| 1. |
- Daniel, Geoffrey, et al.
(author)
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Comparison of the decay behavior of two white‐rot fungi in relation to wood type and exposure conditions
- 2020
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In: Microorganisms. - : MDPI AG. - 2076-2607. ; 8
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Journal article (peer-reviewed)abstract
- 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 ofspruce, beech, and oak after exposure to the white-rot fungi Pleurotus ostreatus and Trametes versicolor.Both fungi caused high mass losses in beech wood, while spruce and oak wood were more resistant todecay. The moisture content values of the decayed wood correlated with the mass losses for all threewood species and incubation periods. Combined microscopic and chemical studies indicated that thetwo fungi di ered in their decay behavior. While T. versicolor produced a decay pattern (cell wallerosion) typical of white-rot fungi in all wood species, P. ostreatus caused cell wall erosion in spruceand beech and soft-rot type I (cavity formation) decay in oak wood. These observations suggest thatP. ostreatus may have the capacity to produce a wider range of enzymes/radicals triggered by thechemical composition of wood cell walls and/or local compositional variability within the cell wall.
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| 2. |
- Daniel, Geoffrey, et al.
(author)
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Method for characterizing extracellular proteins from the cell wall proteome of the copper tolerant fungus Phialophora malorum
- 2019
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In: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 144
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Journal article (peer-reviewed)abstract
- Phialophora malorum is a well-known copper tolerant fungus causing soft rot decay of copper-treated wood in-service in ground contact situations worldwide. The aim of the present work was to develop a method that allowed studies of the mechanism(s) behind extracellular copper tolerance by examining the profile of proteins expressed by P. malorum in the cell wall/slime (subproteome) environment in mycelia grown in Cu-supplemented media. The study involves development of a novel non-destructive approach using mild extraction, concentration, separation (SDS-PAGE electrophoresis) and characterization (MALDI-TOF MS/MS) of the proteins present. Studies revealed differential protein profiles and expression in Cu-supplemented (0.1% CuSO4) vs control shake cultures after 10 days growth. Twelve proteins including several hydrolytic (i.e. glucosidases, pectinase, polygalacturonase) enzymes were either unique or over-expressed in Cu-cultures compared to controls. The cell wall location of the proteins was consistent with a role in copper tolerance and detoxification by binding Cu-ions extracellularly. Several of the proteins (e.g. hydrolases, pectinase) are also involved in wood cell wall biomineralization. It is proposed that the concentration of metabolites (organic acids) slowly released in close vicinity of hyphal surfaces by weakly bound enzymes over-expressed through Cu-stress may function to reduce levels of free non-chelated Cu (II) ions entering the cell cytoplasm and therefore provide a first level of defense against copper toxicity.
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| 5. |
- Gao, Jie, et al.
(author)
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Chemical and ultrastructural changes in compound middle lamella (CML) regions of softwoods thermally modified by the Termovuoto process
- 2014
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In: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 68, s. 849-859
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Journal article (peer-reviewed)abstract
- Silver fir and Norway spruce wood have been thermally modified (TMW) for 3-4 h at 160 degrees C, 180 degrees C, 200 degrees C, and 220 degrees C by means of the thermovacuum process (Termovuoto), and the ultrastructural and chemical changes in the compound middle lamella (CML), including the middle lamella cell corner (MLcc) regions (CMLcc), were investigated. Severe anatomical and histochemical changes were prominent above treatment temperatures of 200 degrees C; thus, woods treated at 220 degrees C for 4 h were in focus. Immunocytochemical studies showed that noncellulosic polysaccharides, such as pectin, xyloglucan, xylan, and mannan, were significantly degraded in CMLcc regions of TMWs. After treatment, the CMLcc regions were composed almost entirely of modified lignin with increased amounts of acidic groups. With cytochemical staining for lignin, many electron dense particulates were detected in the CMLcc regions of TMWs, indicating early degradation/alteration by the Termovuoto treatment.
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| 6. |
- Gao, Jie, et al.
(author)
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Decay resistance of softwoods and hardwoods thermally modified by the Thermovouto type thermo-vacuum process to brown rot and white rot fungi
- 2016
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In: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 877-884
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Journal article (peer-reviewed)abstract
- Softwoods (SW, spruce and fir) and hardwoods (HW, ash and beech) were thermally modified by the thermo-vacuum (Termovuoto) process for 3-4 h in the temperature range 160-220 degrees C (TMW160-220 degrees C) and their fungal durability were examined in soil-block tests with two brown rot (BR, Postia placenta, Gloeophyllum trabeum) and two white rot (WR, Pycnoporus sanguineus, Phlebia radiata) fungi. SW-TMW160-220 degrees C were exposed to P. placenta and P. sanguineus and HW-TMW190-220 degrees C to all fungal species. Considerable improvement (durability class 1-3) in decay resistance was only achieved for SW-and HW-TMW 220 degrees C. Thermal modification (TM) below 200 degrees C influenced decay resistance negatively in case of some fungal species applied for both SW and HW. Judged by the durability class, decay resistance was higher in HW- than in SW-TMW at high TM temperature. Behavior of TM differed significantly between ash (ring-porous HW) and beech (diffuse-porous HW). A comparison between results of soil-and agar-block tests on Termovouoto wood demonstrated that the influence of testing method in terms of assignment to durability classes is not significant.
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| 7. |
- Gao, Jie, et al.
(author)
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Effect of thermal modification on the durability and decay patterns of hardwoods and softwoods exposed to soft rot fungi
- 2018
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In: International Biodeterioration and Biodegradation. - : Elsevier BV. - 0964-8305. ; 127, s. 35-45
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Journal article (peer-reviewed)abstract
- The durability and decay patterns of thereto-vacuum (Terrnowoto process for 3-4 h at 160-220 degrees C) treated hardwoods (ash, beech) and softwoods (spruce, fir) TMWs exposed to three soft rot fungi (Chaetorniwn globoswn, Phialophom malorum, P. mutabilis) were investigated using the soil-block test, light- and electron microscopy. Monitoring of mass loss over 1 year indicated that soft rot fungi do not attack softwood TMWs as rapidly or as extensively as hardwood TMWs. Decay resistance progressively increased in hardwood TMWs with increase in temperature but was unclear/or varied in softwood TMWs depending on fungal/wood species, particularly at lower temperatures (160-180 degrees C). Soft- and hardwood TMWs showed a major increase in decay resistance at 200-220 degrees C and 210-220 degrees C, respectively. Light microscopy of decayed hardwood TMWs showed formation of typical soft rot Type-I cavities in fibres at lower temperatures (190-200 degrees C). However, cavities were significantly inhibited or delayed at higher temperatures (210-220 degrees C). Cavity formation in vessels and parenchyma cells were only observed in beech TMW treated at 190 degrees C or references, indicating higher resistance than fibres. Transmission electron microscopy of decayed ash TMW treated at 200 degrees C showed a radial-like distribution of electron dense materials in cavities and lack of fibrillar-like materials within degraded fibre walls, which differed from reference.
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| 8. |
- Gao, Jie, et al.
(author)
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Effect of thermal modification on the micromorphology of decay of hardwoods and softwoods by the white rot fungus Pycnoporus sanguineus
- 2018
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In: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 72, s. 797-811
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Journal article (peer-reviewed)abstract
- Thermal modification (TM) of wood at high temperatures can lead to significantly improved decay resistance against white rot (WR) fungi, but little is known about the mechanism of this improvement at the cellular level. As a contribution to this topic, hardwoods (HWs) (ash, beech) and softwoods (SWs) (spruce, fir) were submitted to the Termovuoto (R) TM process at 220 degrees C for 3-4 h (shortly TMW220 degrees c) and were degraded by the WR fungus Pycnoporus sanguineus. The results were studied using microscopy techniques. Decay occurred preferentially via cell wall delignification prior to the removal of cellulose and hemicelluloses. Concerning this effect and fungal colonization, there were no essential differences between TMW220 degrees c and the unmodified reference of all wood species. TMW220 degrees c, however, showed a number of characteristic changes in decay morphology. Narrow and distinct concentric transition zones were observable in decayed fiber and tracheid cell walls, which demark the lignified and delignified regions. Moreover, cell wall separation by preferential delignification of compound middle lamellae (CML) was not seen in decayed tracheids. It can be concluded that the Termovuoto TMW220 degrees c process has an impact on the delignification process of P. sanguineus at the cell wall level, which slows down the decay.
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| 9. |
- Kim, Jongsik, et al.
(author)
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Chemical and ultrastructural changes of ash Wood thermally modified (TMW) using the thermovacuum process: II. Immunocytochemical study of the distribution of noncellulosic polysaccharides
- 2015
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In: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 69, s. 615-625
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Journal article (peer-reviewed)abstract
- Following structural and cytochemical studies (Part I) on thermally modified ash wood (TMW) by the thermo-vacuum (Termovuoto) process, changes in the distribution of noncellulosic polysaccharides have been investigated in TMW treated for 3 h at 220 by means of immunogold localization methods. Pectins (homogalacturonan, rhamnogalacturonan-I) and xyloglucan were significantly degraded in compound middle lamella (CML), including the middle lamella cell corner regions (CML Xylan and mannan degradation were also visible in fiber cell walls. In particular, degradation of mannan was very significant and showed variation between cell wall regions even within the same cell wall. The degradation of pectins was more significant than that of hemicelluloses. In summary, results suggest that each noncellulosic polysaccharide may have a different degradation process in ash TMWs°C (TMW3 h, 220°C)cc), of all xylem cells after thermal modification.
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| 10. |
- Kim, Jongsik, et al.
(author)
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Chemical and ultrastructural changes of ash wood thermally modified using the thermo-vacuum process: I. Histo/cytochemical studies on changes in the structure and lignin chemistry
- 2015
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In: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 69, s. 603-613
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Journal article (peer-reviewed)abstract
- Changes in structure and lignin chemistry were investigated in ash wood thermally modified (TMW) by the thermo-vacuum (Termovuoto) process for 3 h at 190-220 degrees C by means of light, fluorescence, and transmission electron (TEM) microscopy combined with histo/cytochemistry. Variation in changes in native cell color in TMWs was positively correlated with differences in lignin content between cell types and cell wall regions in the reference wood. Histochemical staining showed increasing amounts of acidic groups in TMWs with different response to ethanol extraction between secondary cell walls and CMLcc (compound middle lamella/middle lamella cell corner) regions. Fluorescence microscopy of TMWs and references showed a difference in intensity and color emission of lignin autofluorescence, reflecting modification of lignin in TMWs. Changes in histochemistry and fluorescence were prominent at and above 200 degrees C. With TEM, increased intensity of lignin staining and distortion of fiber S-1 layers were detected in TMW treated for 3 h at 220 degrees C (TMW3 h, 220 degrees C). TMW3 h, 220 degrees C differed significantly in molecular ultrastructure of fiber cell walls compared to references, such as loss of the lamellar structure and size and distribution of lignin aggregates. The modification in CMLcc structure in ash TMW3 h, 220 degrees C is different from that of softwoods.
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