Fungal laccases: Induction and production

 

B. Bertrand, F. Martínez-Morales and M. R. Trejo-Hernández

 

 

Fungal laccases are phenol oxidases that have been extensively studied due to their relevance in diverse industrial applications including paper whitening, color reduction, elimination of phenolic compounds in wine, detoxification of polluted environments, revaluation of industrial wastes and water treatment. The principal difficulties in the use of these enzymes on an industrial scale are the cost of production and limitations on operation conditions (low stability and low catalytic activity). Over the last few decades, a variety of strategies have been evaluated to increase the productivity and improve the biochemical properties of these enzymes. The identification of inducers and the mechanisms by which gene expression is regulated is crucial for efforts to increase laccase production in fungi. Laccase gene transcription is regulated by various carbon and nitrogen sources, the presence of metal ions, the addition of diverse aromatic compounds related to lignin or its derivatives (phenolic and/or non-phenolic), and even the presence of other microorganisms. Although abundant information is available about the biochemical properties and kinetic parameters of laccases, it is difficult to compare different laccases due to the diversity of laccase producing strains, isoforms, laccase substrates, inducers and operating conditions. This review discusses the literature on the induction and production of fungal laccases.