Biodegradation of textile dye Direct Blue 71 using root nodulating Rhizobium sp.

Textile dye pollution is an issue of environmental concern.. Though microbes have been widely explored for their dye degrading abilities, little work has been reported using root nodulating bacteria. In the present study, an attempt has been made to use a non-pathogenic, nitrogen fixing soil bacteria for biodegradation of textile dye, Direct Blue 71 (DB71). The 11 isolates of Rhizobium showed potential to decolourize the triazo dye DB71. Of these, isolate TUR2 (GenBank accession no. JF820124) showed the highest (95%) ability to decolourize the dye. Over expression of oxidative and reductive enzymes in the presence of the dye indicated their role in degradation which was confirmed using analytical techniques like HPLC, FTIR and GC-MS. Phytotoxicity studies have shown these dye metabolites to be non-toxic. Results of this study indicate potential use of Rhizobium sp. in biodegradation of textile dye, and suggest further investigation towards developing a dual technology of biofertilization coupled with bioremediation.