A Comparative Study of Biodegradation of Textile Azo Dyes by Escherichia coli and Pseudomonas putida

Azo dyes are synthetic in origin having complex aromatic structure and widely used in textile, paper, food, cosmetics and pharmaceutical industries. Most of the azo dyes used in textile industry are xenobiotic compounds and recalcitrant to conventional degradation process. These dyes cause serious environmental problems because of their carcinogenic nature and reduced penetration of light in aquatic environment. In the present study, the efficiency of the two bacterial cultures on degradation of three different toxic azo dyes (acid, direct and reactive azo dyes) were analysed. The bacterial strains used in this study are Escherichia coli and Pseudomonas putida. To increase the degradation potential, the organisms were acclimatized to the dye environment for sufficient period by gradually decreasing the nutrient broth concentration and increasing the dye concentration so that it can effectively degrade dye rich textile effluent. The effect of concentration of dye, pH, temperature and agitation was studied to determine the optimal conditions for effective decolourisation and degradation. FT-IR and UV spectral analysis were performed to confirm the biodecolourisation.