Eco-friendly decolorization and degradation of reactive yellow 145 textile dye by Pseudomonas aeruginosa and Thiosphaera pantotropha

Dyes are toxic and inherently resistant to microbial degradation. In this study, decolorization and degradation of textile dye reactive yellow 145 (RY145) were evaluated using pure bacterial strains Pseudomonas aeruginosa (RS1) and Thiosphaera pantotropha ATCC 35512. In nutrient broth under static condition, complete decolorization of 50 mg L-1 RY145 could be achieved within 96 h and 72 h, for Pseudomonas aeruginosa (RS1) and Thiosphaera pantotropha, respectively. In contrast, under shaking condition both the cultures could achieve only 50% decolorization in 96 h. Treatment under sequential static and shaking condition resulted in complete decolorization and 65% mineralization after 96 h. Higher dye concentration in excess of 100 mg L-1 and 50 mg L-1 decreased the extent of dye mineralization in Pseudomonas aeruginosa and Thiosphaera pantotropha, respectively. Even with the repetitive addition of the dye, both the strains were capable of decolorizing the dye. Acclimatized cultures showed 54% decolorization of RY145 in mineral media (MM) even in the absence of a readily degradable external carbon source. Amongst various individual carbon and nitrogen sources, maximum decolorization was observed in MM supplemented with peptone as carbon and nitrogen source at pH 7 under static condition.