ISOLATION OF DYE DEGRADING MICROORGANISM

Bacillus species isolated from soil contaminated with untreated textile mill effluent utilized an Azo dye (Golden Yellow HER) as sole source of carbon & nitrogen. Highest decolourization (100%) was obtained by isolated Bacillus species for Golden Yellow dye. The Azo-nitrogen of the dye substrates provides nitrogen requirement of the organism in cultures in absence of nitrogen. Decolourization of dyes is a reduction process which requires redox equivalents (electron donors) that transfer electrons to the chromographic group dyes. Nitrate (NO3~) has higher oxidation character compared to the chromophoric group dyes. The result obtained was attributed to competition between (NO3~) and the chromophoric group for the redox equivalents, which result in preferential reduction of (NO3") relative to the chromophoric group. Decolourization was accompanied by increase in total viable count. Ring opening of the aromatic moiety of the dyes produce the carbon source for the organism. The results have shown the potential of the isolated Bacillus species under nitrate-starvation condition for the treatment of dye wastewater.