Oxalate synthesis was rigorously investigated in a wood-decaying fungus, Gloeophyllum trabeum, using 13C metabolic flux analysis, a method not previously explored in this type of system.
The mechanical properties of phenolic resin reinforced with three different carbon materials were investigated experimentally. The carbon materials: (1) commercially produced carbon nanotubes (CNTs), (2) flash-heated lignocellulose containing CNTs and carbon-black, and (3) cyclically oxidized lignocellulose (Goodell, B. et al. (2008). Journal of Nanoscience and Nanotechnology, 8: 2472-2474) were added to phenolic resin in different weight percentages to fabricate composites. Carbon nanotubes were found to be an effective reinforcing filler increasing tensile strength by 45.34% and Young’s modulus by 19.08% with a 2% loading. The flash-heated material increased Young’s modulus by 11.04% with a 2% loading but did not affect tensile strength. The cyclically heated material did not contain CNTs, their inclusion in the composites reduced Young’s modulus and, for the 1% loading, reduced tensile strength as well.
In forest ecosystems, fungi and bacteria are key actors in wood degradation. However, few studies have focused on the impact of introducing decayed wood into forest environments to gauge successional colonization by natural bacterial and fungal communities following partial decay. Coniferous forests are dominated by brown rot fungi that are involved in the earliest phase of lignocellulose breakdown, which therefore influences colonization by other microorganisms. This study aimed to investigate the bacterial and fungal colonization of degraded Norway spruce ( Picea abies ) after intermediate and advanced laboratory-based pre-degradation by the brown rot fungus Gloeophyllum trabeum . Using Illumina metabarcoding, the in situ colonization of the wood blocks was monitored after 70 days after the blocks were placed on the forest floor and covered with litter. We observed significant changes in the bacterial and fungal communities associated with the pre-degradation stage, with the wood substrate condition acting as a gatekeeper by reducing richness for both microbial communities and diversity of fungal communities. Our data also suggested that fungal and bacterial communities can be involved in both synergistic and antagonistic processes during wood decomposition.
Wood decay by fungi is typically classified into three types: soft rot, brown rot and white rot. Brown rot fungi are the most prevalent with regard to attack on coniferous, structural wood products in North America. The wood decayed by brown rot fungi is typically brown and crumbly and it is degraded via both non-enzymatic and enzymatic systems. A series of celluloytic enzymes are employed in the degradation process by brown rot fungi, but no lignin degrading enzymes are typically involved. White rot fungi are typically associated with hardwood decay and their wood decay patterns can take on different forms. White rotted wood normally has a bleached appearance and this may either occur uniformly, leaving the wood a spongy or stringy mass, or it may appear as a selective decay or a pocket rot. White rot fungi possess both cellulolytic and lignin degrading enzymes and these fungi therefore have the potential to degrade the entirety of the wood structure under the correct environmental conditions. Soft rot fungi typically attack higher moisture, and lower lignin content wood and can create unique cavities in the wood cell wall. Less is known about the soft rot degradative enzyme systems, but their degradative mechanisms are reviewed along with the degradative enzymatic and non-enzymatic systems known to exist in the brown rot and white rot fungi. As we learn more about the non-enzymatic systems involved in both brown and white rot degradative systems, it changes our perspective on the role of enzymes in the decay process. This in turn is affecting the way we think about controlling decay in wood preservation and wood protection schemes, as well as how we may apply fungal decay mechanisms in bioindustrial processes.
Molecular techniques are now routinely used in the identification, detection and analysis of wood degrading organisms. An overview of some of the early work on nucleic acid isolation and characterization will be followed by a discussion of the power of sequencing and other procedures for better understanding: the mechanisms involved in the biological degradation of wood, the metabolic basis of preservative function and ultimately the evolutionary history and ecological function of some of these unique organisms.
Abstract Effects of the heating rate on the physical properties of carbonized wood were investigated by comparing the dimensional shrinkage, electrical resistivity, Young's modulus, and the evolution of turbostratic crystallites in maple hardwood samples carbonized at 600°C, 800°C, and 1000°C under heating regimes of 3°C h -1 and 60°C h -1 . Important carbonized wood properties that developed at high temperature and high heating rates could also be produced at slow heating rates and lower temperatures. Furthermore, slow heating rates promoted the formation and growth of graphene sheets in turbostratic crystallites, which had a significant influence on the electrical resistivity and Young's modulus of the carbonized wood. The results indicate that the graphene sheets of turbostratic crystallites formed during wood carbonization were arranged parallel to the axial direction of wood cells and at an angle to the circumference of wood cells in the cross-sectional plane. With regard to the production of carbon products, a decrease in the heating rate may be beneficial for char properties and the prevention of crack production during manufacture of large monolithic carbon specimens from wood and wood-based materials.
