Obtaining aromatic compounds through lignin oxidation with laccase immobilized in alginate

Ayerim Domínguez-González, Rosa Hernández-Soto, J. Manuel Salgado-Román, A. Nelly Ardila-Arias, J. Alfredo Hernández-Maldonado

Research output: Contribution to journalArticlepeer-review

Abstract

© Agrociencia, 2018. Lignin is an abundant biopolymer in nature; because of its polymeric structure, it is a potential source of aromatic compounds with high added value in the chemical, food and pharmaceutical industries. Lignin can be used with chemical and biological procedures that depolymerize it in a gradual and selective manner. Peroxidases and laccases are enzymes used as oxidizing agents in processes of oxidative depolymerization; however, the use of H2O2 as secondary electron acceptor to increase the oxidizing effect of immobilized laccase is not reported so far. The objective of this study was to evaluate the catalytic capacity of laccase (1.25 mUI) immobilized in alginate pearls, with a particle diameter (Dp) of 3 mm, in order to obtain aromatic compounds from lignin oxidation. The reactions were kept with agitation and controlled temperature, the pH varied and H2O2 was used as secondary electron acceptor. The experimental design was factorial 3 x 4: three pH values (5.8, 6.5 and 8.6) and four concentrations of H2O2 (25, 50, 75 and 100 mM); the trials were performed in triplicate. ANDEVA was carried out with the data as well as means comparison tests (Tukey, p≤0.05). The highest conversion of lignin to aromatic compounds was obtained with a pH of 8.6: benzoic acid (63.5 %), vanillic acid (25 %) and vanillin (11.5 %). The immobilizing support for the enzyme was disintegrated and dissolved in the medium in the reactions catalyzed with a pH over 7.0. The results allow suggesting that the degree of lignin depolymerization with immobilized laccase depends directly on the concentration of H2O2 and the medium's pH.
Original languageAmerican English
Pages (from-to)191-202
Number of pages170
JournalAgrociencia
StatePublished - 1 Feb 2018

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