Biotransformation of mixture of dyes by enriched bacterial consortium ASD

Dye effluents released from textile industries has gradually entrenched the roots of peril to majority of the water bodies. Considering the alarming need of innovative bioremediation technologies, the present study aims to evaluate the biodegradation potential of a bacterial consortium ASD for mineralization of a mixture of structurally different dyes. Consortium ASD, developed from dye contaminated soil from Vatva industrial estate, constitutes of four bacterial strains viz. Pseudomonas sp., Brevibacillus sp. and two strains of Stenotrophomonas sp. The intense metabolic activity of these strains together, led to 94% ADMI removal (American dye Manufacturers Institute) of 100 mg l⁻¹ of a mixture of dyes in the presence of starch (0.1%, w/v) and proteose peptone (0.4%, w/v) within 24 h at 37°C under static (microaerophilic) condition and could tolerate up to 400 mg l⁻¹ of dye mixture. Consortium was also able to reduce total organic carbon and chemical oxygen demand by 85 and 78% within 24 h. Significant level of various oxido-reductive enzymes observed during decolourization by the consortium, confirms their involvement in the degradation process. Biotransformation of the mixture of dyes to less toxic byproducts was confirmed using Fourier transformed infrared spectroscopy, NMR, GC–MS analysis, and phytotoxicity test. Results showed a suitable application of consortium ASD for the biological processing of dye containing wastewaters.