Microbial use for azo dye degradation-a strategy for dye bioremediation.

Azo dyes are aromatic compounds with one to many -N=N- groups as well as the leading class of synthetic dyes utilised in commercial solicitations. Azo dyes, released in the environment through textile effluents, have hazardous effects on the aquatic as well as human life. Their persistence and discharge into the environment are becoming a global concern; thus, the remediation of these contaminants has acquired great attention. The current review comprehensively discusses some of the main aspects of biodegradation of azo dyes. A variety of physicochemical approaches has already been utilised for treatment of textile effluents counting filtration, coagulation and chemical flocculation. Though these conventional techniques are effective, yet they are lavish and also comprise formation of concentrated sludge that makes a secondary disposal problem. In this regard, microbial usage is an effective, economical, bio-friendly and ecologically benign approach.

Degradation of azo dyes by Alcaligenes aquatilis 3c and its potential use in the wastewater treatment.

In the present study, Alcaligenes aquatilis was found to decolorize 82% Synazol red 6HBN after incubation of 4 days at 37 °C and pH 7. Maximum decolorization was found under static conditions by using saw dust and yeast extract as carbon and nitrogen source. It also showed promising potential to decolorize mixture of multiple dyes at a rate of more than 86% in 5 days. Decolorization of dye had positive influence on the growth of bacterium as growth rate was increased along with decolorization. The cleavage of azo bond was confirmed through TLC, HPLC and GC-MS analysis. The dye metabolites produced during bacterial treatment are linked to various pathways including ATP synthesis process. The absence of peaks of wavelength 1612/cm and 1532/cm in bacterially treated FTIR sample demonstrated the cleavage of azo bond. Microbial growth in decolorized dye wastewater shows that bacterially decolorized wastewater is unharmful for the growth of micro-flora. The high decolorization ability of A. aquatilis 3c to convert toxic azo dyes into useful end products may find potential applications in the environmental biotechnology.