Enzymatic degradation of textile dye Reactive Orange 13 by newly isolated bacterial strain Alcaligenes faecalis PMS-1

Abstract

The aim of the present work is to evaluate degradation of textile dye Reactive Orange 13 (RO 13) by newly isolated bacterial strain. The bacterial isolate was identified as Alcaligenes faecalis PMS-1 based on 16S rDNA analysis. The isolate was able to decolorize cyanuric chloride based RO 13 under the static anoxic condition with an average decolorization rate of 24.75mgl−1h−1; which is approximately 38.13 times higher than the literature reported value. Kinetic study of decolorization experiments approximates the first-order reaction. The activation energy (Ea) and frequency factor (Ao) were calculated for decolorization reaction using Arrhenius equation. The maximum rate (Vmax) and Michaelis constant (Km) were found to be 27.1mgl−1h−1 and 105mgl−1, respectively by using Michaelis–Menten kinetics. Noteworthy induction of Veratryl Alcohol Oxidase, Tyrosinase and NADH–DCIP reductase enzymes were observed during decolorization of RO 13, which suggested the enzymatic decolorization and degradation of reactive dye. UV–Vis spectroscopy, FTIR and HPLC analysis confirmed decolorization of RO 13. Dye degradation pathway was determined through enzyme assay study and GC–MS analysis. The final products, naphthalene and 6-[(4-chloro-1,3,5-triazin-2-yl) amino]-2-iminonaphthalen-1(2H)-one were characterized by GC–MS analysis. The phytotoxicity study revealed the degradation of RO 13 into non-toxic product by PMS-1.