(188e) Complete Mineralization of Sulphonated Azo Dyes Using Bacterial Consortia

Azo dyes are widely used in a number of industries such as textile, food, cosmetics, paper, etc. About 60–70% of more than 10, 000 dyes used in the textile industry are azo dyes. Azo dyes production is around 50% of total dye manufactured annually. These compounds have an azo bond (R1–N=N–R2), where R1 and R2 are aromatic groups. During their synthesis and use, large quantities of dyes are lost in waste discharges and domestic wastewaters, thus, leading to surface and ground water pollution.

The aim of the current study was to elucidate the genetic factors responsible for azo dyes degradation and complete mineralization by microbial consortia. These consortia were isolated and characterized (TJ-1 and TJ-2) by 16 S rRNA technique. Azo dyes cannot be easily degraded under aerobic conditions. Nonetheless, it has been shown that the azo bond was reduced anaerobically, which caused color removal. Aromatic amines were obtained from the cleavage of the azo bond. These amines are carcinogenic compounds and are quite stable in anaerobic environments and further mineralization of these compounds was achieved mainly under aerobic conditions. Plasmid curing experiments were performed and it was observed that the genes encoding the enzyme for azo bond reduction were plasmid encoded while the genes encoding for enzymes necessary for mineralization of aromatic amines were chromosomally encoded.