Bioremediation of Textile Azo Dye Congo Red Using Bacterial Isolates From Textile Waste Water

Abstract

Increasing environmental pollution has compelled the textile industries to investigate into the possible environment-friendly methods of treating industrial waste. Synthetic dyes that are generally used in industries are toxic, mutagenic, carcinogenic and recalcitrant in nature. Microorganisms have the ability to decolorize synthetic dyes used in textile industry for dyeing. Total of nine isolates were selected on the basis of Gram’s reaction, colony characteristics and cell morphology. The samples contained only Gram negative species. All isolates were tested for their ability to decolorize the azo dye Congo red (CR). Further, these isolates were optimized for pH, temperature, aeration and varying medium for maximum decolorization of azo dyes. Differences in structures and complexity of the dye led to varied decolourization of different dyes by the same organism. The selected bacterium showed higher decolorization in microaerophilic condition as compared to aerophilic condition. But the percentage decolorization of CR was almost similar in both Glucose-Peptone-Yeast extract (GPY) medium and Minimal Salt Medium (MSM) with varied time period. At 35o C and pH (7 - 8) the isolated bacteria showed higher decolorization. After the dye decolorization, bands on TLC and UV-visible absorbance spectra showed a maximum absorption peak in the visible area which decreased to a minimum level after 48 h of incubation. This proved that the dye was degraded by the bacteria when compared to the control.