Simultaneous decolorization of reactive Orange M2R dye and reduction of chromate by Lysinibacillus sp. KMK-A

Azo dyes constitute the largest and diverse group of dyes, widely used in number of industries that are contributing toward organic and inorganic load of effluent treatment. In the present study, Lysinibacillus sp. KMK-A was able to effectively decolorize Orange M2R dye up to 2000 mg l(-1) (Vmax of 19.6 mg l(-1) h(-1) and Km of 439 mg l(-1)) and reduce Cr(VI) up to 250 mg l(-1) (Vmax of 3.6 mg l(-1) h(-1) and Km 28.3 mg l(-1)). It also has an ability of simultaneous decolorization of Orange M2R dye (200-1000 mg l(-1)) with reduction of Cr(VI) (50-200 mg l(-1)). Significant reduction in total organic carbon content, chemical and biological oxygen demand along with spectroscopic and chromatographic analysis confirmed the biotransformation of Orange M2R. Involvement of enzymes namely azoreductase and chromate reductase was observed during biotransformation. The phyto and geno toxicity studies demonstrated that metabolites of dye degradation were non-toxic. Higher tolerance with simultaneous decolorization and detoxification of azo dyes in presence of Cr(VI) makes Lysinibacillus sp. KMK-A, a potential candidate for eco-friendly remediation of metal contaminated dye effluents.