Fungal laccases: induction and production

Lacasas fungales: inducción y producción

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

Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos. Av. Universidad No. 1001, Col. Chamilpa, C.P. 62209 Cuernavaca Morelos, México. * Corresponding author. E-mail: mtrejo@uaem.mx Tel. 52-777 3297057; Fax: 52-777 3297030.

Abstract

Fungal laceases are phenol oxidases that have been extensiveiy 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 rtrategies 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 microorgamsms. 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.

Keywords: laccase isoforms, induction, laccase regulation, laccase production.

Resumen

Las lacasas fúngicas son oxidasas fenólicas ampliamente estudiadas por su relevancia en diversas aplicaciones industriales, incluyendo el blanqueo de papel, reducción de color, eliminación de compuestos fenólicos en el vino, la biorremediación de ambientes contaminados, en la revalorización de residuos industriales y el tratamiento de aguas residuales. Las dificultades en el uso de lacasas a escala industrial son el costo de la producción y las limitaciones en las condiciones de operación (baja es tabilidad y actividad catalítica). En la última decada, se han evaluado diferentes estrategias que permiten un aumento de la productividad y la mejora de sus propiedades bioquímicas. Por ello, la identificación de los inductores y de los mecanismos implicados en la regulación de la expresión génica es crucial para el aumento de la producción de lacasa en los hongos. La transcripción de genes de lacasa está regulada por diferentes fuentes de carbono y nitrógeno, la adición de compuestos fenólicos y no fenólicos, la presencia de iones metálicos, y la interacción con otros organismos. Aunque existe información acerca de las propiedades bioquímicas y parámetros cinéticos de las lacasas, es difícil compararlos debido a la diversidad de cepas, número de isoformas, sustratos e inductores y condiciones de operación utilizadas. En esta revisión, se discuten los aspectos generales de la inducción y producción de lacasas fúngicas.

Palabras clave: isoformas de lacasa, inducción, regulación, producción.

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