[Dye decolorization by bacterial laccase Lac15].

Area of Science:

• Environmental Microbiology
• Biotechnology
• Enzyme Engineering

Background:

• Industrial effluents often contain persistent synthetic dyes, posing environmental challenges.
• Laccases are versatile oxidoreductive enzymes capable of degrading a wide range of organic pollutants.
• Marine metagenomic libraries are a promising source for discovering novel enzymes with unique properties.

Purpose of the Study:

• To identify and characterize a novel bacterial laccase from a marine metagenomic library.
• To evaluate the dye decolorization efficiency of the purified recombinant laccase (rLac15).
• To assess the potential industrial applicability of rLac15 in treating dye-containing wastewater.

Main Methods:

• Screening of a marine metagenomic library for laccase activity.
• Cloning, expression, and purification of the identified bacterial laccase (Lac15).
• Enzymatic assays to determine the decolorization of various synthetic azo and anthraquinonic dyes by rLac15, with and without a mediator (methylsyringate).

Main Results:

• A bacterial laccase, designated Lac15, was successfully isolated and characterized.
• Purified rLac15 demonstrated higher decolorization efficiency for azo dyes compared to anthraquinonic dyes.
• rLac15 achieved over 95% decolorization of Acid Red 6B and Reactive Blue 194 at 100 micromol/L concentrations under optimized conditions (45°C, pH 8.5, 1h).
• Significant decolorization (>80%) was observed even at higher dye concentrations (200 micromol/L).
• At room temperature (25°C), rLac15 also showed robust decolorization capabilities within 24 hours.

Conclusions:

• The marine bacterial laccase rLac15 exhibits potent decolorization activity against synthetic azo dyes.
• Optimized conditions enhance the efficiency of rLac15 in dye degradation.
• rLac15 demonstrates stability and effectiveness across a range of dye concentrations and temperatures, indicating strong potential for industrial wastewater treatment.