BIODEGRADATION OF ORGANOPHOSPHOROUS PESTICIDES BY TWO FUNGI ISOLATED FROM PESTICIDE CONTAMINATED SOILS

Two fungal species which degrade the organophosphorus pesticides (OPs) folimat, phoxim, methamidsohphos and glyphosate were isolated and their biodegradation pathways were explored. Cell morphology analysis and ITS rRNA gene sequencing showed that the strains as Aspergillus oryzae (Ahlburg) E. Cohn) (ZHJ8) and Cladosporium cladosporioides (Fresen.) G.A. de Vries (ZHJ10). Both strains needed an external carbon source to degrade OPs, and ZHJ8 could use ethanol. Both strains could utilise nitrogen and phosphorus from OPs, both preferred to grow in acidic conditions, and both could degrade OPs efficiently at room temperature. The isolated strains could tolerate and degrade 2000 mg/l of methamidophos. Optimal conditions for methamidophos degradation by ZHJ8 were pH 5.0 - 5.5, 30 degrees C, and 1.5% glucose, while pH 4.0 - 4.5, 25 degrees C, and 1% glucose were optimal for ZHJ10. Based on the structure of the pesticides and the results of GC-MS, a possible biodegradation pathway was proposed.