Biodegradation and decolorization of Reactive Red 2 azo dye by Paramecium jenningsi and Paramecium multimicronucleatum in industrial wastewater

Azo dyes are widely used in textile industries in variety of processes. Azo dyes are generally considered as xenobiotic chemicals because of their recalcitrant nature against biodegradation processes. However, in recent years, it has been considered that under specific environmental conditions many microorganisms are capable of converting these toxic azo dyes to non-colored compound or even completely mineralize them. The perspective of present study was to evaluate the decolorizing efficiency of newly isolated Paramecium species in textile industrial wastewater containing azo dyes. This efficiency was assessed by determining the level of stress biomarkers such as GSH, GST, CAT, SOD, and GPx in the ciliates. Under optimum conditions of temperature and pH, RR2 azo dyes have 90.86 and 90.37% decolorization by P. jenningsi and P. multimicronucleatum, respectively. The azo dye degraded products were analyzed by using Fourier transformed infrared spectroscopy (FTIR). Morphology of Paramecium species was analyzed under light microscope after exposure to azo dye. GSH contents were significantly decreased while activities of antioxidant enzymes such as GST, CAT, SOD, and GPx were significantly increased as compared to control. As a result, Paramecium seems to be potentially useful for bioremediation of textile-dying industry effluents.