Evaluation of textile dye degrading potential of ligninolytic bacterial consortia

Abstract Elimination of synthetic azo dyes of textile industrial effluents still being a great challenge worldwide as it engenders several hazardous effects in the ecosystem. Bioremediation technology has remarkable potential to approach this kind of problem due to its environmentally friendly and economical nature. Ligninolytic enzyme systems seem to have shown great potential to degrade a variety of recalcitrant pollutants and xenobiotic compounds including dyes. This study aimed to isolate and identify ligninolytic bacterial consortium from Western Ghats foothill soil with the potential to degrade azo dyes. Nine ligninolytic bacterial strains were isolated from soil samples. All the strains were able to decolorize a mixture of azo dyes (DR 23, DB 15 and DY 12). Three potential strains with maximum dye decolorizing efficiency were selected and identified by 16S rRNA gene sequencing studies. The influence of bacterial monocultures and mixed cultures in the dye decolorization was studied with the selected strains. Three monocultures and four mixed cultures were developed and studied for their ability to decolorize MSM containing 200mg/l of azo dye mixture. The ligninolytic bacterial consortium WGC-D was found to be more effective which decolorized up to 75% of dye. The mechanism of dye decolorization was assessed by spectral studies. The changes in the UV spectrum of bacterial consortium treated and untreated samples validated that the mechanism of the decolorization process was biodegradation. The consortium removes 89% of COD and 84% of color from textile industrial effluent. The results reveal that the ligninolytic bacterial consortium could be useful as a candidate in the secondary screening process in the textile dye effluent treatment in industries.