[Decoloration and bioaugmentation on azo dye by immobilized genetically engineered strain]

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Treatment

Background:

• Azo dyes are widely used in industries, posing environmental challenges due to their persistence.
• Bioaugmentation using genetically engineered microorganisms offers a promising strategy for dye decolorization.

Purpose of the Study:

• To investigate the decolorization of azo dye Acid Red GR using immobilized genetically engineered Escherichia coli JM109 (pGEX-AZR).
• To evaluate the performance of bioaugmentation in anaerobic sequencing batch reactors (SBRs) for continuous dye removal.

Main Methods:

• Immobilization of engineered Escherichia coli JM109 (pGEX-AZR) on macroporous foam carriers.
• Kinetic analysis of Acid Red GR decolorization using the Andrews model.
• Continuous operation of anaerobic SBRs with bioaugmentation for 32 days.
• Microbial community analysis using Ribosomal Intergenic Spacer Analysis (RISA).

Main Results:

• Decolorization kinetics followed the Andrews model with specific parameters determined (µmax,c = 49.2 mg/(g·h), Kc = 710.43 mg/L, Kic = 681.62 mg/L).
• Bioaugmented anaerobic SBRs demonstrated enhanced tolerance to dye shock loads and achieved 90% Acid Red GR removal.
• RISA confirmed the stable coexistence of introduced engineered microorganisms and the native sludge community.

Conclusions:

• Immobilized genetically engineered Escherichia coli is effective for azo dye decolorization.
• Bioaugmentation significantly improves the efficiency and stability of dye removal in wastewater treatment.
• The engineered microbial consortium maintained stability within the sludge system, indicating successful long-term application.