Reductive Degradation of the Herbicide Isouron and Its Related Compounds by Pseudomonas putida

A strain of bacteria able to degrade isouron [3-(5-tert-butyl-3-isoxazolyl)-1,1-dimethylurea] reductively was isolated from the perfusate in soil perfusion culture. When the bacteria were cultured in a 5% yeast extract medium containing isouron at 28C without shaking, isouron was metabolized to 1-(1-amino-4,4-dimethyl-3-oxo-l-pentenyl)-3,3-dimethylurea during 6-day incubation. The strain of the bacteria was identified as Pseudomonas putida. The curing test and extraction of plasmid DNA from the cells seemed to show that the bacteria have no plasmid. The bacteria also reduced an isouron's related compound, 3-(5-tent-butyl-3isoxazolyl)-1-methylurea to 1-(1-amino-4,4-dimethyl-3-oxo-l-pentenyl)-3-methylurea. 3-(5tert-Butyl-isoxazolyl)urea and 5-tert-butyl-3-aminoisoxazole were slightly metabolized by the bacteria, but no degradation products were detected by thin-layer chromatography and densitometry.