Microbial decolorization of azo dyes by Proteus mirabilis

Area of Science:

• Environmental microbiology
• Bioremediation of industrial effluents

Background:

• Dyeing wastewater poses environmental challenges due to persistent azo dyes.
• Effective microbial strains are needed for decolorization and detoxification of textile effluents.

Purpose of the Study:

• To isolate and identify a bacterial strain capable of decolorizing azo dyes.
• To investigate the decolorization efficiency and mechanism of the isolated strain.
• To determine optimal conditions for azo dye decolorization by the identified bacterium.

Main Methods:

• Isolation of bacteria from acclimated sludge in a dyeing wastewater treatment plant.
• Cultivation of Proteus mirabilis in shake and static cultures.
• Optimization of pH, temperature, and dye concentration for decolorization.
• Analysis of biodegradation and biosorption contributions to color removal.

Main Results:

• Proteus mirabilis rapidly decolorized a red azo dye (RED RBN).
• Optimal decolorization occurred in anoxic static cultures at pH 6.5-7.5 and 30-35°C.
• Over 95% azo dye removal was achieved within 20 hours at 1.0 g L⁻¹ dye concentration.
• Decolorization was primarily via enzymatic reduction (83-87%) with minor biosorption (13-17%).

Conclusions:

• Proteus mirabilis is a highly effective agent for azo dye decolorization in industrial wastewater.
• The bacterium's enzymatic reduction capability offers a promising bioremediation strategy.
• Optimized conditions enhance the efficiency of microbial azo dye removal.