A potential bacterial strain PMS82, capable of degrading an azo dye Acid orange as a sole source of carbon was isolated from common effluent treatment plant of Ankleshwar, India. The 16S rDNA sequence and phenotypic characteristics indicated that an isolated organism as Bacillus megaterium PMS82. This strain exhibited complete decolorization of Acid orange (100 mg/L) within 16 h, while maximally it could decolorize 800 mg/L of dye within 38 h with 73% decolorization under static condition. For color removal, the most suitable pH and temperature were pH 6.0-9.0 and 25-40C respectively. The organism has shown more than 70% decolorization activity against five structurally different azo dyes within 38 h and tolerates high salt concentration up to 2% (w/v) respectively with more than 90% decolorization. UV-Visible absorption spectra before and after decolorization suggested that decolorization was due to biodegradation and was further confirmed by FT-IR spectroscopy. Overall results indicating the effectiveness of the strain PMS82 explored for the treatment of common effluent treatment plants containing various azo dyes. To our knowledge, this could be the first report on biodegradation of Acid oragne by Bacillus megaterium PMS82.

biodegradation, decolorization, bacillus megaterium, acid orange, textile azo dye