Effects of pretreatment on morphology, chemical composition and enzymatic digestibility of eucalyptus bark: a potentially valuable source of fermentable sugars for biofuel production – part 1

Abstract Background In recent years, the growing demand for biofuels has encouraged the search for different sources of underutilized lignocellulosic feedstocks that are available in sufficient abundance to be used for sustainable biofuel production. Much attention has been focused on biomass from grass. However, large amounts of timber residues such as eucalyptus bark are available and represent a potential source for conversion to bioethanol. In the present paper, we investigate the effects of a delignification process with increasing sodium hydroxide concentrations, preceded or not by diluted acid, on the bark of two eucalyptus clones: Eucalyptus grandis (EG) and the hybrid, E. grandis x urophylla (HGU). The enzymatic digestibility and total cellulose conversion were measured, along with the effect on the composition of the solid and the liquor fractions. Barks were also assessed using Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), X-Ray diffraction, and scanning electron microscopy (SEM). Results Compositional analysis revealed an increase in the cellulose content, reaching around 81% and 76% of glucose for HGU and EG, respectively, using a two-step treatment with HCl 1%, followed by 4% NaOH. Lignin removal was 84% (HGU) and 79% (EG), while the hemicellulose removal was 95% and 97% for HGU and EG, respectively. However, when we applied a one-step treatment, with 4% NaOH, higher hydrolysis efficiencies were found after 48 h for both clones, reaching almost 100% for HGU and 80% for EG, in spite of the lower lignin and hemicellulose removal. Total cellulose conversion increased from 5% and 7% to around 65% for HGU and 59% for EG. NMR and FTIR provided important insight into the lignin and hemicellulose removal and SEM studies shed light on the cell-wall unstructuring after pretreatment and lignin migration and precipitation on the fibers surface, which explain the different hydrolysis rates found for the clones. Conclusion Our results show that the single step alkaline pretreatment improves the enzymatic digestibility of Eucalyptus bark. Furthermore, the chemical and physical methods combined in this study provide a better comprehension of the pretreatment effects on cell-wall and the factors that influence enzymatic digestibility of this forest residue.

Efeito da idade e posição de amostragem na densidade e características anatômicas da madeira de Eucalyptus grandis

O conhecimento das variações das características da madeira produzida pelas árvores de eucalipto em função da idade e posição no tronco é fundamental para o seu uso adequado. O presente trabalho teve como objetivo avaliar a influência da idade e das posições longitudinal na densidade básica e radial nas características anatômicas do lenho das árvores de Eucalyptus grandis plantadas no espaçamento 3x2 m e fertilizadas com adubação comercial no plantio, 6º, 12° mês. Foram selecionadas, de acordo com a distribuição de área basal, quinze árvores de eucalipto com 24, 36 e 72 meses de idade, sendo 5 árvores/idade, e cortados discos do lenho a 1,30 m da altura do solo (DAP) para as determinações das dimensões das fibras (comprimento, espessura da parede, diâmetro do lume e largura total) e vasos (diâmetro tangencial, frequência e área ocupada) e em diferentes alturas fixas do tronco para a determinação da densidade básica. A densidade básica do lenho aumentou de 0,43 g.cm-3 para 0,46 g.cm-3 com o avanço da idade das árvores, apresentando um modelo de variação longitudinal, comum as três idades, caracterizado pelo decréscimo da base-3m (0,42-0,49 g.cm-3 0,40-0,46 g.cm-3) e posterior aumento até a extremidade (0,46 g.cm-3 0,54 g.cm-3) do tronco. As dimensões das fibras e dos vasos apresentaram variações tanto em relação à idade quanto no sentido medula-casca. O comportamento e as variações das características do lenho das árvores de eucalipto indicam que o meristema cambial está formando, até este período, o lenho denominado de juvenil.

Effect of thermal treatment on the chemical characteristics of wood from Eucalyptus grandis W. Hill ex Maiden under different atmospheric conditions

Thermal treatment (thermal rectification) is a process in which technological properties of wood are modified using thermal energy, the result of which is often value-added wood. Thermally treated wood takes on similar color shades to tropical woods and offers considerable resistance to destructive microorganisms and climate action, in addition to having high dimensional stability and low hygroscopicity. Wood samples of Eucalyptus grandis were subjected to various thermal treatments, as performed in presence (140ºC; 160ºC; 180ºC) or in absence of oxygen (160ºC; 180ºC; 200ºC) inside a thermal treatment chamber, and then studied as to their chemical characteristics. Increasing the maximum treatment temperatures led to a reduction in the holocellulose content of samples as a result of the degradation and volatilization of hemicelluloses, also leading to an increase in the relative lignin content. Except for glucose, all monosaccharide levels were found to decrease in samples after the thermal treatment at a maximum temperature of 200ºC. The thermal treatment above 160ºC led to increased levels of total extractives in the wood samples, probably ascribed to the emergence of low molecular weight substances as a result of thermal degradation. Overall, it was not possible to clearly determine the effect of presence or absence of oxygen in the air during thermal treatment on the chemical characteristics of the relevant wood samples.

In vitro organogenesis of Eucalyptus grandis: effects of boron and calcium

The in vitro organogenesis of woody species plays an essential role in the improvement of forest products by providing saplings with high commercial value. Furthermore, mineral nutrition plays an important role in the induction of organogenic responses. The objective of this study was to evaluate the effects of boron and calcium in the organogenesis of nodal segments from seedlings of Eucalyptus grandis growing under in vitro conditions. The concentration of boron and calcium in MS medium was modified to induce organogenic responses in 45-day-old nodal segments used as explants. After 60 days, the fresh weight, dry weight, ratio of fresh and dry weight, relative water content and relative matter content accumulated by the explants were evaluated. The concentrations of boron and calcium in the culture medium influenced the in vitro organogenic control of Eucalyptus grandis. Reduced combinations of boron and calcium induced callus formation and dry matter accumulation in the explants. A boron concentration of 100% (1.10 mg L-1) combined with 100% (119.950 mg L-1) and 200% (239.900 mg L-1) of calcium, and 200% (2.20 mg L-1) of boron combined with 100% (119.950 mg L-1) of calcium allowed the induction of well-developed buds, which can be used for the regeneration of micro-plants.

Effects of conifer sawdust, hardwood sawdust, and peat on soil properties and a barefoot conifer seedling development

Organic amendments are commonly used to improve tree nursery soil conditions for increased seedling growth. However, few studies compare organic amendments effects on soil conditions, and fewer compare subsequent effects on seedling growth. The effects of three organic amendments on soil properties and seedling growth were investigated at the USDA Forest Service J.W. Toumey Nursery in Watersmeet, MI. Pine sawdust (red pine, Pinus resinosa), hardwood sawdust (maple, Acer spp. and aspen, Populus spp.), and peat were individually incorporated into a loamy sand nursery soil in August, 2006, and soil properties were sampled periodically for the next 14 months. Jack (Pinus banksiana), red, and white pine (Pinus strobus) were sown into test plots in June, 2007 and sampled for growth responses at the end of the growing season. It is hypothesized; pine sawdust and peat can be used as a satisfactory soil amendment to improve soil conditions and produce high quality seedlings, when compared to hardwood sawdust in bareroot nursery soils. This study has the potential to reduce nursery costs while broadening soil amendment options. The addition of peat and pine sawdust increased soil organic matter above control soil conditions after 14 months. However, hardwood sawdust-amended soils did not differ from control soils after same time period. High N concentrations in peat increased total soil N over the other treatments. Similarly, the addition of peat increased soil matric potential and available water over all other treatments. Seedlings grew tallest with the largest stem diameter, and had the largest biomass in both control soil and soil amended with peat, compared to either sawdust treatment. Seedlings grown in peat-amended soils had higher N concentrations than those grown in soils treated with pine sawdust, though neither was different from seedlings grown in control or hardwood sawdust-amended soils. Overall, peat is a well suited organic soil amendment for the enhancement of soil properties, but no amendments were able to increase one-year seedling growth over control soils.

VOLUME YIELDS OF SMALLHOLDER Eucalyptus grandis W. HILL EX MAIDEN STANDS IN EASTERN PARAGUAY

Smallholders in eastern Paraguay plant small stands of Eucalyptus grandis W. Hill ex Maiden intended for sale on the local market. Smallholders have been encouraged to plant E. grandis by local forestry extension agents who offer both forestry education and incentive programs. Smallholders who practice recommended forestry techniques geared towards growing large diameter trees of good form are financially rewarded by the local markets which desire saw log quality trees. The question was posed, are smallholders engaging in recommended silvicultural practices and producing reasonable volume yields? It was hypothesized that smallholders, having received forestry education and having financial incentives from the local market, would engage in silvicultural practices resulting in trees of good form and volume yields that were reasonable for the local climate and soil characteristics. Yield volume results from this study support this hypothesis. Mean volume yield was estimated at 70 cubic meters per hectare at age four and 225 cubic meters per hectare at age eight. These volume yields compare favorably to volume yields from other studies of E. grandis grown in similar climates, with similar stocking levels and site qualities.

Características palinológicas de mieles de eucalipto (Eucalyptus sp.) y tréboles (Trifolium sp.) provenientes de la Provincia Fitogeográfica Pampeana Argentina

El objetivo de este trabajo fue estudiar el perfil polínico de mieles de tréboles y de eucalipto de la Provincia Fitogeográfica Pampeana Argentina, con el fin de contribuir a su caracterización palinológica. Se realizó un análisis polínico cualitativo y se aplicaron técnicas estadísticas descriptivas y multivariadas, para conocer la distribución de frecuencia de los pólenes y caracterizar cada origen floral, según los pólenes acompañantes y los años de cosecha. Se analizaron 81 muestras de miel, de cuatro cosechas diferentes. Se encontraron 41 tipos morfológicos de polen, cuya variación por muestra osciló entre dos y ocho. El taxón presente en más del 80% de las mieles fue Eucalyptus sp. Los principales pólenes acompañantes encontrados pertenecieron a los tipos Helianthus annuus y Carduus sp., para ambos orígenes florales estudiados, y a la familia de las Brassicaceae, para las mieles de tréboles. Los años de cosecha estudiados mostraron diferentes espectros polínicos.

Metabolomics demonstrates divergent responses of two Eucalyptus species to water stress

Past studies of water stress in Eucalyptus spp. generally highlighted the role of fewer than five “important” metabolites, whereas recent metabolomic studies on other genera have shown tens of compounds are affected. There are currently no metabolite profiling data for responses of stress-tolerant species to water stress. We used GC–MS metabolite profiling to examine the response of leaf metabolites to a long (2 month) and severe (Ψpredawn < −2 MPa) water stress in two species of the perennial tree genus Eucalyptus (the mesic Eucalyptus pauciflora and the semi-arid Eucalyptus dumosa). Polar metabolites in leaves were analysed by GC–MS and inorganic ions by capillary electrophoresis. Pressure–volume curves and metabolite measurements showed that water stress led to more negative osmotic potential and increased total osmotically active solutes in leaves of both species. Water stress affected around 30–40% of measured metabolites in E. dumosa and 10–15% in E. pauciflora. There were many metabolites that were affected in E. dumosa but not E. pauciflora, and some that had opposite responses in the two species. For example, in E. dumosa there were increases in five acyclic sugar alcohols and four low-abundance carbohydrates that were unaffected by water stress in E. pauciflora. Re-watering increased osmotic potential and decreased total osmotically active solutes in E. pauciflora, whereas in E. dumosa re-watering led to further decreases in osmotic potential and increases in total osmotically active solutes. This experiment has added several extra dimensions to previous targeted analyses of water stress responses in Eucalyptus, and highlights that even species that are closely related (e.g. congeners) may respond differently to water stress and re-watering

Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region

The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids), coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

Carbohydrate and Amino Acid Metabolism in the Eucalyptus globulus-Pisolithus tinctorius Ectomycorrhiza during Glucose Utilization1

The metabolism of [1-13C]glucose in Pisolithus tinctorius cv Coker & Couch, in uninoculated seedlings of Eucalyptus globulus bicostata ex Maiden cv Kirkp., and in the E. globulus-P. tinctorius ectomycorrhiza was studied using nuclear magnetic resonance spectroscopy. In roots of uninoculated seedlings, the 13C label was mainly incorporated into sucrose and glutamine. The ratio (13C3 + 13C2)/13C4 of glutamine was approximately 1.0 during the time-course experiment, indicating equivalent contributions of phosphoenolpyruvate carboxylase and pyruvate dehydrogenase to the production of α-ketoglutarate used for synthesis of this amino acid. In free-living P. tinctorius, most of the 13C label was incorporated into mannitol, trehalose, glutamine, and alanine, whereas arabitol, erythritol, and glutamate were weakly labeled. Amino acid biosynthesis was an important sink of assimilated 13C (43%), and anaplerotic CO2 fixation contributed 42% of the C flux entering the Krebs cycle. In ectomycorrhizae, sucrose accumulation was decreased in the colonized roots compared with uninoculated control plants, whereas 13C incorporation into arabitol and erythritol was nearly 4-fold higher in the symbiotic mycelium than in the free-living fungus. It appears that fungal utilization of glucose in the symbiotic state is altered and oriented toward the synthesis of short-chain polyols.

Análise de metabólitos e proteínas totais em folhas de Eucalyptus grandis durante a infecção por Puccinia psidii

Os mecanismos moleculares envolvidos na resistência de plantas contra patógenos são um tema bastante discutido no meio acadêmico, sendo o objetivo maior dos estudos a diminuição das perdas de produtividade provocadas por doenças em plantações do mundo todo. Muitos modelos de interação patógeno-hospedeiro foram propostos e desenvolvidos priorizando plantas e culturas de rápido desenvolvimento com ciclo de vida curto. Espécies de ciclo longo, porém, devem lidar durante anos - ao menos até a idade reprodutiva - contra o ataque de bactérias, fungos e vírus, sem contar, nesse meio tempo, com recombinações genéticas e mutações que tornariam possível o escape contra as moléstias causadas por microrganismos. Assim, como alternativa aos modelos usuais, o presente trabalho estudou um diferente par de antagonistas: Eucalyptus grandis e Puccinia psidii. Apesar da contribuição de programas de melhoramento genético, o patossistema E. grandis X P. psidii ainda é pouco descrito no nível molecular, havendo poucos estudos sobre os processos e as moléculas que agem de forma a conferir resistência às plantas. Assim, buscando o melhor entendimento da relação entre E. grandis X P. psidii, o presente trabalho estudou a mudança dos perfis de proteínas e metabólitos secundários ocorrida nos tecidos foliares de plantas resistentes e susceptíveis durante a infecção pelo patógeno, com o auxílio da técnica de cromatografia líquida acoplada à espectrometria de massas. Os resultados obtidos indicam que as plantas resistentes percebem a presença do patógeno logo nas primeiras horas pós-infecção, produzindo proteínas ligadas à imunidade (HSP90, ILITYHIA, LRR Kinase, NB-ARC disease resistance protein). Essa percepção desencadeia a produção de proteínas de parede celular e de resposta oxidativa, além de modificar o metabolismo primário e secundário. As plantas susceptíveis, por outro lado, têm o metabolismo subvertido, produzindo proteínas responsáveis pelo afrouxamento da parede celular, beneficiando a absorção de nutrientes, crescimento e propagação de P. psidii. No trabalho também são propostos metabólitos biomarcadores de resistência, moléculas biomarcadoras de resposta imune e sinais da infecção por patógeno em E. grandis.

Methane dry reforming over Ni supported on pine sawdust activated carbon: Effects of support surface properties and metal loading

The influence of metal loading and support surface functional groups (SFG) on methane dry reforming (MDR) over Ni catalysts supported on pine-sawdust derived activated carbon were studied. Using pine sawdust as the catalyst support precursor, the smallest variety and lowest concentration of SFG led to best Ni dispersion and highest catalytic activity, which increased with Ni loading up to 3 Ni atoms nm-2. At higher Ni loading, the formation of large metal aggregates was observed, consistent with a lower "apparen" surface area and a decrease in catalytic activity. The H2/CO ratio rose with increasing reaction temperature, indicating that increasingly important side reactions were taking place in addition to MDR.

Fire protection precautions for handling uranium turnings, chips, borings, sawdust, and powder /

"4-10-50--825-A11578."

A critical revision of the genus Eucalyptus,

"Published by the authority of the Government of the State of New South Wales."