Abstract
Biodegradation of chlorinated pesticide γ-hexachlorocyclohexane (lindane) by a nonwhite rot fungus Conidiobolus 03-1-56 is reported for the first time. Conidiobolus 03-1-56, a phycomyceteous fungus isolated from litter, completely degraded lindane on the 5th day of incubation in the culture medium, and GC-ECD studies confirmed that lindane removal did not occur via adsorption on the fungal biomass. Degradation studies using different medium compositions showed that nitrogen/carbon limiting conditions (stress conditions) and presence of veratryl alcohol, induced the secretion of extracellular oxidative enzymes, which enhanced the rate of lindance biodegradation. Under optimum nutrient-limiting conditions, GC-ECD and GC-MS analysis showed complete absence of any degradation metabolite, indicating that lindane was completely mineralized. Assays for tannic acid utilization and lignin peroxidase showed similar enzymatic profiles between Conidiobolus 03-1-56 and standard white rot fungi Pleurotus ostreatus 1200 and Trametes versicolor 1086. Although Conidiobolus 03-1-56 showed a reduced enzyme activity compared to white rot fungi, preliminary evidence indicates that enzymes responsible for lignin degradation by white rots play a key role in lindane degradation by Conidiobolus 03-1-56.