Degradation of azo dyes by pure and mixed bacterial strains of Pseudomonas, Bacillus, Staphylococcus and Micrococcus strain was studied. These strains grew in nutrient broth supplemented with Indosole Yellow BG, Indosole Black G and Indosole Brilliant Red BAwith specific growth rates of 0.28 h-1 , 0.31 h-1 and 0.44 h-1 , respectively. Very low percentage (i.e. < 5%) of azo dyes was removed in mineral salts medium (MM) by pure bacterial strains. Mixed culture degraded azo dyes not more than 20% in MM medium. The degradation was enhanced when a cosubstrate (i.e. glucose) was supplemented in the MM medium containing azo dyes with bacterial consortia. Decolorisation of over 95% of azo dyes with mixed culture was observed when glucose was added with azo dyes in MM medium. Different concentrations of azo dyes (i.e. 10 mg/L and 20 mg/L) were degraded in MM medium supplemented with the same concentration of glucose with almost similar degradation rates.
