Lignin depolymerization/repolymerization and its critical role for delignification of aspen wood by steam explosion

Steam explosion is an important process for the fractionation of biomass components. In order to understand the behaviour of lignin under the conditions encountered in the steam explosion process, as well as in other types of steam treatment, aspen wood and isolated lignin from aspen were subjected to steam treatment under various conditions. The lignin portion was analyzed using NMR and size exclusion chromatography as major analytical techniques. Thereby, the competition between lignin depolymerization and repolymerization was revealed and the conditions required for these two types of reaction identified. Addition of a reactive phenol, 2-naphthol, was shown to inhibit the repolymerization reaction strongly, resulting in a highly improved delignification by subsequent solvent extraction and an extracted lignin of uniform structure.     

Thermal effects on acid hydrolysis of cellulose

Acid-catalysed hydrolysis of cellulose is a technically feasible process. Cellulosic biomass often requires size reduction which imparts additional cost to the hydrolysis process. A simplified heterogeneous model was developed to study the effect of non-uniform temperature distribution inside wood chips on the hydrolysis process. Increasing particle size was found to result in lower glucose yields and higher reaction times. The effect was more pronounced at higher reaction temperatures. Mathematical correlations were found to quantify this effect.     

Laccase-induced HBT-grafting to milled beech wood reduces unspecific protein adsorption

Lignocellulosic biomass is a ubiquitous and renewable feedstock for the production of platform chemicals and biofuels. Typically, this recalcitrant biomass is pretreated by physico-chemical techniques causing disintegration and delignification. An additional treatment with laccase-mediator-systems (LMS) has been found to further improve the subsequent enzymatic cellulose hydrolysis. The aim of this study was to investigate the impact of different LMS on the glucose yield of a subsequent hydrolysis of treated beech wood and to elucidate the underlying effect of LMS treatment. The mediators 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 1-hydroxybenzotriazol (HBT) and syringaldehyde were evaluated, but an enhancing effect of LMS treatment on beech wood hydrolysis was only found for HBT. In mass spectrometry analysis of the acid hydrolysate of LMS-treated samples, the mediator HBT could be found in the lignin samples, suggesting a grafting reaction. The fluorescent protein mCherry was used as a reporter for unspecific protein adsorption to biomass samples. LMS treatment with HBT reduced the unspecific adsorption of mCherry to raw beech wood by about 50%, suggesting that the HBT grafting to beech wood lignin decreased the unproductive cellulase binding. In summary, the reduction of unspecific protein adsorption by biomass surface modification with laccase-HBT treatment is proposed to be the underlying mechanism for increased cellulose conversion.     

Pre-treatment of Pinus radiata substrates by basidiomycetes fungi to enhance enzymatic hydrolysis

Pre-treatment is important step prior to enzymatic hydrolysis of ligno-cellulosic biomass in order to obtain renewable carbon source ca. glucose. Pinus radiata biomass including wood blocks, wood chips and steam exploded wood (SEW) were used to investigate the effect of fungal pre-treatment on glucose yield. Comparison was made using one white-rot fungus (Trametes versicolor) and three brown-rot fungi (Coniophora puteana, Antrodia xantha and Oligoporus placenta). This is the first study where SEW was treated with basidiomycetes and subsequent enzymatic hydrolysis gave 5 g glucose/l which is an order of magnitude greater compared to control biomass (0.5 g glucose/l). This enhanced glucose yield is due to the novel pre-treatment sequence used in this study.     

Analysis of Biomass Composition Using High-Resolution Thermogravimetric Analysis and Percent Bark Content for the Selection of Shrub Willow Bioenergy Crop Varieties

Rapid determination of biomass composition is critical for the selection of shrub willow varieties with optimized biomass properties for conversion into fuels or chemicals. In order to improve the process for identifying and selecting shrub willow clones with distinct biomass composition, high-resolution thermogravimetric analysis (HR-TGA) was developed as a rapid, low-cost method for analyzing large numbers of willow biomass samples. In order to validate the HR-TGA method, bulk biomass collected from 2-year-old stems of a selected set of 25 shrub willow clones was analyzed using traditional wet chemistry techniques in addition to HR-TGA. The results of the wet chemistry and the HR-TGA method were compared using regression analysis resulting in R-squared values above 0.7 for the three main wood components, cellulose, hemicellulose, and lignin. Bark was removed from duplicate stem samples of the same clones, the proportion of bark was determined, and the debarked wood was used for HR-TGA analysis of composition. While there were significant differences in the proportions of lignin and cellulose in debarked wood compared to bulk biomass, as well as significant differences in bark percentage among clones, there was no correlation between bark percentage and bulk biomass component analysis. This work validates the effectiveness, precision, and accuracy of HR-TGA as a reasonably high-throughput method for biomass composition analysis and selection of shrub willow bioenergy crop varieties.     

A new process for the esterification of wood by reaction with vinyl esters

A novel route to wood modification by transesterification of vinyl esters is developed in the current study. The reaction between varied saturated and unsaturated vinyl esters and the hydroxyl groups of maritime pine sapwood (Pinus pinaster Soland) was examined using potassium carbonate as a catalyst. The esterification of wood was investigated by weight percent gain calculations (WPG), Fourier-transform infrared spectroscopy (FTIR) and ¹³C cross-polarization with magic-angle spinning nuclear magnetic resonance spectroscopy (¹³C CP–MAS NMR). Differences in the rates of modification were noted, depending on the vinyl ester used, but relatively high yields were obtained in all cases. The infrared and NMR spectra of the different esterified samples were analysed in detail and the assignment of the signals corresponding to the grafted acyl groups confirmed that esterification occurred.     

Investigations into the pyrolytic behaviour of coal/biomass blends using thermogravimetric analysis

Investigations into the pyrolytic behaviour during co-pyrolysis of coal, biomass materials and coal/biomass blends prepared at different ratios (10:90, 20:80, 30:70 and 50:50) have been conducted using a thermogravimetric analysis (TGA) apparatus. The coal sample selected was Collie sub-bituminous coal from Western Australia, while wood waste (WW) and wheat straw (WS) were used as biomass samples. Three thermal events were identified during the pyrolysis. The first two were dominated by the biomass pyrolysis, while the third was linked to the coal pyrolysis, which occurred at much higher temperatures. No interactions were seen between the coal and biomass during co-pyrolysis. The pyrolytic characteristics of the blends followed those of the parent fuels in an additive manner. Among the tested blends, 20:80 blends showed the lowest activation energies of 90.9 and 78.7 kJmol(-1) for coal/WW and coal/WS blends respectively. The optimum blend ratio for pyrolysis of coal/WS was 50:50 with a high degradation rate in all the thermal events and a higher mass loss over the course of the co-pyrolysis compared to coal/WW blends examined. The reaction orders in these experiments were in the range of 0.21-1.60, thus having a significant effect on the overall reaction rate. Besides the pyrolysis of coal alone, the 50:50 coal/biomass blends had the highest reaction rate, ranging 1x10(9)-2x10(9) min(-1). The experimental results may provide useful data for power generation industries for the development of co-firing options with biomass.     

A Cross-System Comparison of Bacterial and Fungal Biomass in Detritus Pools of Headwater Streams

The absolute amount of microbial biomass and relative contribution of fungi and bacteria are expected to vary among types of organic matter (OM) within a stream and will vary among streams because of differences in organic matter quality and quantity. Common types of benthic detritus [leaves, small wood, and fine benthic organic matter (FBOM)] were sampled in 9 small (1st-3rd order) streams selected to represent a range of important controlling factors such as surrounding vegetation, detritus standing stocks, and water chemistry. Direct counts of bacteria and measurements of ergosterol (a fungal sterol) were used to describe variation in bacterial and fungal biomass. There were significant differences in bacterial abundance among types of organic matter with higher densities per unit mass of organic matter on fine particles relative to either leaves or wood surfaces. In contrast, ergosterol concentrations were significantly greater on leaves and wood, confirming the predominance of fungal biomass in these larger size classes. In general, bacterial abundance per unit organic matter was less variable than fungal biomass, suggesting bacteria will be a more predictable component of stream microbial communities. For 7 of the 9 streams, the standing stock of fine benthic organic matter was large enough that habitat-weighted reach-scale bacterial biomass was equal to or greater than fungal biomass. The quantities of leaves and small wood varied among streams such that the relative contribution of reach-scale fungal biomass ranged from 10% to as much as 90% of microbial biomass. Ergosterol concentrations were positively associated with substrate C:N ratio while bacterial abundance was negatively correlated with C:N. Both these relationships are confounded by particle size, i.e., leaves and wood had higher C:N than fine benthic organic matter. There was a weak positive relationship between bacterial abundance and streamwater soluble reactive phosphorus concentration, but no apparent pattern between either bacteria or fungi and streamwater dissolved inorganic nitrogen. The variation in microbial biomass per unit organic matter and the relative abundance of different types of organic matter contributed equally to driving differences in total microbial biomass at the reach scale.     

Elevated atmospheric CO2 alters wood production, wood quality and wood strength of Scots pine (Pinus sylvestris L) after three years of enrichment

Scots pine ( Pinus sylvestris L.) trees were grown in open top chambers for three years under ambient and elevated CO₂ concentrations. The trees were aged 3 y at the beginning of the CO₂ exposure, and the effects of the treatment on total stem volume, stem wood biomass, wood quality and wood anatomy were examined at the end of the exposure. The elevated CO₂ treatment lead to a 49% and 38% increase in stem biomass and stem wood volume, respectively. However, no significant effects of the elevated CO₂ treatment on wood density were observed, neither when green wood density was estimated from stem biomass and stem volume, nor when oven-dry wood density was measured on small wood samples. Under elevated CO₂ significantly wider growth rings were observed. The effect of elevated CO₂ on growth ring width was primarily the result of an increase in earlywood width. Wood compression strength decreased under elevated CO₂ conditions, which could be explained by significantly larger tracheids and the increased earlywood band, that has thinner walls and larger cavities. A significant decrease of the number of resin canals in the third growth ring was observed under the elevated treatment; this might indicate that trees produced and contained less resin, which has implications for disease and pest resistance. So, although wood volume yield in Scots pine increased significantly with elevated CO₂ after three years of treatment, wood density remained unchanged, while wood strength decreased. Whilst wood volume and stem biomass production may increase in this major boreal forest tree species, wood quality and resin production might decrease under future elevated CO₂ conditions.     

Ecology of coarse wood decomposition by the saprotrophic fungus <Emphasis Type="Italic">Fomes fomentarius</Emphasis>

Saprotrophic wood-inhabiting basidiomycetes are the most important decomposers of lignin and cellulose in dead wood and as such they attracted considerable attention. The aims of this work were to quantify the activity and spatial distribution of extracellular enzymes in coarse wood colonised by the white-rot basidiomycete Fomes fomentarius and in adjacent fruitbodies of the fungus and to analyse the diversity of the fungal and bacterial community in a fungus-colonised wood and its potential effect on enzyme production by F. fomentarius. Fungus-colonised wood and fruitbodies were collected in low management intensity forests in the Czech Republic. There were significant differences in enzyme production by F. fomentarius between Betula pendula and Fagus sylvatica wood, the activity of cellulose and xylan-degrading enzymes was significantly higher in beech wood than in birch wood. Spatial analysis of a sample B. pendula log segment proved that F. fomentarius was the single fungal representative found in the log. There was a high level of spatial variability in the amount of fungal biomass detected, but no effects on enzyme activities were observed. Samples from the fruiting body showed high β-glucosidase and chitinase activities compared to wood samples. Significantly higher levels of xylanase and cellobiohydrolase were found in samples located near the fruitbody (proximal), and higher laccase and Mn-peroxidase activities were found in the distal ones. The microbial community in wood was dominated by the fungus (fungal to bacterial DNA ratio of 62-111). Bacterial abundance composition was lower in proximal than distal parts of wood by a factor of 24. These results show a significant level of spatial heterogeneity in coarse wood. One of the explanations may be the successive colonization of wood by the fungus: due to differential enzyme production, the rates of biodegradation of coarse wood are also spatially inhomogeneous.     

The kinetics of Lagenidium giganteum growth in liquid and solid cultures

AIMS: Production of the mosquito biolarvacide Lagenidium giganteum in solid culture has been proposed as an economic alternative to production in liquid culture because of observations of improved shelf life and efficacy upon storage. Understanding the differences between these production systems and estimating growth rate in solid culture are important for commercialization. In order to address these needs a logistic model was developed to describe the growth kinetics of L. giganteum produced in solid and liquid cultures. METHODS AND RESULTS: Kinetic parameters in the logistic model were estimated by nonlinear regression of CO2 evolution rate (CER) and biomass data from solid and liquid cultivation experiments. Lagenidium giganteum biomass was measured using DNA extracted directly from samples. The logistic model was fit to experimental biomass and CER data with low standard errors for parameter estimates. The model was validated in two independent experiments by examining prediction of biomass using on-line CER measurements. CONCLUSIONS: There were significant differences between maximum biomass density, maintenance coefficients, and specific growth rates for liquid and solid cultures. The maximum biomass density (mg dw ml-1) was 11 times greater for solid cultivation compared with liquid cultivation of L. giganteum; however, the maintenance coefficient (mg CO2 h-1 (mg dw)-1) was six times greater for liquid cultivation than in solid cultivation. The specific growth rate at 30 degrees C was approximately 30% greater in liquid cultivation compared with solid cultivation. Slower depletion of substrate and lower endogenous metabolism may explain the longer shelf life of L. giganteum produced in solid culture. SIGNIFICANCE AND IMPACT OF THE STUDY: A simple logistic model was developed which allows real-time estimation of L. giganteum biomass from on-line CER measurements. Parameter estimates for liquid and solid cultivation models also elucidated observations of longer shelf life for production in solid culture.     

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood

Context

Wood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing). However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass.

Methods

Radial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood).

Results

Wood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm^-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm^-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity variance was explained by species only (45%) followed by a redundant part between species and regeneration guilds (36%). Despite substantial variation in wood specific gravity profiles among species and regeneration guilds, we found that values from the outer wood were strongly correlated to values from the whole profile, without any significant bias. In addition, we found that wood specific gravity from the DRYAD global repository may strongly differ depending on the species (up to 40% for Dialium pachyphyllum).

Main Conclusion

Therefore, when estimating forest biomass in specific sites, we recommend the systematic collection of outer wood samples on dominant species. This should prevent the main errors in biomass estimations resulting from wood specific gravity and allow for the collection of new information to explore the intraspecific variation of mechanical properties of trees.     

The effects of mixing on bioprocesses. Concentration distributions and mechanical shear stress

The effects of mixing on batch alcohol fermentation of diluted solutions of starch hydrolysate is studied. The results of a limited number of samples simultaneously drawn at different locations in the reactor and after different reaction times have been used in a simple mathematical model to provide a picture of the concentration distributions within the reaction environment. The optimal mixing conditions for the fermentation are met at rotation speeds between 1.7 and 5.0 s^?1, while the broth homogeneity obviously increases indefinitely with increasing this parameter. This suggests the existence of a shear stress for the biomass, whose effect increases with the application time and seems to affect the process mainly at the end of the fermentation.     

The Role of Biomass Composition and Steam Treatment on Durability of Pellets

Steam treatment has been reported to improve the durability of wood pellet likely by changing the physical and chemical structures of wood particles, but published literature is inconclusive about which structure change is the major reason for enhanced durability. In this work, steam treatment was combined either with alkaline or with SO₂ to study. The solids obtained after steam treatments along with a control sample were dried and each was compacted into pellets. The pellets were then tested for durability. Steam treatment alone dominated improvements in durability. The pellet durability increased with the amount of xylose, but xylose performed better in the pellet from raw poplar than did in the pellet from treated poplar. Water-soluble components contributed a maximum 4% of the durability of poplar pellets. The addition of lignin and sugars to substrates after steam treatment did not improve durability significantly. The surface modification that took place as a result of size reduction during steam treatment was the major reason, contributing about 50% of the durability of the pellet from steam-treated poplar. The acidity of steam treatment slightly affected the relative contributions of these structure changes on the durability. The new knowledge helps tailor the chemical and/or mechanical pretreatment involved in pelleting biomass to durable pellets.     

Effects of radial growth, tree age, climate, and seed origin on wood density of diverse jack pine populations

Several models of the effects of silviculture, radial growth, and tree age on wood density have been developed, but they have rarely considered the roles of diverse seed origins and climate. We developed a model to test the effects of radial growth, tree age, climate, and seed-source origins on wood density in 21 diverse populations of jack pine in a common garden in Petawawa, Ontario, Canada over the last 24 years using a linear mixed-effects model. Although we found significant differences in wood density among diverse seed origins, there were no differences between seed origins having the same ring age and ring width, indicating an indirect effect on wood density of seed-source origin via radial growth. High variation in wood density among trees within the same population and between populations indicated high genetic control of wood density. The climate effect was significant on wood density in all populations, but smaller when radial growth was controlled. Climate effect did not differ significantly among populations. Precipitation in July negatively affected latewood density, whereas precipitation in May in the current year and September of the previous year negatively affected earlywood density. We concluded that a single model of jack pine wood density and radial growth could be used, either controlling for climate effects or not, as the relationship between wood density and radial growth is preserved among the diverse populations, and the climate effect controlling for radial growth in the model was only slight.     

Wood durability of home-garden teak against brown-rot and white-rot fungi

Natural decay resistance of teak wood grown in home-garden forestry and the factors influencing decay resistance were determined in comparison with that of a typical forest plantation. Accelerated laboratory tests were conducted on 1800 wood samples drawn from 15 trees of three planted sites. Analysis of variance based on a univariate mixed model showed that planted site, fungal species, and their interaction terms were important sources of variation in decay resistance. With increasing decay resistance from centre to periphery of the heartwood, radial position was a critical factor and the interaction effect of fungal species × radial position was significant in influencing the durability. No significant differences were found in decay resistance either between the opposite radii or due to the various possible interaction terms of radii with the site, fungal species and radial position. There were significant differences in decay resistance against brown-rot fungi between wet and dry sites of home-garden teak although differences against white-rot fungi were non-significant among the three planted sites. Polyporus palustris was the more aggressive brown-rot fungus than Gloeophyllum trabeum. The higher susceptibility of wet site home-garden teak to brown-rot decay was associated with a paler colour of the wood and lower extractive content.     

Effect of initial fertilisation on biomass and nutrient contentof Norway spruce and Douglas-fir plantations at the same site

Norway spruce (NS) and Douglas-fir (DF) are among the main species used for production forestry in France. In low-elevation mountains and under-acidic conditions, they often occupy the same ecological situations. It is therefore of paramount interest to have a good understanding of how the two species behave under similar conditions and how they react to site improvement by fertilisation. The study stands are part of an experimental stand located in the estate forest of Breuil-Chenue in the Morvan (east central part of France). Its aim is to compare the impact of change in species on ecosystem functions. Destructive sampling of 10 trees per stand, distributed over the whole spectrum of inventoried classes of circumference at breast height (c _1.30), was carried out within four stands, e.g., fertilised and control (non-fertilised) NS; fertilised and control (non-fertilised) DF. Allometric relationships between c _1.30 and biomass or nutrient content per tree compartment were calculated. These equations were applied to the stand inventory for quantifying stand biomass and nutrient content on a hectare basis. The standard deviations of results were estimated using Monte-Carlo simulations. Specific emphasis was given to explain the origin of differences observed between species and treatments, i.e., changes in carbon allocation leading to specific allometric relationships, changes in stand structure (tree size distributions) and changes in stand density due to mortality.DF was more productive than NS (+28% for total tree biomass, +50% for ligneous biomass and +53% for stem wood). Both NS and DF were affected by fertilisation but in the case of NS, effects on the crown_c _1.30 relationship and on average tree growth were predominant while in the case of DF, the stem_c _1.30 relationship and stand density were affected by changes in soil fertility. The general fertilisation effect was an increment of 40% of ligneous dry matter for DF and only 22% for NS. In both cases, the amount of wood biomass produced per unit of leaf biomass (on a tree basis and, to a lesser extent, on a per hectare basis) was greater in fertilised plots. However, in the case of NS, the same amount of wood biomass was produced from a smaller quantity of leaves while in the case of DF, the same amount of leaves produced more wood biomass.The amount of nutrients in total ligneous biomass was higher for N, P and K, but lower for Ca and Mg, in DF than in NS. A high variability was observed between nutrient content of the different compartments, e.g., DF < NS for needles (except Mg), DF < NS for K, Ca and Mg for stem wood and DF > NS for N and P of stem wood. Fertilisation did not considerably change the hierarchy. On the basis of this study, all the indexes concerning stand production, wood density, nutrient use efficiency and response to fertilisation gave a net advantage to DF. This information is highly relevant for both ecological and practical purposes.     

Amino acid makeup of feed yeasts grown on a wood hydrolysate with a varying nitrogen, phosphorus and potassium content

The content of "raw protein" (N2X6.25), amino acids and fat in the biomass of yeast Candida scottii Tul-6 grown on wood hydrolysate with varying content of nitrogen, phosphorus and potassium was measured. Changes in the content of protein, total amino acids and fat in the biomass of yeast grown on the hydrolysate with a deficiency or an excess of the above macroelements were revealed.     

Nutrient dynamics of vegetation and detritus following two intensities of fire in the New Jersey pine barrens

The nutrient dynamics of upland forest sites in the New Jersey Pine Barrens exposed to different fire intensities were determined. Nutrient concentrations and inventories in biomass, litter, humus, and standing dead wood were determined for an unburned site, two sites burned by severe wildfire and two sites burned by light prescribed burning. Humus nutrient levels were similar among sites despite differing fire histories. Amounts of calcium, magnesium, and potassium in biomass and in litter were lower in wildfire sites than in prescribed burn sites, all of which were lower than the control. Standing dead wood nutrient levels were much higher in the wildfire sites than in the other three sites. Output of nutrients to groudwater correlated poorly with the amounts of nutrients retained in humus or standing dead wood; however strong inverse correlations were found between nutrient output and nutrient storage in biomass or biomass plus litter and humus. These results emphasize the central role of nutrient immobilization in regrowing biomass in after fire on nutrient poor soils.     

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.