Isolation and Characterization of a Triazophos-degrading Strain GS-1 and Its Degrading Characteristics

Abstract:

A strain designated as GS-1, capable of degrading triazophos efficiently, was isolated from the sludge in an organophosphate-pesticides wastewater treatment plant. Strain GS-1 was identified preliminarily as Diaphorobacter sp. based on its physiological and biochemical characters and the result of the 16S rDNA homologue sequence analysis. Strain GS-1 could grow with triazophos as its sole carbon source, and degrade 100 mg/L triazophos to non-detectable level within 12 h. The metabolite, 1-phenyl-3-hydroxy-1, 2,4-triazole, produced during triazophos biodegradation was finally transformed within 36 h. The optimal initial pH value and temperature for triazophos degradation by GS-1 was 7.0 and 30°C, respectively. Strain GS-1 could also degrade some other organophosphorus-pesticides such as fenitrothion, phoxim, chlorpyrifos and methyl-parathion. Strain GS-1 also showed chemoatxis to triazophos, fenitrothion and phoxim, indicating the close relationship between degrading and chemotaxis characteristics. This study demonstrated that strain GS-1 had great potential in the bioremediation of organophosphorus-pesticides contaminated sites.

Key words:Triazophos, Degradation, Diaphorobacter sp., Chemotaxis, 1-phenyl-3-hydroxy-1,2,4-triazole