Enhanced delignification of mixed wood pulp by Aspergillus fumigatus laccase mediator system

Abstract

An environmentally sound biobleaching to get high quality paper pulp from mixed wood pulp was attempted employing laccase from Aspergillus fumigatus VkJ2.4.5 for lignin removal. Laccase treatment was performed in the presence of a mediator N-hydroxybenzotriazole (HBT, 1.5% w/w), resulting into notably higher level of delignification of the pulp. Enzyme at 10 Ug -1 of pulp at 50°C, pH 6.0, for 2 h with a pulp consistency of 10% was found suitable for enabling maximum decrease in the kappa number. The kappa number and yellowness decreased by 14 and 4% whereas ISO brightness improved by 7%. The presence of a characteristic peak at 280 nm indicated the presence of lignin in the effluent during biobleaching. Analysis of FTIR spectra of residual lignin revealed characteristic modifications following enzymatic bleaching by laccase mediator system (LMS). Variations in morphology and crystallinity of pulp were evaluated by scanning electron microscopy and X-ray diffraction analysis.

Enhancement of fermentable sugars production from oil palm empty fruit bunch by ligninolytic enzymes mediator system

“…The effect of laccase mediator system with HBT and ABTS on OPEFB residual Klason lignin was performed. These two mediators are the most effective laccase mediator reported based on several studies in various applications (Bourbonnais et al, 1995;Srebotnik and Hammel, 2000;Vivekanand et al, 2008). Fig.…”

Optimization of laccase production and its application in delignification of biomass

“…revealed the mechanism of lignin degradation and its association among ligninolytic enzymes activities formed by fungal cultures (Liew et al 2011). The enzymatic treatment of wood pulp with Aspergillus fumigates laccase mediator system showed rougher surface indicating the process of peeling with more exterior fibrillation (Vivekanand et al 2008). Similar structural and chemical variations were observed in Parthenium sp.…”

“…Aspergillus fumigatus laccase treatment was done in the presence of a mediator N-hydroxybenzotriazole which results in a notable high level of delignification of the pulp. The author reported the appearance of new strong peak at 1720 cm -1 in enzyme-treated pulp (Vivekanand et al 2008). The delignification efficiency by laccase from Peniophora sp.…”

“…Lignin is a highly complex irregular branched three-dimensional polyphenolic polymer consisting of different functional entities like phenyl propanoid units of coniferyl, sinapyl and p-coumaryl alcohols. Functional groups such as phenolic hydroxyl, benzylic hydroxyl and carbonyl moieties were linked to lignin backbone and phenyl propanoid, thereby making them more complex (Vivekanand et al 2008). Lignin contributes to the structural integrity and stability of plant cell walls and resists the enzymatic hydrolysis of hemicellulose.…”

Studies of enzymatic oxidation of TMP-fibers and lignin model compounds by a Laccase–Mediator-System using different 14C and 13C techniques

“…Mediators like 1-hydroxybenzotriazole, acetosyringone, and syringaldehyde were successfully adopted in combination with laccases in the biochemical bleaching of paper pulp and in the degradation of textile fibers. In contrast, the Mediator p-coumaric acid, for example, was less suitable for such applications (Moreira et al 1998;Pandey et al 2000;Lund and Felby 2001;Camarero et al 2004;Chakar and Ragauskas 2004;Rochefort et al 2004;Hakala et al 2005;Ibarra et al 2006;Camarero et al 2007;Gutiérrez et al 2007;Vivekanand et al 2008). A positive effect of the Mediator 4-hydroxy benzoic acid (HBA) in the modifying of paper is described by Chandra et al (2004).…”