Bioremediation of endosulfan-contaminated soil by using bioaugmentation treatment of fungal inoculant Aspergillus niger

The persistence of endosulfan and intermediate metabolite endosulfan sulfate in the environment and their toxic effects on biota necessitate their removal. This study investigated the bioaugmentation of endosulfan-contaminated soil by fungal inoculant Aspergillus niger ARIFCC 1053. The influence of bioaugmentation by A. niger on endosulfan- contaminated soil was evaluated with the help of change in pH and released chloride, and by thin layer chromatography and gas chromatography analysis. Its effects on soil functionality were monitored by estimating dehydrogenase and arylsulfatase enzyme activities. The endosulfan degradation reached an undetectable level on day 15. The pH of the medium was nearly neutral (6.9) at the time of inoculation and it decreased to 3.6 on day 15. The amount of chloride released at particular intervals in the endosulfan degradation ranged from 28 μg mL^–1 to 104 μg mL^–1. Change in pH and the increase in released chloride correlated with metabolic activities involved in the simultaneous degradation of endosulfan. Endosulfan sulfate, an intermediate metabolite, was detected and had disappeared on day 11 of the process. The increase in enzyme activities is an indicator of soil fertility and suggests possible involvement of these enzymes in endosulfan degradation. These results demonstrate that bioaugmentation by A. niger may be a viable tool for the remediation of soil contaminated with endosulfan.