[Laccase and tyrosinase activities in lichens]

Area of Science:

• Mycology
• Biochemistry
• Environmental Science

Background:

• Lichenized ascomycetes are symbiotic microorganisms with diverse metabolic capabilities.
• Phenoloxidases are enzymes involved in the oxidation of phenolic compounds.
• The role of phenoloxidases in lichen metabolism and ecological functions is not fully understood.

Purpose of the Study:

• To investigate the presence and activity of phenoloxidases in different taxonomic groups of lichenized fungi.
• To determine the types of phenoloxidase activities (laccase, tyrosinase) present in lichens.
• To explore the potential role of these enzymes in phenolic metabolism and soil formation.

Main Methods:

• Enzyme assays were performed on various lichen species from the orders Peltigerales and Lecanorales.
• Laccase and tyrosinase activities were quantified in both intact and disrupted thalli.
• The effect of rehydration and desiccation-rehydration cycles on enzyme activity was examined.

Main Results:

• Phenoloxidase activity, including both laccase and tyrosinase, was detected in Peltigerales lichens.
• Lecanorales lichens exhibited only laccase activity, at significantly lower levels than Peltigerales.
• Water-soluble phenoloxidases were found in Peltigerales, with activity increasing upon rapid rehydration and stimulation by desiccation-rehydration cycles.

Conclusions:

• Lichenized fungi, particularly Peltigerales, possess significant phenoloxidase activity.
• These enzymes are likely involved in the phenolic metabolism of lichens.
• Phenoloxidases in lichens may contribute to humus synthesis during primary soil formation, representing a novel geochemical function.