A sequential aerobic/microaerophilic decolorization of sulfonated mono azo dye Golden Yellow HER by microbial consortium GG-BL

This study is a part of efforts to develop new batch method with the help of prepared consortium GG-BL using two microbial cultures viz. Galactomyces geotrichum MTCC 1360 and Brevibacillus laterosporus NCIM 2298, varying oxidation conditions for the bio-treatment processes to produce reusable water by decolorization of Golden Yellow HER (GYHER) to less toxic metabolites. Consortium was found to be much faster for decolorization and degradation of GYHER as compared to the individual strains. The intensive metabolic activity of these strains led to 100% decolorization of GYHER (50 mg l⁻¹) within 24 h with significant reduction in chemical oxygen demand (84%) and total organic carbon (63%). The presence of veratryl alcohol oxidase, NADH-DCIP reductase and induction in laccase, tyrosinase, azo reductase and riboflavin reductase during decolorization suggests their role in decolorization process. Substrate staining of nondenaturing polyacrylamide electrophoresis gel (PAGE) also confirms induction of oxidative enzymes during GYHER degradation. The degradation of the GYHER into different metabolites by individual organism and in consortium was confirmed using High Performance Thin Layer Chromatography (HPTLC), High Performance Liquid Chromatography (HPLC), Fourier Transform Infra Red Spectroscopy (FTIR), Gas Chromatography Mass Spectroscopy (GC–MS) analysis. Phytotoxicity studies revealed nontoxic nature of the metabolites of GYHER.