Bio-decolorization and detoxification of textile dye by bacterial consortium isolated from textile effluents

Autochthonous microbial community thriving in textile wastewater can be optimized to potentially decolorize and detoxify recalcitrant dyes used in textile dyeing plants. The present study investigates the bio-decolorization and detoxification of selected dyes using autochthonous bacterial consortium from textile effluents from Dhaka, Bangladesh. The consortia were obtained from dye-containing effluents released from different textile dyeing plants around Dhaka. Following enrichment and primary screening using dye-supplemented chemically defined media, individual bacteria were identified using conventional phenotypic and molecular methods. Dye decolorization assays were performed using both consortium and individual isolates. The effect of temperature, pH and dye concentration on decolorization were observed. Additional decolorization of dyes, including Synozol Golden Yellow HF-2GR (SGY) and Synozol Navy Blue K-BF (SNB) was also conducted. Phytotoxicity and microbial toxicity tests were performed to assess the toxic nature of the decolorized product. Five consortia composed of different bacterial species including Pseudomonas aeruginosa, Klebsiella spp. , Enterobacter spp. and Acinetobacter baumanii were selected based on their decolorization potential. The consortia were found to be better at bio-decolorization than the individual bacteria ( p < 0.05), as a 3 to 5-fold difference in decolorization percentage was observed. Up to 95% of SAR decolorization was observed within 96 h, and effective decolorization was also observed for SGY (89%) and SNB (83%). Consortium 7 showed the best decolorization potential (80%, 87%, and 86% decolorization of SAR, SGY, and SNB, respectively), and was composed of Klebsiella spp., Enterobacter spp. and P. aeruginosa. The consortia performed best at 30-37 °C and pH5, and optimized physicochemical parameters allowed up to 100% decolorization of SAR and SGY by Consortium 3 and 7 within 96 h. The biodegraded products of SAR were also found to be non-toxic for microbes and plants. The results suggest the excellent potential of autochthonous consortia for bioremediation of synthetic dyes, and needs to be further optimized to achieve an industrially applicable wastewater treatment method.