Decolorization of various azo dyes by bacterial consortium

This study was taken up to enrich and isolate bacterial strains capable of decolorizing azo dyes present in soil/sludge samples collected from waste disposal sites of local textile industries. Four bacterial isolates identified as Bacillus cereus (BN-7), Pseudomonas putida (BN-4), Pseudomonas fluorescence (BN-5) and Stenotrophomonas acidaminiphila (BN-3) capable of completely decolorizing C.I. Acid Red 88 (AR-88), were used to develop consortium designated HM-4. The concerted metabolic activity of these isolates led to complete decolorization of AR-88 (20 mg L-1) in 24 h, whereas individual cultures took more than 60 h to achieve complete decolorization of the added dye. The consortium was screened for its ability to decolorize different concentrations of other commonly used azo dyes in addition to AR-88. It was able to decolorize 78% of C.I. AcidRed 88, 99% of C.I. Acid Red 119, 94% of C.I. Acid Red 97, 99% of C.I. Acid Blue 113 and 82% of C.I. Reactive Red 120 dyes at an initial concentration of 60 mg L-1 of mineral salts medium (MSM) in 24 h. This consortium will be used to develop bioreactor for achieving effective decolorization of textile industry effluent containing mixture of azo dyes. (c) 2004 Elsevier Ltd. All rights reserved.