title: Early attack and subsequent changes produced in an industrial lignin by a fungal laccase and a laccase-mediator system: an analytical approach.
abstract: An industrial kraft pine lignin (Indulin AT, KL) was characterized and treated in both aqueous-buffered media and dioxane to water, either with a partially purified laccase from Fusarium proliferatum or with the laccase plus 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic-acid (ABTS) as mediator. The changes in the lignin after different incubation periods were analyzed through the application of high performance liquid chromatography (HPLC), UV-visible (Vis) spectroscopy and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). At the onset of incubation, laccase-treated samples showed a slight polymerization and strong modifications in UV-Vis spectra. Through Py-GC/MS, a decrease in phenolic and methoxy-bearing pyrolysis products was observed, in contrast to an increase in the more oxidized products. After longer incubation periods (48 h) a substantial polymerization was detected by HPLC, along with a decrease in the guaiacyl (G) units. In contrast, the analysis by HPLC of the samples recovered from the laccase-ABTS system (LMS) showed an intense depolymerization, accompanied by a sizeable loss in G units and a decrease in the methyl and ethyl side-chain phenolic compounds. These results provide conclusive evidence of a rapid initial attack of the industrial lignin by laccase and notable modifications in the KL after longer incubation periods with laccase or LMS.
authors.affiliation: Departamento de Microbiología y Biología Celular, Facultad de Farmacia, Universidad de La Laguna, La Laguna, Tenerife, 38206, Spain.
authors.forename: K
authors.initials: K
authors.lastname: González Arzola
authors.forename: O
authors.initials: O
authors.lastname: Polvillo
authors.forename: M E
authors.initials: ME
authors.lastname: Arias
authors.forename: F
authors.initials: F
authors.lastname: Perestelo
authors.forename: A
authors.initials: A
authors.lastname: Carnicero
authors.forename: F J
authors.initials: FJ
authors.lastname: González-Vila
authors.forename: M A
authors.initials: MA
authors.lastname: Falcón
mesh_terms: D052160:Benzothiazoles / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005670:Fusarium / Q000201:enzymology*; D008401:Gas Chromatography-Mass Spectrometry; D042845:Laccase / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism*; D013057:Spectrum Analysis; D013451:Sulfonic Acids / Q000378:metabolism; D013997:Time Factors
chemical_list: D052160:Benzothiazoles; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C076151:Kraft lignin; D008031:Lignin; D042845:Laccase