Mechanisms of wood degradation by brown-rot fungi: chelator-mediated cellulose degradation and binding of iron by cellulose

Acetylation has been shown to delay fungal decay, but the underlying mechanisms are poorly understood. Brown-rot fungi, such as Rhodonia placenta (Fr.) Niemelä, K.H. Larss. & Schigel, degrade wood in two steps, i.e., oxidative depolymerization followed by secretion of hydrolytic enzymes. Since separating the two degradation steps has been proven challenging, a new sample design was applied to the task. The aim of this study was to compare the expression of 10 genes during the initial decay phase in wood and wood acetylated to three different weight percentage gains (WPG). The results showed that not all genes thought to play a role in initiating brown-rot decay are upregulated. Furthermore, the results indicate that R. placenta upregulates an increasing number of genes involved in the oxidative degradation phase with increasing WPG.

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Investigations on Lignin and Lignification. IX. The Relationship Between the Action of Brown Rot Fungi, Cellulose Degradation and Lignin Composition in Bagasse

Journal of the American Chemical Society ◽

10.1021/ja01133a032 ◽

1952 ◽

Vol 74 (13) ◽

pp. 3326-3328 ◽

Cited By ~ 7

Author(s):

George de Stevens ◽

F. F. Nord

Keyword(s):

Cellulose Degradation ◽

Brown Rot ◽

Brown Rot Fungi ◽

Lignin Composition ◽

The Relationship

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Degradation of chemically modified Scots pine (Pinus sylvestris L.) with Fenton reagent

Holzforschung ◽

10.1515/hf-2014-0067 ◽

2015 ◽

Vol 69 (2) ◽

pp. 153-161 ◽

Cited By ~ 5

Author(s):

Yanjun Xie ◽

Zefang Xiao ◽

Carsten Mai

Keyword(s):

Fenton Reaction ◽

Oxidative Degradation ◽

Brown Rot ◽

Fenton Reagent ◽

Wood Degradation ◽

Weight Percentage ◽

Brown Rot Fungi ◽

Minor Losses ◽

Brown Rot Decay ◽

Modified Wood

AbstractThe Fenton reaction is supposed to play a key role in the initial wood degradation by brown rot fungi. Wood was modified with 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and glutaraldehyde (GA) to various weight percentage gains in order to study if these types of modifications are able to reduce wood degradation by Fenton reagent. Veneers modified with higher concentrations (1.2 and 2.0 mol l-1) of both chemicals exhibited minor losses in mass and tensile strength during treatment with Fenton reagent, which shows restrained oxidative degradation by hydroxyl radicals. The decomposition rate of H2O2was lower in the Fenton solutions containing modified veneers than in those containing unmodified controls. More CO2evolved in systems containing unmodified veneers than in systems with modified veneers, indicating that modification protected wood from mineralisation. The reason for the enhanced resistance of modified wood to the Fenton reaction is attributed to impeded diffusion of the reagent into the cell wall rather than to inhibition of the Fenton reaction itself. The results show that wood modification with DMDHEU and GA is able to restrain the degradation of wood by the Fenton reaction and can explain why modified wood is more resistant to brown rot decay.

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Transcriptome analysis of the brown rot fungus Gloeophyllum trabeum during lignocellulose degradation

PLoS ONE ◽

10.1371/journal.pone.0243984 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0243984

Author(s):

Kiwamu Umezawa ◽

Mai Niikura ◽

Yuka Kojima ◽

Barry Goodell ◽

Makoto Yoshida

Keyword(s):

Degradation Mechanism ◽

Enzymatic Saccharification ◽

Japanese Cedar ◽

Brown Rot ◽

Terpene Synthase ◽

Lignocellulose Degradation ◽

Substrate Selectivity ◽

Gloeophyllum Trabeum ◽

Wood Degradation ◽

Brown Rot Fungi

Brown rot fungi have great potential in biorefinery wood conversion systems because they are the primary wood decomposers in coniferous forests and have an efficient lignocellulose degrading system. Their initial wood degradation mechanism is thought to consist of an oxidative radical-based system that acts sequentially with an enzymatic saccharification system, but the complete molecular mechanism of this system has not yet been elucidated. Some studies have shown that wood degradation mechanisms of brown rot fungi have diversity in their substrate selectivity. Gloeophyllum trabeum, one of the most studied brown rot species, has broad substrate selectivity and even can degrade some grasses. However, the basis for this broad substrate specificity is poorly understood. In this study, we performed RNA-seq analyses on G. trabeum grown on media containing glucose, cellulose, or Japanese cedar (Cryptomeria japonica) as the sole carbon source. Comparison to the gene expression on glucose, 1,129 genes were upregulated on cellulose and 1,516 genes were upregulated on cedar. Carbohydrate Active enZyme (CAZyme) genes upregulated on cellulose and cedar media by G. trabeum included glycoside hyrolase family 12 (GH12), GH131, carbohydrate esterase family 1 (CE1), auxiliary activities family 3 subfamily 1 (AA3_1), AA3_2, AA3_4 and AA9, which is a newly reported expression pattern for brown rot fungi. The upregulation of both terpene synthase and cytochrome P450 genes on cedar media suggests the potential importance of these gene products in the production of secondary metabolites associated with the chelator-mediated Fenton reaction. These results provide new insights into the inherent wood degradation mechanism of G. trabeum and the diversity of brown rot mechanisms.

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Enzymatic oxalic acid regulation correlated with wood degradation in four brown-rot fungi

International Biodeterioration & Biodegradation ◽

10.1016/j.ibiod.2012.05.030 ◽

2012 ◽

Vol 75 ◽

pp. 109-114 ◽

Cited By ~ 19

Author(s):

Anne Christine Steenkjær Hastrup ◽

Frederick Green ◽

Patricia K. Lebow ◽

Bo Jensen

Keyword(s):

Oxalic Acid ◽

Brown Rot ◽

Wood Degradation ◽

Brown Rot Fungi

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Lignocellulosic Waste Pretreatment Solely via Biocatalysis as a Partial Simultaneous Lignino-Holocellulolysis Process

Catalysts ◽

10.3390/catal11060668 ◽

2021 ◽

Vol 11 (6) ◽

pp. 668

Author(s):

Justine Oma Angadam ◽

Seteno Karabo Obed Ntwampe ◽

Boredi Silas Chidi ◽

Jun Wei Lim ◽

Vincent Ifeanyi Okudoh

Keyword(s):

Literature Review ◽

Digestive Enzyme ◽

Interdisciplinary Approach ◽

Brown Rot ◽

Lignocellulosic Waste ◽

Brown Rot Fungi ◽

Hydrolysis Products ◽

Plant Exudates ◽

Rapid Industrialization ◽

Environmentally Friendly Approach

Human endeavors generate a significant quantity of bio-waste, even lignocellulosic waste, due to rapid industrialization and urbanization, and can cause pollution to aquatic ecosystems, and contribute to detrimental animal and human health because of the toxicity of consequent hydrolysis products. This paper contributes to a new understanding of the lignocellulosic waste bio-pretreatment process from a literature review, which can provide better biorefinery operational outcomes. The simultaneous partial biological lignin, cellulose and hemicellulose lysis, i.e., simultaneous semi-lignino-holocellulolysis, is aimed at suggesting that when ligninolysis ensues, holocellulolysis is simultaneously performed for milled lignocellulosic waste instead of having a sequential process of initial ligninolysis and subsequent holocellulolysis as is currently the norm. It is presumed that such a process can be solely performed by digestive enzyme cocktails from the monkey cups of species such as Nepenthes, white and brown rot fungi, and some plant exudates. From the literature review, it was evident that the pretreatment of milled lignocellulosic waste is largely incomplete, and ligninolysis including holocellulolysis ensues simultaneously when the waste is milled. It is further proposed that lignocellulosic waste pretreatment can be facilitated using an environmentally friendly approach solely using biological means. For such a process to be understood and applied on an industrial scale, an interdisciplinary approach using process engineering and microbiology techniques is required.

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Unraveling the natural durability of wood: revealing the impact of decay-influencing characteristics other than fungicidal components

Holzforschung ◽

10.1515/hf-2020-0109 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Liselotte De Ligne ◽

Jan Van den Bulcke ◽

Jan M. Baetens ◽

Bernard De Baets ◽

Gang Wang ◽

...

Keyword(s):

Wood Species ◽

Prunus Avium ◽

Brown Rot ◽

Natural Durability ◽

Anatomical Features ◽

Brown Rot Fungi ◽

Material Characteristics ◽

The One ◽

Block Test ◽

The Impact

AbstractThe effect of fungicidal components in wood has been known for ages, yet there is no method to assess the impact of such components on the durability of a wood species, as compared to other material characteristics that influence decay. In this paper, the importance of fungicidal effects on the natural durability of 10 wood species is assessed in relation to other decay-influencing factors with a new test, the so-called ‘paste test’. By comparing results from this test with the ‘mini-block test’, on both heartwood and leached sapwood, insight is gained into the significance of fungicidal components on the one hand and other material characteristics on the other hand. The durability of species such as Prunus avium was attributed mainly to fungicidal components. For species such as Pterocarpus soyauxii, durability seemed to be an effect of both fungicidal components and moisture-regulating components, while the latter seemed to be of main importance in regulating the decay of Aucoumea klaineana and Entandrophragma cylindricum. Wood-anatomical features, such as the parenchyma content (in case of brown rot fungi) and the vessel-fiber ratio, possibly affect degradation as well. This work shows that fungicidal components are not always of major importance for the durability of a wood species. The authors hereby emphasize the importance of moisture-regulating components and wood anatomy on the durability of wood.

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