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Functional Characterization of Laccase Isozyme (PolCC1) from the Edible Mushroom Pleurotus ostreatus Involved in Lignin Degradation in Cotton Straw

Summary

This research examined how mushrooms break down tough plant materials like cotton stalks using special enzymes called laccases. The scientists identified optimal conditions for this process and studied a specific gene (Lacc1) that helps produce these enzymes. Understanding this process has important real-world applications: • Could help develop more efficient ways to recycle agricultural waste like cotton stalks • May lead to more environmentally friendly methods for processing wood and paper products • Could improve the production of biofuels from plant materials • Helps reduce agricultural pollution by providing alternatives to burning crop residues • Could enhance mushroom cultivation on agricultural waste materials

Background

Laccase is a multi-copper oxidase that catalyzes the oxidation of various phenolic and non-phenolic substrates associated with lignin structure while reducing oxygen to water. Due to its wide range of natural substrates, laccase has applications in industrial and biotechnological fields including fiber properties improvement, antibiotic degradation, fuel production, environmental pollutant detoxification, lignin stabilization, and pulp bleaching. Most known laccases originate from fungi, especially white rot fungi capable of lignin degradation.

Objective

To optimize laccase producing conditions for Pleurotus ostreatus on cotton straw medium and investigate the role of the Lacc1 gene in cotton straw lignin degradation through construction and analysis of an overexpression strain.

Results

The optimal culture conditions for highest lignin degradation were: cotton straw particle size of 0.75 mm, solid-liquid ratio of 1:3, 0.25 g/L Tween, and 26°C incubation temperature. Two overexpression strains (OE L1-1 and OE L1-4) showed 12.08- and 33.04-fold increased Lacc1 expression respectively. The overexpression strains demonstrated enhanced lignin degradation rates and structural analysis revealed the Lacc1 gene accelerated G-unit lignin degradation and was involved in β-O-4 linkage cleavage and lignin unit demethylation.

Conclusion

The study successfully optimized conditions for laccase production and lignin degradation by P. ostreatus on cotton straw. Functional characterization of the Lacc1 gene demonstrated its important role in lignin degradation through specific structural modifications. These findings advance understanding of fungal lignin degradation mechanisms and may help improve biodelignification efficiency.
  • Published in:International Journal of Molecular Sciences,
  • Study Type:Laboratory Research,
  • Source: 10.3390/ijms232113545
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