A bacterium identified as Proteus mirabilis was isolated from acclimated sludge from a dyeing wastewater treatment plant. This strain rapidly decolorized a deep red azo dye solution (RED RBN). Features of the decolorizing process 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 temperature were 6.5–7.5 and 30–35°C, respectively. The organism exhibited a remarkable color removal capability, even at a high concentration of azo dye. 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 reduction associated with a minor portion, 13–17%, of biosorption to inactivated microbial cells.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received 06 January 1999/ Accepted in revised form 22 April 1999
Rights and permissions
About this article
Cite this article
Chen, KC., Huang, WT., Wu, JY. et al. Microbial decolorization of azo dyes by Proteus mirabilis . J Ind Microbiol Biotech 23, 686–690 (1999). https://doi.org/10.1038/sj.jim.2900689
Issue Date:
DOI: https://doi.org/10.1038/sj.jim.2900689