Bioremediation of endosulfan under solid-state and submerged fermentation of Pleurotus ostreatus and its correlation with lignolytic enzyme activities

Abstract

During the past few decades, organochlorine pesticides (OCPs) have emerged as global pollutants. Despite their ban, Endosulfan, one of the most persistent and toxic pesticides of the OCP group, was most commonly used in agriculture and other sectors. Endosulfan bioremediation experiments were conducted using Pleurotus ostreatus. The Endosulfan spiked wheat straw was inoculated with Pleurotus ostreatus and incubated under solid state and submerged fermentation conditions. The enzyme production and activities and degradation of Endosulfan isomers (α-and β-isomers) was monitored periodically for 40 days. Degradation rate and half-life (DT50) of both the isomers was calculated using a simple first-order kinetics model. Under both conditions, the addition of Endosulfan showed stimulating effects on MnP and laccase enzyme activities. Activities of both the enzymes at each time interval were higher in solid-state fermentation than submerged fermentation. The degradation of α-isomers was higher under solid-state fermentation than submerged fermentation, while the inverse was true for β-isomer. The calculated DT50 of α-and β-Endosulfan under solid-state fermentation was 3.99 and 44 days, respectively, with 73.69±3.43 mg kg-1 Endosulfan sulfate accumulation. While under submerged fermentation conditions, DT50 of α-and β-Endosulfan was 10 and 20 days, respectively. The formation of Endosulfan sulfate, under submerged fermentation conditions, was maximum at day 10 (39.67±5.73 mgL-1) and declined to 8.71±3.24 mgL-1 until the end of incubation. A poor correlation between degradation and activities of both enzymes was observed. Rapid reduction in Endosulfan sulfate under submerged fermentation revealed its ascendancy in degradation over solid-state fermentation.