Peculiarities of brown-rot fungi and biochemical Fenton reaction with regard to their potential as a model for bioprocessing biomass

Abstract

This work reviews the brown-rot fungal biochemical mechanism involved in the biodegradation of lignified plant cell walls. This mechanism has been acquired as an apparent alternative to the energetically expensive apparatus of lignocellulose breakdown employed by white-rot fungi. The mechanism relies, at least in the incipient stage of decay, on the oxidative cleavage of glycosidic bonds in cellulose and hemicellulose and the oxidative modification and arrangement of lignin upon attack by highly destructive oxygen reactive species such as the hydroxyl radical generated non-enzymatically via Fenton chemistry [Formula: see text]. Modifications in the lignocellulose macrocomponents associated with this non-enzymatic attack are believed to aid in the selective, near-complete removal of polysaccharides by an incomplete cellulase suite and without causing substantial lignin removal. Utilization of this process could provide the key to making the production of biofuel and renewable chemicals from lignocellulose biomass more cost-effective and energy efficient. This review highlights the unique features of the brown-rot fungal non-enzymatic, mediated Fenton reaction mechanism, the modifications to the major plant cell wall macrocomponents, and the implications and opportunities for biomass processing for biofuels and chemicals.

Mode of action of brown rot decay resistance in modified wood: a review

“…This can be detected in the outer parts of the cell wall based on increases in the carbonyl group content and demethylation (Eriksson et al 1990;Filley et al 2002;Fackler et al 2010). Lignin modification contributes to the formation of microcapillary pathways that allow enzymes to penetrate the wood cell wall (Arantes et al 2012). It has been suggested that fragments of oxidatively remodeled lignin in brown-rotted wood may contribute to the formation of hydroxyl radicals (Xu and Goodell 2001;Filley et al 2002;Goodell et al 2006) as an integral part of the redox processes.…”

“…The first signs of brown rot decay are visible in the outer regions of the cell wall, that is, in the middle lamella, S1, and the outer parts of S2 (Irbe et al 2006;Fackler et al 2010 Goodell et al (1997), Arantes et al (2012), and Baldrian and Valaskova (2008). HQ, hydroquinone; MF, microfibrils; Q, quinone.…”

“…Details of polysaccharide degradation by brown rot are summarized in Figure 1, which is based mainly on studies by Goodell et al (1997), Baldrian and Valaskova (2008), and Arantes et al (2012). Brown rot fungi degrade polysaccharides via oxidative and enzymatic activities (Eriksson et al 1990;Eaton and Hale 1993;Goodell 2003;Aro et al 2005;Fackler et al 2010).…”

“…Aro et al (2005) reviewed the transcriptional regulation of enzymes involved in the breakdown of cell wall biopolymers by filamentous fungi. The biochemical mechanisms that underlie nonenzymatic degradation of wood were recently summarized in a comprehensive review (Arantes et al 2012). However, general comparative reviews are not available in terms of the modes of action of different wood modification methods.…”

Furfurylated wood: impact on Postia placenta gene expression and oxalate crystal formation

“…A review of the degradation of cellulose by basidiomycetous fungi is provided by Baldrian and Valaskova (2008), and brown-rot decay mechanisms are more currently reviewed by Arantes et al (2012) and Arantes and Goodell (2014). Brown-rot fungi have also a nonenzymatic system as a tool: the chelator-mediated Fenton system, that rapidly depolymerises the polysaccharides and lignin in early stages of biodegradation (Goodell et al 1997a;Arantes et al 2011;Eastwood et al 2011).…”