Biodegradation and Detoxification of Malachite Green Dye Using Novel Enzymes from Bacillus cereus Strain KM201428: Kinetic and Metabolite Analysis

Abstract

Enzyme based degradation of organic pollutants is a promising detoxifying approach due to the promiscuous nature of the enzyme, efficiency, cost effective and ecofriendly. In the present study, we have carried out detailed decoloration and degradation studies on a model triphenyl methane group of dyes (Malachite Green dye (MG)) using a newly isolated enzyme from Bacillus cereus KM201428 under the static condition. Biodegradation of dyes was monitored by UV-VIS spectrophotometer and the resultant metabolites analyzed by Liquid Chromatography–Hybrid Quadrupole Time of Flight Mass Spectrometry (LC–QToF-MS) and Gas Chromatography/Mass Spectrometry (GC - MS). Metabolite analysis results revealed that enzymatic degradation of MG dye resulted in complete mineralization and benzene ring-removal; the latter known for organic dye toxicity. Kinetic study results revealed that first-order kinetic model was best applicable for describing MG dye decoloration. Michaelise-Menten kinetics, Lineweaver–Burk plot and Eadie-Hofstee plot models were used to establish the kinetic parameters for the dye decoloration. Lineweaver–Burk plot provided the best theoretical correlation of the experimental data with maximum rate (Vmax) of 17.70 mg l-1h-1 and Michaelis constant (Km) of 124 mgl-1. Results provide evidence that crude enzyme from Bacillus cereus strain KM201428 offers an effective, renewable, ecofriendly and affordable biotechnology for treatment of industrial effluents polluted with organic dye.