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(W/MF173) Influence of macroelement limitation on the competitive success of organophosphate degrading bacteria. Sprenger, Wander1,2, Dijkstra, Annereinou2, Parsons, John1, van Noort, Paul2, 1 2 ABSTRACT- The efflux of pesticides into surface waters in areas of intensive agriculture poses a threat to aquatic organisms as well as, possibly, the production of drinking water. The rate of elimination of these pollutants may differ up to three orders of magnitude for the same chemical compound between different locations. Therefore, it is crucial to elucidate what factors determine the competitive success of aerobic organoheterotrophic microorganisms that are capable of bioconversion of pesticides into less toxic products. In this study, 400 ml continuous cultures were inoculated with ditch water, and heterotrophic aerobic microorganisms were cultivated for extended periods of time under carbon, nitrate or phosphate limitation. In some of the experiments, Flavobacterium sp. ATCC27551, known to be capable of growth on the insecticide diazinon, was introduced into the cultures. The presence of Flavobacterium was monitored by measuring the enhanced pesticide-degrading activities and by selective plating methods. In addition, the shifts in species composition and changes in organophosphate pesticide degrading capability in the mixed cultures were studied by Denaturing Gradient Gel Electophoretic (DGGE) analysis of PCR-amplified rRNA gene fragments and HPLC analysis of pesticide degradation. Key words: pesticides, biodegradation, nutrients, species composition |
