Screening of soil fungi for in vitro degradation of endosulfan

Intensive use of endosulfan has resulted in contamination of soil and water environments at various sites in Pakistan. This study was conducted to isolate efficient endosulfan-degrading fungal strains from contaminated soils. Sixteen fungal strains were isolated from fifteen specific sites by employing enrichment techniques while using endosulfan as a sole sulfur source, and tested for their potential to degrade endosulfan. Among these fungal strains, Chaetosartorya stromatoides, Aspergillus terricola, and Aspergillus terreus degraded both alpha- and beta-endosulfan upto 75% in addition to similar to 20% abiotic degradation of the spiked amount (100 mg l(-1)) in the broth within 12 days of incubation. Biodegradation of endosulfan by soil fungi was accompanied by a substantial decrease in pH of the broth from 7.0 to 3.2. The major metabolic product was endosulfan diol along with very low concentrations of endosulfan ether. Maximum biodegradation of endosulfan by these selected fungal strains was found at an initial broth pH of 6, incubation temperature of 30 degrees C and under agitation conditions. This study indicates that the isolated strains carried efficient enzyme systems required for bioremediation of endosulfan-contaminated soil and water environments.