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American Society for Testing and Materials

The colonization of land by plants appears to have coincided with the appearance of mycorrhiza-like fungi. Over evolutionary time, fungi have maintained their prominent role in the formation of mycorrhizal associations. In addition, however, they have been able to occupy other terrestrial niches of which the decomposition of recalcitrant organic matter is perhaps the most remarkable. This implies that, in contrast to that of aquatic organic matter decomposition, bacteria have not been able to monopolize decomposition processes in terrestrial ecosystems. The emergence of fungi in terrestrial ecosystems must have had a strong impact on the evolution of terrestrial bacteria. On the one hand, potential decomposition niches, e.g. lignin degradation, have been lost for bacteria, whereas on the other hand the presence of fungi has itself created new bacterial niches. Confrontation between bacteria and fungi is ongoing, and from studying contemporary interactions, we can learn about the impact that fungi presently have, and have had in the past, on the ecology and evolution of terrestrial bacteria. In the first part of this review, the focus is on niche differentiation between soil bacteria and fungi involved in the decomposition of plant-derived organic matter. Bacteria and fungi are seen to compete for simple plant-derived substrates and have developed antagonistic strategies. For more recalcitrant organic substrates, e.g. cellulose and lignin, both competitive and mutualistic strategies appear to have evolved. In the second part of the review, bacterial niches with respect to the utilization of fungal-derived substrates are considered. Here, several lines of development can be recognized, ranging from mutualistic exudate-consuming bacteria that are associated with fungal surfaces to endosymbiotic and mycophagous bacteria. In some cases, there are indications of fungal specific selection in fungus-associated bacteria, and possible mechanisms for such selection are discussed.

Living in a fungal world: impact of fungi on soil bacterial niche development⋆

Methods in Lignin Chemistry

With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much more to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interes...

https://www.fpl.fs.fed.us/documnts/pdf2016/fpl_2016_zhu001.pdf

Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications.

Wood heat treatment has increased significantly in the last few years and is still growing as an industrial process to improve some wood properties. The first studies on heat treatment investigated mainly equilibrium moisture, dimensional stability, durability and mechanical properties. Mass loss, wettability, wood color, and chemical transformations have been subsequently extensively studied, while recent works focus on quality control, modeling, and study the reasons for the improvements. This review explains the recent interest on the heat treatment of wood and synthesizes the major publications on this subject on wood properties, chemical changes, wood uses, and quality control.

https://bioresources.cnr.ncsu.edu/BioRes_04/BioRes_04_1_0370_Esteves_P_Wood_Mod_Heat_Treatment_Rev_367.pdf

Wood modification by heat treatment: a review.

Wood is decomposed by a variety of biological agents, including fungi, bacteria, and insects. Fungi colonize wood and degrade cell wall components to form brown, soft, or white rot. Brown-rot fungi, which degrade primarily the polysaccharide components of wood, leave a lignin framework. White-rot fungi may degrade all cell wall components. The rate and extent of lignin, cellulose, and hemicellulose removal varies among species of white-rot fungi. Soft-rot fungi erode the secondary wall or form discrete cavities within the cell wall. Each type of decay has many forms and can be classified by microscopic and ultrastructural characteristics. Bacteria can attack wood directly to cause various patterns of deterioration such as erosion, cavitation, and tunneling. Bacteria may have a synergistic or antagonistic effect on other microorganisms that inhabit wood. This article reviews the morphological and chemical changes that occur in wood after degradation by different microorganisms and provides information that will help identify the types of deterioration found in wood of historic value.

Biological degradation of wood.

Microbial decay of waterlogged archaeological wood found in Sweden Applicable to archaeology and conservation

Summary White-rot Chemical and microscopic features of wood decay by several ascomycetes in axenic culture are described. The tested ascomycetes caused significant weight losses in birch wood. Daldinia concentrica was especially active, causing a weight loss of 62.9% after 2 months. While lignin and carbohydrates were both degraded, carbohydrates were preferentially attacked. As measured by alkaline nitrobenzene oxidation, syringylpropane units of the lignin were removed selectively. All of the tested ascomycetes eroded fiber cells walls beginning from the lumen. Some also caused cavities in the secondary walls, typical of soft-rot decay. Pine wood was generally resistant to decay; some of those species which were capable of forming soft-rot cavities in birch caused significant weight loss in pine. Alstonia scholaris, a tropical hardwood with a guaiacyl-rich lignin, was resistant to degradation. Soft-rot

Chemistry and Microscopy of Wood Decay by Some Higher Ascomycetes

Soft rot is a form of microbiological wood degradation caused by fungi. The term ‘soft
rot’ was originally proposed by Savory (1954) to be used for ‘decay caused by
cellulose-destroying microfungi to distinguish it from the brown and white rots caused
by wood-destroying basidiomycetes’. The term was based on the observation that wood
surfaces become very soft when attacked by microfungi. Findlay and Savory (1954)
and Savory (1954) described the typical cavity chains within wood cell walls associated
with this form of decay but did not however report any observations of erosion of cell
walls. Such attack was later described by Courtois (1963a,b) and Corbett (1965) for a
number of microfungi that also formed typical cavities. Corbett observed that one
species, Camarosporium ambiens, exclusively eroded the cell walls in birch. Nilsson
(1973) found during an extensive study on wood degradation by microfungi that most
cavity-forming species also eroded the cell walls in birch wood and that several species
exclusively caused an erosion form of attack.

Developments in the Study of Soft Rot and Bacterial Decay

The distribution of lignin peroxidase during degradation of both wood and woody fragments by the white rot fungus Phanerochaete chrysosporium was investigated by using anti-lignin peroxidase in conjunction with postembedding transmission electron microscopy and immuno-gold labeling techniques. The enzyme was localized in the peripheral regions of the fungal cell cytoplasm in association with the cell membrane, fungal cell wall, and extracellular slime materials. In solid wood, lignin peroxidase was detected in low concentrations associated with both superficial and degradation zones within secondary cell walls undergoing fungal attack. A similar but much greater level of extracellular peroxidase activity was associated with wood fragments degraded by the fungus grown under liquid culture conditions optimal for production of the enzyme. Efforts to infiltrate degraded wood pieces with high levels of lignin peroxidase showed the enzyme to be restricted to superficial regions of wood decay and to penetrate wood cell walls only where the wall structure had been modified. In this respect the enzyme was able to penetrate characteristic zones of degradation within the secondary walls of fibers to sites of lignin attack. This suggests a possibility for a close substrate-enzyme association during wood cell wall degradation. Images

Intra- and Extracellular Localization of Lignin Peroxidase during the Degradation of Solid Wood and Wood Fragments by Phanerochaete chrysosporium by Using Transmission Electron Microscopy and Immuno-Gold Labeling.

Thomas Nilsson

Papers

Biological degradation of wood.

Microbial decay of waterlogged archaeological wood found in Sweden Applicable to archaeology and conservation

Chemistry and Microscopy of Wood Decay by Some Higher Ascomycetes

Developments in the Study of Soft Rot and Bacterial Decay

Intra- and Extracellular Localization of Lignin Peroxidase during the Degradation of Solid Wood and Wood Fragments by Phanerochaete chrysosporium by Using Transmission Electron Microscopy and Immuno-Gold Labeling.