Influence of very low doses of mediators on fungal laccase activity - nonlinearity beyond imagination

Elzbieta Malarczyk,Anna Jarosz-Wilkolazka,Janina Kochmanska-Rdest

doi:10.1186/1753-4631-3-10

Elzbieta Malarczyk, Anna Jarosz-Wilkolazka + Show 1 more

Open Access

https://doi.org/10.1186/1753-4631-3-10

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Abstract

Laccase, an enzyme responsible for aerobic transformations of natural phenolics, in industrial applications requires the presence of low-molecular substances known as mediators, which accelerate oxidation processes. However, the use of mediators is limited by their toxicity and the high costs of exploitation. The activation of extracellular laccase in growing fungal culture with highly diluted mediators, ABTS and HBT is described. Two high laccase-producing fungal strains, Trametes versicolor and Cerrena unicolor, were used in this study as a source of enzyme. Selected dilutions of the mediators significantly increased the activity of extracellular laccase during 14 days of cultivation what was distinctly visible in PAGE technique and in colorimetric tests. The same mediator dilutions increased demethylation properties of laccase, which was demonstrated during incubation of enzyme with veratric acid. It was established that the activation effect was assigned to specific dilutions of mediators. Our dose-response dilution process smoothly passes into the range of action of homeopathic dilutions and is of interest for homeopaths.

Highlights

Laccases (EC 1.10.3.2, p-diphenol: dioxygen oxidoreductases) are multi-copper proteins that use molecular oxygen to oxidize various phenolic and non-phenolic aromatic compounds by a radical-catalyzed reaction mechanism
They can enhance laccase activity by using low molecular compounds which accelerate the catalytic properties of enzyme by improving their affinity of specific radical forms to phenolic biopolymers [3]
Changes in laccase activity in cultures of T. versicolor and C. unicolor in the presence of low doses of mediators Fungal strains were grown for 14 days with the addition of the mediators, ABTS and HBT, diluted serially in 75% ethanol as described in Methods

Summary

Introduction

Laccases (EC 1.10.3.2, p-diphenol: dioxygen oxidoreductases) are multi-copper proteins that use molecular oxygen to oxidize various phenolic and non-phenolic aromatic compounds by a radical-catalyzed reaction mechanism. Molecule of laccase is too large for direct contact with the phenolics present in the inner part of such biopolymers as lignin or the lignocellulose complex, so the process of degradation runs very slowly and needs to cooperate with specific co-catalizators. They can enhance laccase activity by using low molecular compounds which accelerate the catalytic properties of enzyme by improving their affinity of specific radical forms to phenolic biopolymers [3]. At the beginning of this process, non-phenolic lignin particles, rich in methoxylic compounds as veratrate or anisate, are degraded by laccase to phenolic compounds mainly via demethylation and hydroxylation and these processes are accelerated in combination with redox co-catalysts known as mediators (page number not for citation purposes)

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