Decolorization of Metanil Yellow G by a halophilic alkalithermophilic bacterial consortium

Increased temperature, salinity and alkalinity restrict the biodecolorization rate of textile wastewater. In the present study, the halophilic alkalithermophilic bacterial consortium ZSY, which can decolorize azo dyes under 10% salinity, pH 10 and 50 °C, was enriched. It can decolorize Metanil Yellow G (MYG) under a wide range of pH values (8-10), temperatures (40-50 °C), dye concentrations (100-400 mg/L) and salinity levels (1%-10%). Laccase (Lac), lignin peroxidase (Lip), nicotinamide adenine dinucleotide-dichlorophenol indophenol reductase (NADH-DCIP) and azoreductase are involved in the decolorization process. A decolorization pathway of MYG was proposed via gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR). The toxicity of MYG decreased after decolorization by ZSY consortium. A metagenomic sequencing approach was subsequently applied to identify the functional genes involved in decolorization. Overall, this halophilic alkalithermophilic bacterial consortium could be a promising candidate for the treatment of textile wastewater in environments with increased temperature, salinity and alkalinity.