Biodegradation of azo dye Direct Orange 16 by Micrococcus luteus strain SSN2

In the present study, the decolorization and degradation of azo dye Direct Orange 16 (DO-16) by a potential bacterial isolate isolated from textile effluent were evaluated. Through 16S rRNA sequence matching, the potential isolate was identified as Micrococcus luteus strain SSN2. The effects of various factors (pH, temperature, salt and dye concentration) on decolorization were investigated. The strain SSN2 had the ability to decolorize DO-16 with 96 % efficiency at pH 8, 37 A degrees C and 3 % NaCl in a short time of 6 h under static conditions. DO-16 decolorization was assessed by UV-Vis spectrophotometer with gradual decrease of dye peak intensity at 430 nm (lambda (max)). Analytical techniques (thin-layer chromatography, Fourier transform infrared spectroscopy and high-performance liquid chromatography) further confirmed that biodegradation of DO-16 was due to reduction of the azo bond. The phytotoxicity assay (with respect to seeds of Vigna mungo and Vigna radiata) demonstrated the less toxic nature of the DO-16-degraded products compared to the toxic azo dye.