Conversion of milled pine wood by manganese peroxidase from Phlebia radiata

Purified manganese peroxidase (MnP) from the white-rot basidiomycete Phlebia radiata was found to convert in vitro milled pine wood (MPW) suspended in an aqueous reaction solution containing Tween 20, Mn(2+), Mn-chelating organic acid (malonate), and a hydrogen peroxide-generating system (glucose-glucose oxidase). The enzymatic attack resulted in the polymerization of lower-molecular-mass, soluble wood components and in the partial depolymerization of the insoluble bulk of pine wood, as demonstrated by high-performance size exclusion chromatography (HPSEC). The surfactant Tween 80 containing unsaturated fatty acid residues promoted the disintegration of bulk MPW. HPSEC showed that the depolymerization yielded preferentially lignocellulose fragments with a predominant molecular mass of ca. 0.5 kDa. MnP from P. radiata (MnP3) turned out to be a stable enzyme remaining active for 2 days even at 37 degrees C with vigorous stirring, and 65 and 35% of the activity applied was retained in Tween 20 and Tween 80 reaction mixtures, respectively. In the course of reactions, major part of the Mn-chelator malonate was decomposed (85 to 87%), resulting in an increase of pH from 4.4 to >6.5. An aromatic nonphenolic lignin structure (beta-O-4 dimer), which is normally not attacked by MnP, was oxidizible in the presence of pine wood meal. This finding indicates that certain wood components may promote the degradative activities of MnP in a way similar to that promoted by Tween 80, unsaturated fatty acids, or thiols.     

Comparison of usefulness of three types of artificial substrata (glass, wood and plastic) when studying settlement patterns of periphyton in lakes of different trophic status

Usefulness of three types of artificial substrata (glass, wood and plastic) was tested when studying settlement patterns of periphyton in lakes of different trophic status. Strictly eu-, meso- and oligotrophic lakes in central Sweden were chosen as objects of the study. Glass slides, glass tubes, pieces of plastic (PVC) and pieces of wood of similar dimensions were placed for 9 weeks in July-August vertically 3 cm above bottom at a total depth of ca. 30 cm. Substrata were located at well-illuminated places without any other submerged objects (like macrophytes and stones), which could potentially affect colonisation patterns by algae. Periphyton communities, which colonised both the glass tubes and the pieces of wood tested, were specific enough to enable a clear classification of the lakes studied in eu-, meso- and oligotrophic. Glass tubes turned out to be the most favourable substratum when investigating settlement patterns of periphyton in this study. Although also colonised by periphytic species, wood did not support the same diversity and abundance of species as glass did. No algae were detected on the plastics studied. The plastics were covered entirely by a slime layer of bacteria. It is discussed if the nature of plastics could have some inhibitory effects on algal growth or the slime layer itself may have prevented settlement of algal spores.     

Large wood and fluvial processes

1. Large wood forms an important component of woodland river ecosystems. The relationship between large wood and the physical characteristics of river systems varies greatly with changes in the tree species of the marginal woodland, the climatic and hydrological regime, the fluvial geomorphological setting and the river and woodland management context. 2. Research on large wood and fluvial processes over the last 25 years has focussed on three main themes: the effects of wood on flow hydraulics; on the transfer of mineral and organic sediment; and on the geomorphology of river channels. 3. Analogies between wood and mineral sediment transfer processes (supply, mobility and river characteristics that affect retention) are found useful as a framework for synthesising current knowledge on large wood in rivers. 4. An important property of wood is its size when scaled to the size of the river channel. ′Small′ channels are defined as those whose width is less than the majority of wood pieces (e.g. width < median wood piece length). `Medium' channels have widths greater than the size of most wood pieces (e.g. width < upper quartile wood piece length), and `Large' channels are wider than the length of all of the wood pieces delivered to them. 5. A conceptual framework defined here for evaluating the storage and dynamics of wood in rivers ranks the relative importance of hydrological characteristics (flow regime, sediment transport regime), wood characteristics (piece size, buoyancy, morphological complexity) and geomorphological characteristics (channel width, geomorphological style) in `Small', `Medium' and `Large' rivers. 6. Wood pieces are large in comparison with river size in `small' rivers, therefore they tend to remain close to where they are delivered to the river and provide important structures in the stream, controlling rather than responding to the hydrological and sediment transfer characteristics of the river. 7. For `Medium' rivers, the combination of wood length and form becomes critical to the stability of wood within the channel. Wood accumulations form as a result of smaller or more mobile wood pieces accumulating behind key pieces. Wood transport is governed mainly by the flow regime and the buoyancy of the wood. Even quite large wood pieces may require partial burial to give them stability, so enhancing the importance of the sediment transport regime. 8. Wood dynamics in `Large' rivers vary with the geometry of the channel (slope and channel pattern), which controls the delivery, mobility and breakage of wood, and also the characteristics of the riparian zone, from where the greatest volume of wood is introduced. Wood retention depends on the channel pattern and the distribution of flow velocity. A large amount is stored at the channel margins. The greater the contact between the active channel and the forested floodplain and islands, the greater the quantity of wood that is stored.     

Comparisons of SPORL and dilute acid pretreatments for sugar and ethanol productions from aspen

This study reports comparative evaluations of sugar and ethanol production from a native aspen (Populus tremuloides) between sulfite pretreatment to overcome recalcitrance of lignocellulose (SPORL) and dilute acid (DA) pretreatments. All aqueous pretreatments were carried out in a laboratory wood pulping digester using wood chips at 170°C with a liquid to oven dry (od) wood ratio (L/W) of 3:1 at two levels of acid charge on wood of 0.56 and 1.11%. Sodium bisulfite charge on od wood was 0 for DA and 1.5 or 3.0% for SPORL. All substrates produced by both pretreatments (except DA with pretreatment duration of 0) had good enzymatic digestibility of over 80%. However, SPORL produced higher enzymatic digestibility than its corresponding DA pretreatment for all the experiments conducted. As a result, SPORL produced higher ethanol yield from simultaneous saccharification and fermentation of cellulosic substrate than its corresponding DA pretreatment. SPORL was more effective than its corresponding DA pretreatment in reducing energy consumption for postpretreatment wood chip size-reduction. SPORL, with lower energy input and higher sugar and ethanol yield, produced higher sugar and ethanol production energy efficiencies than the corresponding DA pretreatment.     

Hydrogels obtained from an original catanionic system for efficient formulation of boron wood-preservatives

A new catanionic system associating amphiphilic carnosine (βAlaHisC8) and lauric acid forms supramolecular hydrogel at a very low concentration. This gel was investigated and we checked the validity of the concept of hydrogel utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) fosters improvement in the resistance of Scots pine sapwood subjected to water leaching toward the brown-rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood.     

Decaying wood is a sodium source for mountain gorillas

Like several other non-human primates, mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda consume decaying wood, an interesting but puzzling behaviour. This wood has little obvious nutritional value; it is low in protein and sugar, and high in lignin compared to other foods. We collected pieces of wood eaten and avoided by gorillas, and other foods consumed by gorillas, and measured their sodium content. Wood was substantially higher in sodium than other dietary items, and wood pieces from stumps eaten contained more sodium than those that were avoided. Wood represented only 3.9% of the wet weight food intake of gorillas, but contributed over 95% of dietary sodium, leading us to conclude that decaying wood is an important sodium source for Bwindi gorillas. Because sodium has been leached from the weathered soils characteristic of the subhumid and humid tropics, and because terrestrial plants generally do not require sodium, tropical herbivores, including gorillas, often encounter problems locating the sodium essential for their well-being. Decaying wood is an unexpected sodium source.     

A life cycle evaluation of wood pellet gasification for district heating in British Columbia

The replacement of natural gas combustion for district heating by wood waste and wood pellets gasification systems with or without emission control has been investigated by a streamlined LCA. While stack emissions from controlled gasification systems are lower than the applicable regulations, compared to the current base case, 12% and 133% increases are expected in the overall human health impacts for wood pellets and wood waste, respectively. With controlled gasification, external costs and GHG emission can be reduced by 35% and 82% on average, respectively. Between wood pellets and wood waste, wood pellets appear to be the better choice as it requires less primary energy and has a much lower impact on the local air quality.     

Incorporation of p-cresol into lignins via peroxidase-catalysed copolymerization in nonaqueous media

Lignin, the second most abundant biopolymer after cellulose, is a low value by-product of agricultural and wood conversion processes, including wood pulp manufacture. Copolymerization with phenols has the potential to convert by-product lignins to higher-value phenolic resins. In this initial investigation, we have studied the use of horseradish peroxidase (HRP) in aqueous dioxane to catalyse the grafting of p-cresol (p-methylphenol) onto milled wood lignin, kraft lignin, and a lignin selectively o-demethylated by a brown-rot fungus. Advantages of this system are (1) the mild reaction conditions employed and (2) the ability of HRP to function in the dioxane: water solutions which solubilize lignin. The reaction is monitored by gel permeation chromatography using a reaction system of [¹⁴C]-p-cresol with unlabeled lignins. We have found that optimal incorporation of cresol into high-molecular-weight polymer occurs at 50–70% dioxane in water under the conditions used; a maximum incorporation of ca. 4 mol% (e.g., p-cresol incorporated per C₉ lignin unit) was obtained. Blocking the phenolic hydroxyl groups of the lignin inhibits copolymerization, consistent with the proposed mechanism of phenoxy radical copolymerization for this reaction.     

The occurrence of myxomycetes in wood

Although the fruiting bodies of myxomycetes are commonly found associated with coarse woody debris in forest ecosystems throughout the world, there is no direct evidence that these organisms actually live within wood. In the research reported herein, surface sterilisation of pieces of wood taken from the branches of eight different tree species and the subsequent culturing of slivers of wood collected from within the interior of those branches clearly revealed the presence of the amoeboflagellates of myxomycetes. No evidence of the occurrence of plasmodia within wood was found, but amoeboflagellates emerged from 47 % of the wood slivers placed in culture.     

Wood construction more strongly shapes deadwood microbial communities than spatial location over 5 years of decay

Diverse communities of fungi and bacteria in deadwood mediate wood decay. While rates of decomposition vary greatly among woody species and spatially distinct habitats, the relative importance of these factors in structuring microbial communities and whether these shift over time remains largely unknown. We characterized fungal and bacterial diversity within pieces of deadwood that experienced 6.3–98.8% mass loss while decaying in common garden ‘rotplots’ in a temperate oak-hickory forest in the Ozark Highlands, MO, USA. Communities were isolated from 21 woody species that had been decomposing for 1–5 years in spatially distinct habitats at the landscape scale (top and bottom of watersheds) and within stems (top and bottom of stems). Microbial community structure varied more strongly with wood traits than with spatial locations, mirroring the relative role of these factors on decay rates on the same pieces of wood even after 5 years. Co-occurring fungal and bacterial communities persistently influenced one another independently from their shared environmental conditions. However, the relative influence of wood construction versus spatial locations differed between fungi and bacteria, suggesting that life history characteristics of these clades structure diversity differently across space and time in decomposing wood.     

Enhancing survival and subsequent infectivity of conidia of potential mycoherbistats using UV protectants

Ultraviolet radiation (UV) can reduce the effectiveness of fungi used for biological control; therefore, this study examined the photostabilising effect of water- and oil-soluble UV protectants on conidium germination of Plectosporium alismatis and Colletotrichum orbiculare, pathogens with potential as biocontrol agents, and the ability of conidia of C. orbiculare to cause disease. Formulation in riboflavin (1%), proline (1%), propyl gallate (1%), melanin (0.1%) and ascorbic acid (5%) increased the germination of UVB-exposed conidia of P. alismatis to levels found in the dark control without causing a delay in germination. Formulation in (a) pyridoxin (5%), (b) an nC24 mineral oil (5%), and (c) ECCO 1422 (5% in the mineral oil) also resulted in germination similar to the control but germination was delayed. Protection was provided to conidia of C. orbiculare treated with 1% aqueous solutions of proline and folic acid in vitro. Formulation of conidia of C. orbiculare in a 5% aqueous emulsion of the mineral oil and aqueous solutions of melanin (0.01%), proline and tyrosine (both at 1%) significantly increased anthracnose development above control levels on leaf discs of Xanthium spinosum exposed to UVB dose of 16.7 kJ m^-2. After exposure to natural sunlight at a UVB dose of 2.2 kJ m^-2, anthracnose development was greater on leaf discs inoculated with conidia of C. orbiculare formulated in 1% aqueous solutions of ascorbic acid (1%), proline (1%), tyrosine (1%) and melanin (0.01%), or in 5% aqueous emulsions of a canola-derived oil and the mineral oil than by conidia formulated in water alone. Therefore, a range of compounds can provide conidia with protection from UVB. Of these, propyl gallate and oils similar to the mineral oil are likely to be cost effective. Such formulations can be combined with suitable application times to increase mycoherbisitat efficiency.     

Conversion of Milled Pine Wood by Manganese Peroxidase from Phlebia radiata

Purified manganese peroxidase (MnP) from the white-rot basidiomycete Phlebia radiata was found to convert in vitro milled pine wood (MPW) suspended in an aqueous reaction solution containing Tween 20, Mn²⁺, Mn-chelating organic acid (malonate), and a hydrogen peroxide-generating system (glucose-glucose oxidase). The enzymatic attack resulted in the polymerization of lower-molecular-mass, soluble wood components and in the partial depolymerization of the insoluble bulk of pine wood, as demonstrated by high-performance size exclusion chromatography (HPSEC). The surfactant Tween 80 containing unsaturated fatty acid redsidues promoted the disintegration of bulk MPW. HPSEC showed that the depolymerization yielded preferentially lignocellulose fragments with a predominant molecular mass of ca. 0.5 kDa. MnP from P. radiata (MnP3) turned out to be a stable enzyme remaining active for 2 days even at 37°C with vigorous stirring, and 65 and 35% of the activity applied was retained in Tween 20 and Tween 80 reaction mixtures, respectively. In the course of reactions, major part of the Mn-chelator malonate was decomposed (85 to 87%), resulting in an increase of pH from 4.4 to >6.5. An aromatic nonphenolic lignin structure (β-O-4 dimer), which is normally not attacked by MnP, was oxidizible in the presence of pine wood meal. This finding indicates that certain wood components may promote the degradative activities of MnP in a way similar to that promoted by Tween 80, unsaturated fatty acids, or thiols.     

New Uses for Calcium Chloride Solution as a Mounting Medium

Fresh cross sections of stems [Psilotum nudum, Coleus blumei, and Pelargonium peltatum] and roots (Setcreasea purpurea) 120 μm thick were fixed in FPA₅₀ (formalin: propionic acid: 50% ethanol, 5:5:90, v/v) for 24 hr and stored in 70% ethanol. The sections were transferred to water and then to 1% phloroglucin in 20% calcium chloride solution plus either hydrochloric, nitric, or lactic acid in the following ratios of phloroglucin-CaCl₂ solution:acid: 25:4, 20:2, or 15:5. The sections were mounted on slides either in one of the three mixtures or in fresh 20% calcium chloride solution. A rapid reaction of the acid-phloroglucin with lignin produced a deep red color in tracheary elements and an orange-red color in sclerenchyma. Fixed and stored leaf pieces from Nymphaea odorata were autoclaved in lactic acid, washed in two changes of 95% ethanol, transferred to water, and treated with the three acid-phloroglucin-calcium chloride mixtures. The abundant astrosclereids stained an orange-red color similar to that of sclerenchyma in the sections. In addition, a new method is reported for specifically staining lignified tissues. When sections or leaf pieces are stained in aqueous 0.05% toluidine blue O, then placed in 20% calcium chloride solution, all tissues destain except those with lignified or partially lignified cell walls. Thus, toluidine blue O applied as described becomes a reliable specific test for lignin comparable to the acid-phloroglucin test.     

Pine wood carboxymethylation under microwave radiation

The use of microwave radiation was proposed for the intensification of the pine wood carboxymethylation process performed without prior separation into individual components. To obtain the carboxymethylated pine wood in the form of potassium salt, the pine wood was treated with potassium hydroxide and monochloroacetic acid in 2-propanol media. The composition and properties of the resulting products were studied. Carboxymethylated cellulose was extracted from the carboxymethylated pine wood. It was found that the increase of the microwave radiation power (from 210 to 700 W) and of the duration of the first and second carboxymethylation stages (20–30 sec) increases the content of carboxymethyl groups (18.3–25.6%). The solubility of the potassium salts of the carboxymethylated pine wood (10–18%) was abnormally low as compared with that of the sodium salts at similar content of carboxymethyl groups. The viscosity of the aqueous solutions of the carboxymethylated pine wood and the carboxymethyl cellulose extracted from it was studied. It is shown that the samples obtained using the microwave radiation power of 210 W are characterized by abnormal flow curves.     

Conversion of Japanese red pine wood (Pinus densiflora) into valuable chemicals under subcritical water conditions

A comparative study on the decomposition of Japanese red pine wood under subcritical water conditions in the presence and absence of phosphate buffer was investigated in a batch-type reaction vessel. Since cellulose makes up more than 40-45% of the components found in most wood species, a series of experiments were also carried out using pure cellulose as a model for woody biomass. Several parameters such as temperature and residence time, as well as pH effects, were investigated in detail. The best temperature for decomposition and hydrolysis of pure cellulose was found around 270 °C. The effects of the initial pH of the solution which ranged from 1.5 to 6.5 were studied. It was found that the pH has a considerable effect on the hydrolysis and decomposition of the cellulose. Several products in the aqueous phase were identified and quantified. The conditions obtained from the subcritical water treatment of pure cellulose were applied for the Japanese red pine wood chips. As a result, even in the absence of acid catalyst, a large amount of wood sample was hydrolyzed in water; however, by using phosphate buffer at pH 2, there was an increase in the hydrolysis and dissolution of the wood chips. In addition to the water-soluble phase, acetone-soluble and water-acetone-insoluble phases were also isolated after subcritical water treatment (which can be attributed mainly to the degraded lignin, tar, and unreacted wood chips, respectively). The initial wood:acid ratio in the case of reactions catalyzed by phosphate buffer was also investigated. The results showed that this weight ratio can be as high as 3:1 without changing the catalytic activity. The size of the wood chips as one of the most important experimental parameters was also investigated.     

Habitat preferences of oak-feeding xylophagous beetles in a temperate woodland: implications for forest history and management

Oaks host the richest fauna of saproxylic insect in Europe. We studied habitat preferences of two beetle families, Buprestidae and Cerambycidae, by rearing the beetles from standardised oak timber baits. Species density was higher in the understorey than in the canopy; and in sun-exposed baits if within the understorey. Insolation was the most important factor affecting the composition of reared assemblages (explaining ca. 30% of variation in the data), followed by vertical stratum (ca. 10%). Local dead wood volume had no effect. The high preference for sun-exposed wood located near the ground suggests that: (i) open-canopy woodlands had to be rather common in temperate Europe; (ii) oak-utilising xylophages would benefit from restoration of management practices such as coppicing or woodland pasture; (iii) the policy of increasing dead wood volume in commercial forests is principally correct, but its success will depend on dead wood location within the forests.     

Batch and continuous fermentation of succinic acid from wood hydrolysate by Mannheimia succiniciproducens MBEL55E

Batch and continuous cultures of Mannheimia succiniciproducens MBEL55E were carried out in a complex medium containing a NaOH-treated wood hydrolysate for the production of succinic acid. The wood hydrolysate based medium was treated with NaOH before sterilization to reduce the formation of inhibitory compounds. M. succiniciproducens MBEL55E utilized xylose as well as glucose in the wood hydrolysate based medium as a carbon source for the succinic acid production. In batch cultures, the final succinic acid concentration of 11.73 g l⁻¹ was obtained from the pre-treated wood hydrolysate based medium, resulting in a succinic acid yield of 56% and a succinic acid productivity of 1.17 g l⁻¹ h⁻¹, while the corresponding continuous cultures gave the succinic acid yield and productivity of 55% and 3.19 g l⁻¹ h⁻¹, respectively. These results suggest that succinic acid can be produced economically and efficiently by the fermentation of M. succiniciproducens MBEL55E from an inexpensive biomass-based wood hydrolysate.     

Modification of wood with Si compounds to limit boron leaching from treated wood and to increase termite and decay resistance

In this study, we tested tetraethoxysilane and methyltriethoxysilane as modifying silicon-based compounds for their potential to limit boron leachability from modified wood and to increase biological durability of the wood against fungi and termites. Both the silane compounds were used in silane state where acidified ethanol was added and stirred at ambient temperature for 30 min. We used two different processes for preservative treatments: double treatment and single treatment. In double treatment, the specimens from sugi wood were first treated with boric acid at 1% concentration and subsequently treated with the silanes. In single treatment, boric acid was mixed with the silane compounds in the silane state yielding 1% boric acid concentration. Subsequent to the treatments, wood specimens were subjected to laboratory leaching tests, and leachates were analyzed for boron content with an inductively coupled plasma (ICP) spectrometry. ICP analyses showed that silane treatments were able to limit boron leaching from treated wood by about 40% in all cases for each silane compound. Wood specimens were then subjected to laboratory termite and decay resistance tests using the subterranean termites, Coptotermes formosanus, and the wood decaying fungi, Fomitopsis palustris and Trametes versicolor. Termite and fungal decay resistance tests revealed that resistance of modified wood with the silane and boron compounds increased when compared to untreated and boron-only treated wood specimens. More in-depth studies on the mechanisms of interactions between the silicon compounds, boron elements and wood components are in progress.     

Wood remains from Tel Nami,a middle bronze IIa and late bronze IIb port,local exploitation of trees and levantine cedar trade

Thirteen Middle Bronze Age IIa and four Late Bronze Age IIb (ca. 1950-1750 B.C. and thirteenth century, B.C., respectively)pieces of charcoal or water logged wood were found in the recent excavations of Tel Nami, a small port on the coast near Mount Carmel, Israel. These includedCedrus libani (cedar of Lebanon) (three samples), and local tree species that still grow today in the vicinity of the site—Pinus halepensis (Aleppo pine) (one sample),Olea europaea (olive tree) (five samples),Quercus calliprinos (kermes oak) (three samples),Quercus ithaburensis (Mt. Tabor oak) (four samples), andQuercus sp. (one sample). The discovery of Cedrus libani in a Middle Bronze Age IIa port is one of the earliest published examples of cedar wood from Israel. Together with other artifactual evidence for maritime trade from Tel Nami, this find suggests that a maritime trade in cedar wood existed along the Levantine coast.     

Efficacy of ozone fumigation for laboratory animal sanitation]

Ozone resistance of spores of 2 strains of Bacillus isolated from laboratory animals was examined. Each of 0.02 ml of phosphate-buffered saline at pH 7.0 containing 10(6) Bacillus spores was dropped onto sterilized filter strips, wood chip bedding, pellets of diet, cloth pieces and stainless steel plates. After drying at room temperature, the test materials were exposed to ozone gas of different concentrations at 90% RH. Exposure to 200ppm ozone for 6 hours was sufficient to kill spores in filter strips, but a little higher concentration or a little longer period of ozone fumigation was necessary for sterilization of wood chips, cotton cloth pieces and steel plates. The present results indicated that 600ppm ozone fumigation for 6 hours might be effective for routine sterilization of cages, wood bedding, working clothes and other materials used in laboratory animal facilities. However, exposure to ozone gas of 500 or 1,000 ppm for 6 hours or 200 ppm for 24 hours could not kill spores in pellets of diet, suggesting that dietary protein inhibited the bactericidal activity of ozone.