Textile Dye Decolorizing Synechococcus PCC7942 Engineered With CotA Laccase.

Area of Science:

• Synthetic biology
• Microbial biotechnology
• Enzyme engineering

Background:

• Cyanobacteria are efficient phototrophs, ideal for microbial cell factories due to their ability to utilize sunlight and CO2.
• Heterologous expression of enzymes in cyanobacteria offers a sustainable route for producing valuable compounds.
• The Bacillus subtilis CotA laccase is an industrially relevant enzyme with potential applications in biodegradation.

Purpose of the Study:

• To engineer Synechococcus elongatus PCC7942 for heterologous expression of Bacillus subtilis CotA laccase.
• To compare the performance of strains with laccase integrated into different neutral genomic sites (NS I vs. NS II).
• To evaluate the potential of engineered strains as microbial cell factories for dye biodegradation.

Main Methods:

• Synthetic biology approaches were used to construct two recombinant Synechococcus elongatus PCC7942 strains.
• The CotA laccase gene was integrated into neutral site I (PCC7942-NSI-CotA) and neutral site II (PCC7942-NSII-CotA).
• Growth rates, laccase enzymatic activity (using ABTS and syringaldazine), and dye decolorization capabilities were assessed.

Main Results:

• The PCC7942-NSII-CotA strain exhibited a superior growth rate and higher enzymatic activity compared to PCC7942-NSI-CotA.
• The PCC7942-NSII-CotA strain effectively decolorized anthraquinonic-, azo-, and indigoid-type dyes within 7 days.
• The presence of the redox mediator ABTS did not influence the dye degradation efficiency.

Conclusions:

• Genomic integration site significantly impacts heterologous gene expression and enzyme activity in Synechococcus elongatus.
• The engineered PCC7942-NSII-CotA strain is a promising microbial cell factory for broad-spectrum dye biodegradation.
• This study highlights the potential of cyanobacteria for developing sustainable biodegradation solutions.