Screening,Identification and Characterization of a Dimethoate Degrading Fungus

By using liquid enrichment culture,a fungus strain L3 was isolated and selected from sample which had been polluted by dimethoate for a long time.The strain was idendified as Aspergillus nomius on the basis of morphological observing and phylogenetic inference based on ITS sequence and analysis.The strain was able to utilize dimethoate when carbon source coexisted.Strain L3 could endure high concentration of dimethoate.In flask test strain L3 degraded 29.2% of dimethoate(2 000 mg·L-1) within 120 h,and the maximum tolerance concentration of dimethoate reached 6 000 mg·L-1.For strain L3,the optimum pH and temperature for the growth and the degradation of dimethoate was 28 ℃,7.0 respectively.The degradation curve of dimethoate under the action of L3 showed that after a 24 h's lag phase,the degradation entered exponential phase,and the degradation rate reached 29.2%.The growth of strain L3 was restrained in the first 24 h,and in the followed 72 h the growth of strain entered flourish phase,but in the last 24 h entered wane.The two curves,the growth of strain L3 and the degradation of dimethoate by strain L3,were accordant,and in the beginning strain L3 utilized carbon source preferentially.Strain L3 was also able to degrade other organophosphates well such as phoxim and acephate.When the concentration reached 5 000 mg·L-1,strain L3 could degrade 95.3% phoxim and 65.9% acephate,indicating that the degradability of strain L3 was broad-spectrum.