Evaluation of Bacterial Consortium and Optimization of Growth Parameters for Effective Decolorization of Azo Dye Reactive Red 120

Document Type : Original Article


Department of Microbiology, Wilson College, Mumbai 400007, Maharashtra, India


Introduction: The effluents produced as a result of the dyeing process, especially by textile industries are a major threat to sustainable environmental development. Several challenges are observed in the treatment and disposal of complex azo dyes like Reactive Red 120 (RR120). The aim of the present study was to optimize the dye decolorization/degradation process by bacterial consortium.
Materials and Methods: The consortium consisted of three potential azo dye degraders i.e., Shewanella haliotis RDB_1, Shewanella putrefaciens RDB_2, and Aeromonas hydrophila RDB_3. It was prepared in 1:1:1 ratio and was named as RAR. This consortium was optimized under several nutritional and physicochemical parameters for effective decolorization of RR120.
Results: Complete decolorization of 50 ppm RR120 was achieved with 10% inoculum of 1.0 OD540 nm in 3% Yeast Extract (YE) medium under static conditions in 4 h. The optimum decolorization was observed between pH 7-8 and temperature 30°C-35°C. However, the consortium RAR showed significant activity between a pH range of 6-10, temperature 25°C-45°C and NaCl concentration up to 10%. The electron acceptors like nitrate and nitrite salts, and electron donors like urea and casamino acids negatively affected the decolorization rate of RR120. The sugars and organic acids failed to support decolorization in M9 medium. However, a varying effect was observed in the 3% YE medium. Soymeal peptone (prepared in distilled water) supported considerable decolorization but was not as effective as 3% YE medium.
Conclusions: Considering the above features and tolerance of consortium RAR to varied range of pH, temperature and NaCl concentration, it may be a suitable candidate for biodecolorization of textile effluents.