Degradation of the lignocellulose complex in wood

1995 ◽  
Vol 73 (S1) ◽  
pp. 999-1010 ◽  
Author(s):  
Robert A. Blanchette

Degradation of the lignocellulose complex in wood varies depending on the microorganism causing decay. The degradative processes of white-, brown-, and soft-rot fungi as well as different forms of bacterial degradation are presented. Ultrastructural methods were used to elucidate cell-wall alterations that occurred during the various stages of decay. In wood inoculated with the white-rot fungus Ceriporiopsis subvermispora, changes in the cell wall, such as electron-dense zones after staining with uranyl acetate, were evident during incipient stages of decay. The ratio of syringyl:guaiacyl lignin of different woods, different cell types, and even the different layers within a cell wall influenced the type and extent of decay by white-rot fungi. Soft rots caused unique changes in the lignocellulose matrix. The type of wood substrate governed the form (type I or type II) of soft rot that occurred. Brown-rot fungi depolymerized cellulose early in the decay process and degraded cellulose without prior removal of lignin. Bacterial degradation was common in waterlogged woods and three forms, tunneling, erosion and cavitation, are discussed. In addition to an improved understanding of decay processes in living trees and forest products, knowledge of decomposition mechanisms is important to utilize effectively these microorganisms for new industrial bioprocessing technologies. Key words: biodegradation, white rot, brown rot, soft rot, bacterial degradation.

2010 ◽  
Vol 36 (2) ◽  
pp. 81-85
Author(s):  
Kahoru Matsumoto ◽  
Futoshi Ishiguri ◽  
Kazuya Iizuka ◽  
Shinso Yokota ◽  
Naoto Habu ◽  
...  

To obtain the basic information needed to estimate the degree of decay from compressive strength measured using a Fractometer (CS), relationships between CS and the contents of chemical components were analyzed for Magnolia wood decayed by three types fungi (brown rot, white rot, and soft rot fungi) at various decay levels. Weight loss ratio was significantly, negatively correlated with CS in woods decayed by brown rot and white rot fungi. In addition, a relatively high correlation coefficient was recognized between CS and holocellulose or α-cellulose content, except for wood decayed by soft rot fungus. The results obtained showed that Fractometer can detect the decrease of CS at relatively early stage of decay.


Holzforschung ◽  
2013 ◽  
Vol 67 (7) ◽  
pp. 825-832 ◽  
Author(s):  
Anna-Kaisa Anttila ◽  
Anna Maria Pirttilä ◽  
Hely Häggman ◽  
Anni Harju ◽  
Martti Venäläinen ◽  
...  

Abstract In the last decades, many wood preservatives have been prohibited for their ecotoxicity. The present article is focusing on the conifer-derived condensed tannins as environment-friendly options for the substitution of artificial wood preservatives. Eight different tannin fractions were extracted from spruce cones, spruce barks, and pine cones. The parameters of tannin extraction, such as the methods of purification and concentration of active components in the extracts, have been investigated. The cone and bark extracts were tested for the growth inhibition of eight brown-rot fungi, three white-rot fungi, and four soft-rot fungi in liquid cultures. The cone tannins provided a more efficient fungal growth inhibition than bark tannins. Purification increased the antifungal properties of the extracts. The growth of brown-rot fungi was inhibited by the tannins already at low concentrations. However, the extracts were not effective against the white-rot or soft-rot fungi. More investigation is needed concerning the tannin source and the purification procedure of the extracts before tannins can be considered as an ecologically benign wood preservative.


2020 ◽  
Vol 8 (12) ◽  
pp. 1931
Author(s):  
Ehsan Bari ◽  
Geoffrey Daniel ◽  
Nural Yilgor ◽  
Jong Sik Kim ◽  
Mohammad Ali Tajick-Ghanbary ◽  
...  

Fungal wood decay strategies are influenced by several factors, such as wood species, moisture content, and temperature. This study aims to evaluate wood degradation characteristics of spruce, beech, and oak after exposure to the white-rot fungi Pleurotusostreatus and Trametesversicolor. Both fungi caused high mass losses in beech wood, while spruce and oak wood were more resistant to decay. The moisture content values of the decayed wood correlated with the mass losses for all three wood species and incubation periods. Combined microscopic and chemical studies indicated that the two fungi differed in their decay behavior. While T. versicolor produced a decay pattern (cell wall erosion) typical of white-rot fungi in all wood species, P. ostreatus caused cell wall erosion in spruce and beech and soft-rot type I (cavity formation) decay in oak wood. These observations suggest that P. ostreatus may have the capacity to produce a wider range of enzymes/radicals triggered by the chemical composition of wood cell walls and/or local compositional variability within the cell wall.


Holzforschung ◽  
2008 ◽  
Vol 62 (6) ◽  
Author(s):  
Jonathan S. Schilling ◽  
Kaitlyn M. Bissonnette

AbstractWood-degrading fungi commonly grow in contact with calcium (Ca)-containing building materials and may import Ca and iron (Fe) from soil into forest woody debris. For brown rot fungi, imported Ca2+may neutralize oxalate, while Fe3+may facilitate Fenton-based degradation mechanisms. We previously demonstrated, in two independent trials, that degradation of spruce by wood-degrading fungi was not promoted when Ca or Fe were imported from gypsum or metallic Fe, respectively. Here, we tested pine wood with lower endogenous Ca than the spruce blocks used in prior experiments, and included a pure gypsum treatment and one amended with 1% with FeSO4. Electron microscopy with microanalysis verified that brown rot fungiSerpula himantioidesandGloeophyllum trabeumand the white rot fungusIrpex lacteusgrew on gypsum and produced iron-free Ca-oxalate crystals away from the gypsum surface. Wood cation analysis verified significant Fe import by both brown rot isolates in Fe-containing treatments. Wood degradation was highest in Fe-gypsum-containing treatments for all three fungi, although only wood degraded byI. lacteushad significant Ca import. We suggest that Fe impurities may not exacerbate brown rot, and that both brown and white rot fungi may utilize Ca-containing materials.


Author(s):  
Aydan Atalar ◽  
Nurcan Çetinkaya

The efforts to break down the lignocellulosic complex found in the cell wall of straws, besides digestible cellulose and hemicellulose by rumen fermentation, improvement of straw digestibility by the degradation of indigestible lignin fraction of complex by using of biotechnological methods is one of the focus areas of animal nutritionists in recent years. Biological method sare prefer redover other methods due to the environmental friendliness. In the biological treatment methods of lignocellulosic complex, biodiversity of bacteria, enzymes and fungi gives opportunity to select lignin degrading species. Mycobacterium, Arthrobacter and Flavobacterium genre bacteria are used to degrade lignin by bacterial treatment. Lignocellulolytic enzymes isolated from different varieties of fungi are used in enzyme treatment. There are 3 genres of fungus that are white, Brown and soft rot in fungal treatments. Brown rot fungi prefer ably attack cellulose and hemicelluloses, but not lignin. White rot fungi attack the lignin and break up lignol bonds and aromatic ring. White rot fungi break down polysaccharides with hydrolytic enzymes such as cellulase, xylanase, and lignin with oxidative ligninolytic enzymes such as lignin peroxidase and laccase. Because of the fact that the microorganisms that can break down the lignocellulosic materials are the fungi and the cost is low, the application of white rot fungi is possible. In this paper, improvement the lignocellulosic comlex digestibility of straw by biological treatment with the advantage of biodiversity is discussed.


Author(s):  
Aydan Atalar ◽  
Nurcan Çetinkaya

The efforts to break down the lignocellulosic complex found in the cell wall of straws, besides digestible cellulose and hemicellulose by rumen fermentation, improvement of straw digestibility by the degradation of indigestible lignin fraction of complex by using of biotechnological methods is one of the focus areas of animal nutritionists in recent years. Biological method sare prefer redover other methods due to the environmental friendliness. In the biological treatment methods of lignocellulosic complex, biodiversity of bacteria, enzymes and fungi gives opportunity to select lignin degrading species. Mycobacterium, Arthrobacter and Flavobacterium genre bacteria are used to degrade lignin by bacterial treatment. Lignocellulolytic enzymes isolated from different varieties of fungi are used in enzyme treatment. There are 3 genres of fungus that are white, Brown and soft rot in fungal treatments. Brown rot fungi prefer ably attack cellulose and hemicelluloses, but not lignin. White rot fungi attack the lignin and break up lignol bonds and aromatic ring. White rot fungi break down polysaccharides with hydrolytic enzymes such as cellulase, xylanase, and lignin with oxidative ligninolytic enzymes such as lignin peroxidase and laccase. Because of the fact that the microorganisms that can break down the lignocellulosic materials are the fungi and the cost is low, the application of white rot fungi is possible. In this paper, improvement the lignocellulosic comlex digestibility of straw by biological treatment with the advantage of biodiversity is discussed.


Holzforschung ◽  
2011 ◽  
Vol 65 (6) ◽  
pp. 883-888 ◽  
Author(s):  
Olaf Schmidt ◽  
Dong Sheng Wei ◽  
Walter Liese ◽  
Elisabeth Wollenberg

Abstract The degradation of several Asian bamboo species by white-, brown-, and soft-rot fungi was investigated under laboratory conditions by means of different test methods. Severe deterioration was caused by all three fungi types. The bamboo species differed in durability. Samples from 6 months young culms decayed more than older ones. There were no significant differences between 1- and 3-year-old culms. Samples taken from the culm top were more vulnerable to decay than those from the bottom. Wet bamboo samples with soil contact were especially degraded by the white-rot fungus Schizophyllum commune, whereas the brown-rot fungus Coniophora puteana produced the greatest mass loss in drier samples. The sealing of bamboo crosscut ends reduced the rate of decay.


2021 ◽  
Vol 9 (1) ◽  
pp. 149
Author(s):  
Neha Sahu ◽  
Zsolt Merényi ◽  
Balázs Bálint ◽  
Brigitta Kiss ◽  
György Sipos ◽  
...  

Wood-decaying Basidiomycetes are among the most efficient degraders of plant cell walls, making them key players in forest ecosystems, global carbon cycle, and in bio-based industries. Recent insights from -omics data revealed a high functional diversity of wood-decay strategies, especially among the traditional white-rot and brown-rot dichotomy. We examined the mechanistic bases of wood-decay in the conifer-specialists Armillaria ostoyae and Armillaria cepistipes using transcriptomic and proteomic approaches. Armillaria spp. (Fungi, Basidiomycota) include devastating pathogens of temperate forests and saprotrophs that decay wood. They have been discussed as white-rot species, though their response to wood deviates from typical white-rotters. While we observed an upregulation of a diverse suite of plant cell wall degrading enzymes, unlike white-rotters, they possess and express an atypical wood-decay repertoire in which pectinases and expansins are enriched, whereas lignin-decaying enzymes (LDEs) are generally downregulated. This combination of wood decay genes resembles the soft-rot of Ascomycota and appears widespread among Basidiomycota that produce a superficial white rot-like decay. These observations are consistent with ancestral soft-rot decay machinery conserved across asco- and Basidiomycota, a gain of efficient lignin-degrading ability in white-rot fungi and repeated, complete, or partial losses of LDE encoding gene repertoires in brown- and secondarily soft-rot fungi.


Holzforschung ◽  
2012 ◽  
Vol 66 (2) ◽  
Author(s):  
Zefang Xiao ◽  
Yanjun Xie ◽  
Carsten Mai

Abstract Scots pine sapwood (Pinus sylvestris L.) and European beech wood (Fagus sylvatica L.) were treated with glutaraldehyde (GA) in aqueous solution in the presence of magnesium chloride as a catalyst to evaluate the durability improvement towards staining and rot fungi. The GA modified specimens were dipped in a spore suspension of the blue stain fungus Aureobasidium pullulans and incubated for 8 weeks. The growth on both pine and beech wood was restrained, when the weight percent gain (WPG) of the specimens was above 7%. Under this condition, GA-modified beech wood did not suffer any mass loss after incubation with the white rot fungus Trametes versicolor. The threshold to prevent decay of beech and pine specimens towards the brown rot fungus Coniophora puteana was at a WPG of only 3%. GA treatment to a WPG over 6% protected the Scots pine stakes from soft rot decay during 32 weeks’ exposure according to ENv 807 (2001).


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Caihong Weng ◽  
Xiaowei Peng ◽  
Yejun Han

AbstractLignin, the most abundant renewable aromatic compound in nature, is an excellent feedstock for value-added bioproducts manufacturing; while the intrinsic heterogeneity and recalcitrance of which hindered the efficient lignin biorefinery and utilization. Compared with chemical processing, bioprocessing with microbial and enzymatic catalysis is a clean and efficient method for lignin depolymerization and conversion. Generally, lignin bioprocessing involves lignin decomposition to lignin-based aromatics via extracellular microbial enzymes and further converted to value-added bioproducts through microbial metabolism. In the review, the most recent advances in degradation and conversion of lignin to value-added bioproducts catalyzed by microbes and enzymes were summarized. The lignin-degrading microorganisms of white-rot fungi, brown-rot fungi, soft-rot fungi, and bacteria under aerobic and anaerobic conditions were comparatively analyzed. The catalytic metabolism of the microbial lignin-degrading enzymes of laccase, lignin peroxidase, manganese peroxidase, biphenyl bond cleavage enzyme, versatile peroxidase, and β-etherize was discussed. The microbial metabolic process of H-lignin, G-lignin, S-lignin based derivatives, protocatechuic acid, and catechol was reviewed. Lignin was depolymerized to lignin-derived aromatic compounds by the secreted enzymes of fungi and bacteria, and the aromatics were converted to value-added compounds through microbial catalysis and metabolic engineering. The review also proposes new insights for future work to overcome the recalcitrance of lignin and convert it to value-added bioproducts by microbial and enzymatic catalysis.


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