Bioaugmentation of endosulfan contaminated soil in artificial bed treatment using selected fungal species

Pollutants when incorporated in the soil lead to adverse effect on soil quality. Bioaugmentation provides very attractive, eco-friendly, and economic solution to problems associated with hazardous pollutants. The present study conducted biodegradation potential of four fungal species namely; Cladosporium cladosporioides, Penicillium frequentans, Trametes hirsuta, and Trametes versicolor to degrade endosulfan in soil using artificial bed. Individual fungi as well as their consortium are able to degrade endosulfan in soil. Toxicological effect of endosulfan and its degradation products in soil fertility was also evaluated during study. To evaluate the toxicological effect of endosulfan and its degradation products in soil fertility, soil pH, total microbial population and the soil enzymes activity were also analyzed. At the end of 30 days of incubation period, maximum per cent degradation of endosulfan was observed in soil augmented with T. hirsuta (86.23%), followed by T. versicolor (67.35%) which was at par with fungal consortium (63.49%). Degradation of endosulfan in soil treated with C. cladosporioides and P. frequentans was 60.37% and 56.18%, respectively. In addition, degradation of endosulfan decreased in all treatments as its concentration increased in soil. All tested fungi degraded α-endosulfan more efficiently than β-endosulfan. At the end of experiment (after 30 days), maximum degradation of both isomers was recorded in soil augmented with T. hirsuta (α = 93.03 ± 2.86 and β = 79.42 ± 2.71%). Fungi which showed more endosulfan degradation also produced more endosulfan sulfate in soil. However, less endosulfan sulfate was recorded in T. hirsuta and T. versicolor, though they degraded endosulfan more efficiently. pH in natural soil (control) and abiotic control remain at par during the complete incubation period and ranged between 7.45 ± 0.03 to7.49 ± 0.01. In soil treated with T. hirsuta and T. versicolor, pH was decreased significantly to acidic range (6.44 ± 0.04 and 6.64 ± 0.01, respectively). In soil treated with fungal consortium, pH increased initially (7.57 ± 0.04), but later it was found to decrease (7.16 ± 0.03). Usually, after an initial toxic effect, mineralization of endosulfan leads to an increase in microbial populations and enzyme activities in bioaugmented soil, and the efficient fungi caused more pronounced increment.