Biodegradation and Decolorization of Textile Azo Dyes by Paramecium caudatum Isolated from Industrial Wastewater

Azo dyes in textile industry effluent are one of the major toxic contaminants causing a severe threat to life. Bioremediation is the most cost-effective and environmentally beneficial innovative biotechnologically technique used to mitigate dyes’ toxic effects in aquatic environments. The purpose of the present study was to determine the azo dyes degradation potential of a ciliate, Paramecium caudatum, isolated from industrial wastewater. Under optimum conditions, P. caudatum was found to possess a 90.86% decolorizing ability of RR2 (reactive red), 83.06% of RB5 (reactive blue) and 85.43% of LY (Levafix reactive yellow) dyes. The P. caudatum showed maximum growth at 25 °C and pH 7.5 in the presence of azo dyes at a concentration of 20 ppm (0.02 mg/mL). After being exposed to RR2, RB5, and LY azo dyes, the level of GSH in P. caudatum increased for the control i.e., 54, 43, and 23%, respectively. Sequentially, the GSSG level decreased by 26% after treatment with the LY azo dye, while exposure to RR2 and RB5 enhanced the value by more than twofold and by 0.86%. The results for the decolorization and biodegradation of azo dyes indicated that P. caudatum is a potential candidate for the treatment of textile industry effluents.