Laccase-Producing White-Rot Fungus Lacking Lignin Peroxidase and Manganese Peroxidase

Abstract

This paper presents an overview of phenoloxidases involved in lignin degradation with a particular focus on laccase. To investigate the role of laccase in lignin degradation, Pycnoporus cinnabarinus was identified as an excellent organisms for further study. It produces only one isoelectric form of laccase and yet degrades lignin fast and extensively. We report here on the purification and characterization of the P. cinnabarinus laccase. Laccases are generally considered to have a too low redox potential to attack non-phenolic lignin substrates. This is also true for the laccase from P. cinnabarinus. However, to make up for this deficiency, P. cinnabarinus was found to produce a redox mediator, 3-hydroxy anthranilic acid (3-HAA). Laccase plus the redox mediator, was demonstrated to degrade a non-phenolic lignin model dimer.Lignins constitute the second most abundant group of biopolymers in the biosphere; thus, their biodégradation occupies an important position in the global carbon cycle. Studies of lignin biodégradation are also of great importance for possible biotechnological applications since lignin polymers are a major obstacle to the efficient utilization of lignocellulosic materials in a wide range of industrial processes (I). The turnover of lignin biomass occurs primarily through the action of white-rot fungi, consequently, this ecological group has received a considerable amount of research attention, as have the enzymatic mechanisms employed by these fungi for the breakdown of lignin.Most of our understanding of the enzymology of lignin biodégradation stems from studies of a single species of white-rot fungus, Phanerochaete chrysosporium. In P. chrysosporium, lignin degradation occurs only after secondary metabolism has been triggered by starvation for nitrogen, sulfur or phosphorus (2). Prodigious production of extracellular phenoloxidases is a characteristic of this ligninolytic metabolism, and was noted even in very early studies of the differences between 0097-6156/96/0655-0130$15.25/0

An acid-stable laccase from Sclerotium rolfsii with potential for wool dye decolourization

“…EDTA up to a concentration of 300 mM showed no effect on SRL1. DDC (I 50 = 1.2 mM) strongly inhibited the enzyme like many other fungal laccases such as from P. cinnabarinus [43], from B. cinerea [44], from Pleurotus ostreatus, from Trametes versicolor [2] and T. hirsuta [45] where the I 50 values were below 1 mM. Among the halogens tested, fluoride was the strongest inhibitor as shown previously in the literature [46].…”

Laccase is essential for lignin degradation by the white‐rot fungus Pycnoporus cinnabarinus

“…Lignin degradation by P. chrysosporium correlates with the secretion of two peroxidases, lignin peroxidase (LiP) and manganese peroxidase (MnP) [2-A]. However, recent studies suggest that in whiterot fungi the combination of laccase (EC 1.10.3.2) with either LiP and/or MnP is a much more common combination of phenoloxidases than the LiP/MnP pattern found in P. chrysosporium [5].…”

Wood production, wood technology, and biotechnological impacts

“…It is much more ubiquitous than LiP and found in a large number of wood-degrading white-rot fungi (e.g. Eggert et al 1996b, Schneegass et al 1997, Gill &Arora 2003, Kamitsuji et al 2004) as well as in ectomycorrhizal fungi , Cairney et al 2003) that may use such enzymes for mobilising nutrients by decomposing organic materials in soil (Bending & Read 1997, Courty et al 2006. The catalytic cycle of MnP in general resembles that of LiP (Fig.…”

“…However, probably only 40% of white-rot fungi possess this enzyme. P. cinnabarinus, Cyathus stercoreus, Dichomitus squalens, and Ceriporiopsis subvermispora for example degrade lignin without any detectable LiP activity (Périé & Gold 1991, Eggert et al 1996b, Jensen et al 1996, Sethuraman et al 1999. LiP contains a heme in the active site (Banci et al 1991, Choinowski et al 1999) and requires hydrogen peroxide to function (Wariishi et al 1990, Ferapontova et al 2006 (Ward et al 2003; Fig.…”