Enhanced Degradation of the Fungicide Vinclozolin: Isolation and Characterisation of a Responsible Organism

Enhanced degradation of the fungicide vinclozolin was stimulated by multiple successive applications to a soil without any history of previous pesticide input. A vinclozolin-degrading bacterium isolated from this soil was identified as a strain of Pseudomonas putida. This organism metabolised vinclozolin as a source of carbon, but it would neither grow with nor transform any other closely related dicarboximide fungicides nor the degradation product, 3,5-DCA. The degradation of vinclozolin by cultures of P. putida St-1 was investigated under various culture conditions; biodegradation was optimal at 23°C, pH 6·5 and inoculum densities of 107 cells ml−1 but cultures would grow from as little as 100 cells ml−1. Amendments of the vinclozolin-degrading isolate to soil previously untreated with the fungicide caused rapid degradation of applied vinclozolin, whereas amendments of boiled cells, or viable cells grown in the absence of vinclozolin, produced no discernible effect on the rate of vinclozolin degradation.