Microbial decolorization of azo dyes by Proteus mirabilis

A bacterium identified as Proteus mirabilis was isolated from acclimated sl udge from a dyeing wastewater treatment plant, This strain rapidly decolori zed a deep red azo dye solution (RED RBN), Features of the decolorizing pro cess related to biodegradation and biosorption were also studied. Although P. mirabilis displayed good growth in shake culture, color removal was best in anoxic static cultures. For color removal, the optimal pH and temperatu re were 6.5-7.5 and 30-35 degrees C, respectively, The organism exhibited a remarkable color removal capability, even at a high concentration of azo d ye. More than 95% of azo dye was reduced within 20 h at a dye concentration of 1.0 g L-1. Decolorization appears to proceed primarily by enzymatic red uction associated with a minor portion, 13-17%, of biosorption to inactivat ed microbial cells.