One strategy for improving the treatability of refractory wood species is biological incising, and
its efficiency depends on how the microorganisms modify the porous structure of the wood. Evaluation ...of the bioincised wood treatability on a micro-scale can thus help to better understand the treatability enhancing mechanisms. In the present study, the biodegradation pattern and micro-scale treatability of Loblolly pine (Pinus taeda L.) heartwood were determined after bioincising with the white-rot fungus Physisporinus vitreus (Pers.: Fr.) P. Karsten isolate 136 and bacterium Bacillus subtilis UTB22. Oven-dried specimens with dimensions of 50 mm × 25 mm × 15 mm (L × T × R) were incubated with the microorganisms at (23±2) °C and (65±5) % relative humidity for six weeks. The control and exposed wood blocks were then pressure treated by 1 % fluorescent dye (fluorescein)-containing water to study the treatability pattern under a fluorescence microscope. The longitudinal and tangential air permeability and compression strength parallel to the grain of the specimens were also determined at the end of the incubation period. Scanning electron microscopic (SEM) studies showed that degradation by B. subtilis UTB22 was limited to the pit membranes, but the cell walls were also degraded to some extent by P. vitreus. The fungus caused a higher mass loss compared to the bacterium, whereas the permeability enhancing ability of the bacterium was more pronounced. The fluorescent dye tracer also showed that higher treatability with more uniformity was obtained by B. subtilis UTB22. The improvement in treatability by both microorganisms was mainly due to the degradation of the earlywood tracheids.
Jedna od metoda poboljšanog impregniranja slabo poroznih vrsta drva jest tretiranje drva mikroorganizmima, a cilj tog postupka jest promjena porozne strukture drva. Evaluacija tretmana drva mikroorganizmima može pridonijeti boljem razumijevanju mehanizama poboljšanja prodora zaštitnog sredstva u drvo. U ovom je istraživanju promatrana biorazgradnja i impregnacija srži lobodijskog bora (Pinus taeda L.) na mikrorazini nakon izloženosti drva gljivi bijele truleži Physisporinus vitreus (Pers.: Fr.) P. Karsten izolat 136 i bakteriji Bacillus subtilis UTB22. Apsolutno suhi uzorci drva dimenzija 50 mm × 25 mm × 15 mm (L × T × R) zaraženi su mikroorganizmima pri 23±2 °C i 65±5 % relativne vlažnosti zraka tijekom šest tjedana. Nakon toga kontrolni i zaraženi blokovi drva tlačnim su postupkom impregnirani fluorescentnim bojilom otopljenim u vodi (1 %-tni fluorescein) kako bi se pod fluorescentnim mikroskopom promotrio učinak tretmana drva mikroorganizmima. Na kraju inkubacije utvrđena je propusnost zraka u uzdužnom i tangentnom smjeru te izmjerena čvrstoća na tlak paralelno s vlakancima. Istraživanje pretražnim elektronskim mikroskopom (SEM) pokazalo je da je razgradnja bakterijom B. subtilis UTB22 ograničena na membrane jažica, dok su stanične stijenke u određenoj mjeri razgrađene djelovanjem gljive P. vitreus. Gljiva je uzrokovala opsežniji gubitak mase nego bakterija, dok je sposobnost bakterije da poveća propusnost bila veća. Fluorescentno bojilo također je pokazalo da je bakterijom B. subtilis UTB22 postignuta bolja propusnost, s većom ujednačenošću. Poboljšanje propusnosti primjenom obaju mikroorganizama uglavnom je posljedica razgradnje traheida ranog drva.
Eight undescribed lanostane triterpenoids, physivitrins A–H, along with four known analogues, were isolated from cultures of the fungus Physisporinus vitreus. Their structures were elucidated on the ...basis of extensive spectroscopic methods, in which the absolute configuration of physivitrin A was elucidated using electronic circular dichroism calculation and nuclear magnetic resonance (NMR) calculation with DP4+ analysis. Physivitrins B and C showed inhibitory activities against nitric oxide (NO) production in LPS-activated RAW264.7 macrophages with IC50 values of 7.5 and 23.5 μM, respectively. Meanwhile, proinflammatory cytokines (TNF-α, iNOS and IL-1β) mRNA expression was also inhibited by physivitrin B significantly.
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•Eight undescribed triterpenoids were isolated from Physisporinus vitreu.•Two compounds exhibited inhibitory activities against nitric oxide production.•One inhibited three proinflammatory cytokines mRNA expression.
Laccases are versatile biocatalysts that are prominent for industrial purposes due to their extensive substrate specificity. Therefore, this research investigated producing laccase from
Physisporinus ...vitreus
via liquid fermentation. The results revealed that veratryl alcohol (4mM) was the most effective inducer 7500U/L. On the other hand, Zn ions inhibited laccase production. The optimum carbon and nitrogen sources were glucose and tryptone by 5200 and 3300 U/L, respectively. Moreover, solvents exhibited various impacts on the enzyme activity at three different solvent concentrations (5%, 10% and 20%), however, it showed a highest activity at 5% of the investigated solvent. Ferric ions inhibited the enzyme activity. In addition, the enzyme has a high ability to decolorize azo dyes when using syringaldehyde as a mediator. The purified laccase from
Physisporinus vitreus
is a promising substance to be used for industrial and environmental applications due to its stability under harsh conditions and efficiency in decolorization of dyes.
Graphical abstract
Bioincising is a biotechnological process to improve the permeability of wood by biological organisms. In recent years, there has been a great interest to determine the changes in the anatomical ...structure of wood as a result of bioincising process. In this study, the effects of bioincising by Physisporinus vitreus on the pit structure and permeability of Picea orientalis L. sapwood and heartwood were studied. Bioincised and non-bioincised samples were then treated with micronized copper quaternary and Celcure AC-500 wood preservatives by either dipping or vacuum method. The copper distribution and amount of copper retained in treated wood were evaluated by SEM-EDX and ICP-OES, respectively. The area of copper fixation in treated wood was also measured by the ArcGIS software package. The effects of P. vitreus activity were examined in the wood microstructure after bioincising by light microscope and SEM analyses on radial sections. After the bioincising, a significant increase was observed in the uptake of wood preservatives by vacuum, particularly in heartwood. The measurements on bordered pit, crossfield pit, and ray tracheid bordered pit dimensions in the microstructure of wood indicated that the degradation of pits was the most important factor in improved penetration and uptake of preservative solutions employed.
The fungus Physisporinus vitreus and the bacterium Bacillus subtilis are commonly used organisms in wood biotechnology to increase wood permeability. However, comparative researches on wood ...destruction by these biological wood decomposers are scarce, particularly from microscopic and chemical perspectives. This study aimed to compare the fungal and bacterial wood destruction patterns over time. Loblolly pine (Pinus taeda L.) heartwood samples were exposed to both organisms for six and nine weeks; microscopic and spectroscopic analyses of the incubated wood were performed, and mass loss of samples was calculated. Both organisms initially destroyed the pit tori and ray parenchyma cells, but B. subtilis was more selective in its consumption of wood components. It exclusively consumed hemicelluloses and free carbohydrates in wood, whereas the fungus destroyed all chemical components simultaneously. The digestion of bordered pits by B. subtilis was more selective than that by P. vitreus, making it a better choice for controlled wood destruction. By extending the exposure duration, the bacterial destruction pattern remained consistent, whereas fungal destruction spread to the secondary wall of the tracheids. Understanding the interactions between microbes and wood can lead to a more effective and efficient use of this natural resource.
Even though oriental spruce (Picea orientalis L.), a common species in the East Black Sea Region of Turkey, is used in a wide range of applications, its wood has low permeability. This study ...investigated the degradation effects of the bioincising process to improve its treatability with wood preservatives on the microstructure of oriental spruce wood. Test samples were previously subjected to bioincising by Physisporinus vitreus fungus, and the bioincised samples were examined under both a light microscope and scanning electron microscope to observe the effects of the bioincising on the anatomical properties. Bordered pits on the longitudinal tracheid radial walls, piceoid-type cross-field pits, ray tracheid bordered pits, and ray tracheid cell walls in the earlywood and latewood regions within a growth ring were particularly subjected to anatomical evaluations. In the study, the degradation intensity in the samples after the bioincising was well correlated with the weight losses occurred. Splits and factures were determined on the tori of bordered pits on the tracheid cell walls while tears and cracks were present on the pit apertures. The results also show that P. vitreus, a Type I and II white rot fungus, may cause a Type I soft rot.
Versatile peroxidases (VPs) have outstanding oxidative capacity for a wide range of substrates and potential applications in industrial sectors and more. In this study, the VP1 from Physisporinus ...vitreus PF18 was obtained and overexpressed as inclusion body in Escherichia coli, then refolded successfully in vitro. Steady-state kinetic analysis and dye decolorization indicated that Mn(II) could promote the oxidation of low redox potential substrates and increase decolorization efficiency up to 70% by recombinant VP1 (rVP1). Results of pyrolysis-gas chromatography mass spectroscopy showed that most derivatives of G-type lignin increased slightly by rVP1 treatment, compared with the control. Surprisingly, the ratio of guaiacyl-type to syringyl-type derivatives (G/S) after rVP1 treatment was 5.4 times higher than that of the control. The polymerization of alkali lignin may be attributed to the transformation of S-type into G-type lignin by demethoxylation. Thus, our study provides a high-efficient candidate for biodegradation and biocatalysis.
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•We first expressed a versatile peroxidase (rVP1) from Physisporinus vitreus in Escherichia coli with good yield.•Recombinant rVP1 had complete oxidative capacity on both high and low redox potential substrates.•rVP1 manganese-dependent activity activated by Mn2+ to promote dye decolorization significantly.•rVP1 modified alkali lignin through demethoxylation and change G/S ratio.
Bioincising impacts of white-rot fungus, Physisporinus vitreus and soft-rot fungus, Xylaria longipes on the porous structure and radial permeability of poplar normal wood and tension wood were ...studied. Fungal cultivation was performed in an incubator at 25 °C and 85% relative humidity for 15, 30 and 45 days. Fracture of pectin-rich gelatinous layer of tension wood occurred due to incubation with P. vitreus. However, a simultaneous degradation in the cell walls and middle lamellae was observed. Both fungi had negative effects on the permeability, probably due to blocking of fluid flow paths by the fungal hyphae. Reduction in the permeability was more remarkable with P. vitreus. Our results showed that the role of G-layer containing fibers can be neglected for radial permeability of tension wood. Overall, such fungal bioincising techniques cannot be considered as successful approaches to improve the permeability of tension wood.
•Bioincising impacts of Physisporinus vitreus and Xylaria longipes on the porous structure and permeability of poplar normal and tension wood was examined.•P. vitreus and X. longipes had a negative effect on the wood permeability, probably due to blocking the fluid flow paths by the fungi hyphae.•Radial permeability of poplar tension wood cannot be controlled by G-layer.
In this study, changes in the hygroscopic properties of two main wood species for violin making, Norway spruce and sycamore, after treatment with
and
were investigated. Swelling and moisture sorption ...capacity of wood at the growth ring scale were visually and quantitatively assessed by thermal neutron radiography analysis. It was demonstrated that the fungal treatment improved the dimensional stability of both Norway spruce and sycamore, but also increased their moisture adsorption capacity. Dynamic vapor sorption tests and measurements of the changes in dimensions of the specimens in the laboratory were in good agreement with the results of neutron radiography analysis. The main difference between the moisture sorption of the untreated controls and treated wood was observed at high relative humidity, e.g., above 75%. The contradictory behavior of the increased hygroscopicity and reduced swelling was explained by selective degradation of the chemical components and condensation of the moisture content gained in the capillary voids that developed in the cell walls during fungal decay.
The credo of every scientist working in the field of applied science is to transfer knowledge “from science to market,” a process that combines (1) science (fundamental discoveries and basic ...research) with (2) technology development (performance assessment and optimization) and (3) technology transfer (industrial application). Over the past 7 years, we have intensively investigated the potential of the white rot fungus,
Physisporinus vitreus
, for engineering value-added wood products. Because of its exceptional wood degradation pattern, i.e., selective lignification without significant wood strength losses and a preferential degradation of bordered pit membranes, it is possible to use this fungus under controlled conditions to improve the acoustic properties of tonewood (i.e., “mycowood”) as well as to enhance the uptake of preservatives and wood modification substances in refractory wood species (e.g., Norway spruce), a process known as “bioincising.” This minireview summarizes the research that we have performed with
P. vitreus
and critically discusses the challenges encountered during the development of two distinct processes for engineering value-added wood products. Finally, we peep into the future potential of the bioincising and mycowood processes for additional applications in the forest and wood industry.
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