Citrobacter freundii mediated degradation of textile dye Mordant Black 17

One of the important worldwide environmental problems is the improper discharge of colored effluents to aqueous ecosystems which causes acute toxic effects on aquatic flora and fauna. The present study concentrates on efficiency and potentiality of a bacterium isolated from a textile effluent to degrade the azo dye Mordant black 17. Phenotypic characterization and phylogenetic analysis using 16S rRNA sequence indicated that the bacterial strain was Citrobacter freundii. This organism was able to decolorize the azo dye, mordant black 17 (at a concentration of 100 mg L−1) efficiently bringing about 82% and 89% decolourization under shake and static conditions, respectively, at a temperature of 35 °C and at pH 6.5. Instrumental analysis confirmed the presence of naphthoquinone and salicylic acid as break-down products of the dye, indicating that the dye can be completely degraded by this organism.