Enhanced Biosynthesis of Laccase and Concomitant Degradation of 2, 3-Dichlorodibenzo-p-Dioxin by Pleurotus florid

Abstract

Objective: Laccase enzyme has proven to be an excellent catalyst for the degradation of dioxin into less toxic metabolites. In the present study, submerged culture conditions of Pleurotus florida were optimized by Taguchi design of experiments (DOE) for enhanced laccase production and 2, 3-Dichlorodibenzo-p-dioxin (2, 3-DCDD) degradation. Methods/Statistical Analysis: An orthogonal array layout of L-8 (27) was constructed using Qualitek-4 software with seven influential factors at two levels with "bigger is better" quality character. Findings: At individual levels, copper showed maximum effect and at the interactive level RPM accounted for more than 90 % of the severity index (SI) with duration. The optimized conditions: nitrogen 0.2 mM; copper 0.04 mM; pH 5.5; temperature 25°C, inoculum size 10% w/v, RPM 120 and 30 days duration predicted an increase of laccase production by 24.4% (621.36 U to 773.04 U) and dioxin (initial concentration of 10 ppm) degradation by 20.2% (83.1% to 100%). The validation experiments confirmed an improvement of laccase production by 21.5% and exhibited complete degradation of 2, 3-DCDD. Application: This is the first report on parametric optimization of laccase production by P. florida by Taguchi DOE and its utilization for complete degradation of chlorinated dioxin molecules. The optimized process parameters can be adopted for the large-scale production of laccase for bioremediation of dioxin.