sulfachloropyridazine, oxytetracycline and tylosin. As the addition of organic fertilizer increases the toxic effect of antibiotics, the spiking procedure had been optimised with regard to amount and nature of organic fertilizer, as well as PICT selection and detection time. The sensitivity distribution of the microbial communities was analysed before and after exposure of the soils using a functional test based on metabolization of 31 simple substrates (Biolog ecoplate). An increasing tolerance of the bacterial communities towards these antibiotics was detected and statistically analysed. The three compounds were compared with regard to their effects and their environmental chemistry. Key words: pollution-induced community tolerance, antibiotic, veterinary drugs, soil bacteria |
