Abstract

This research article deals with biodegradation of azo dyes by a newly isolated bacterial strain from soil. Azo dyes are recalcitrant to the conventional modes of treatment due to their complex structure. This article reports decolorization of azo dye by, Gram positive, endospore forming and azo reducing, Bacillus megateriumITBHU01. Response surface methodology was used to optimize the important physical parameters screened by Placket–Burman design. Five physical parameters such as pH, temperature (°C), dye concentration (mg/L), inoculum size% (v/v) and time (h) were tested by using Placket–Burman design criterion and all five parameters showed significant effect (P < 0.05) on decolorization of orange G using B. megaterium ITBHU01. The values of parameters was optimized by applying central composite design (CCD) and the most suitable values for orange G decolorization byB. megaterium ITBHU01, as predicted by the statistical tool, was pH 6.9; temperature 37.0 °C; dye concentration 517 mg/L, inoculum size , v/v, (%) 5.5 % and time 23.7 h. At these optimum levels of parameters, bacterial decolorization of orange G by 94.48% was obtained under static conditions. Biodegradation and decolorization of azo dye, orange G, was confirmed using UV-VIS spectrophotometry, thin layer chromatography (TLC) and fourier transform infrared spectroscopy (FT-IR) and electron spray ionization mass spectrometry (ESI-MS) analysis.

Key words: Azo dye, Bacillus megaterium ITBHU01, biodegradation, orange G, response surface methodology.