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PubMed2006

Clonal propagation of softwoods.

Softwoods or gymnosperms, which make up 60% of the forested areas of the world, are economically important as a source of lumber, pulp, and paper. Reforestation is a major activity worldwide and the potential benefits of using clonal planting stock have long been recognized. Tissue culture clonal methods or micropropagation is a newer approach that can be achieved by enhancing axillary bud breaking, production of adventitious buds (organogenesis), and somatic embryogenesis. Plantlet production via organogenesis requires at least four stages: (1) bud induction on the explant, (2) shoot development and multiplication, (3) rooting of developed shoots, and (4) hardening of plantlets. Similarly, the production of plantlets via somatic embryogenesis, which has the potential to produce a larger number of plantlets, and in a shorter period of time, also requires several stages. These include (1) induction, maintenance, and proliferation of embryogenic tissue; (2) maturation (both morphological and physiological) of somatic embryos; and (3) germination and conversion of the somatic embryos. In this chapter, plantlet production via organogenesis from seedling and adolescent/mature explants and somatic embryogenesis from immature and mature seeds of white spruce (Picea glauca) are outlined.

Culture Media↗
PubMed2002

A model explaining declining rate in hydrolysis of lignocellulose substrates with cellobiohydrolase I (cel7A) and endoglucanase I (cel7B) of Trichoderma reesei.

It is commonly observed that the rate of enzymatic hydrolysis of solid cellulose substrates declines markedly with time. In this work the mechanism behind the rate reduction was investigated using two dominant cellulases of Trichoderma reesei: exoglucanase Cel7A (formerly known as CBHI) and endoglucanase Cel7B (formerly EGI). Hydrolysis of steam-pretreated spruce (SPS) was performed with Cel7A and Cel7B alone, and in reconstituted mixtures. Throughout the 48-h hydrolysis, soluble products, hydrolysis rates, and enzyme adsorption to the substrate were measured. The hydrolysis rate for both enzymes decreases rapidly with hydrolysis time. Both enzymes adsorbed rapidly to the substrate during hydrolysis. Cel7A and Cel7B cooperate synergistically, and synergism was approximately constant during the SPS hydrolysis. Thermal instability of the enzymes and product inhibition was not the main cause of reduced hydrolysis rates. Adding fresh substrate to substrate previously hydrolyzed for 24 h with Cel7A slightly increased the hydrolysis of SPS; however, the rate increased even more by adding fresh Cel7A. This suggests that enzymes become inactivated while adsorbed to the substrate and that unproductive binding is the main cause of hydrolysis rate reduction. The strongest increase in hydrolysis rate was achieved by adding Cel7B. An improved model is proposed that extends the standard endo-exo synergy model and explains the rapid decrease in hydrolysis rate. It appears that the processive action of Cel7A becomes hindered by obstacles in the lignocellulose substrate. Obstacles created by disordered cellulose chains can be removed by the endo activity of Cel7B, which explains some of the observed synergism between Cel7A and Cel7B. The improved model is supported by adsorption studies during hydrolysis.

Adsorption↗
PubMed2000

Simultaneous saccharification and cofermentation of peracetic acid-pretreated biomass.

Previous work in our laboratories has demonstrated the effectiveness of peracetic acid for improving enzymatic digestibility of lignocellulosic materials. The use of dilute alkali solutions as a pre-pretreatment prior to peracetic acid lignin oxidation increased carbohydrate hydrolysis yields in a synergistic as opposed to additive manner. Deacetylation of xylan is easily achieved using dilute alkali solutions under mild conditions. In this article, we evaluate the effectiveness of peracetic acid combined with an alkaline pre-pretreatment through simultaneous saccharification and cofermentation (SSCF) of pretreated hybrid poplar wood and sugar cane bagasse. Respective ethanol yields of 92.8 and 91.9% of theoretical are achieved using 6% NaOH/15% peracetic acid-pretreated substrates and recombinant Zymomonas mobilis CP4/pZB5. Reduction of acetyl groups of the lignocellulosic materials is demonstrated following alkaline pre-pretreatments. Such processing may be helpful in reducing peracetic acid requirements. The influence of deacetylation is more significant in combined pretreatments using lower peracetic acid loadings.

Biomass↗
PubMed2000

Two-stage dilute-acid pretreatment of softwoods.

Whole tree chips obtained from softwood forest thinnings were pretreated via single- and two-stage dilute-sulfuric acid pretreatment. Whole-tree chips were impregnated with dilute sulfuric acid and steam treated in a 4-L steam explosion reactor. In single-stage pretreatment, wood chips were treated using a wide range of severity. In two-stage pretreatment, the first stage was carried out at low severity to maximize hemicellulose recovery. Solubilized sugars were recovered from the first-stage prehydrolysate by washing with water. In the second stage, water-insoluble solids from first-stage prehydrolysate were impregnated with dilute sulfuric acid, then steam treated at more severe conditions to hydrolyze a portion of the remaining cellulose to glucose and to improve the enzyme digestibility. The total sugar yields obtained after enzymatic hydrolysis of two-stage dilute acid-pretreated samples were compared with sugar yields from single-stage pretreatment. The overall sugar yield from two-stage dilute-acid pretreatment was approx 10% higher, and the net enzyme requirement was reduced by about 50%. Simultaneous saccharification and fermentation using an adapted Saccharomyces cerevisiae yeast strain further improved cellulose conversion yield and lowered the enzyme requirement.

Cellulase↗
PubMed2000

Cellulase production of Trichoderma reesei Rut C 30 using steam-pretreated spruce. Hydrolytic potential of cellulases on different substrates.

Various techniques are available for the conversion of lignocellulosics to fuel ethanol. During the last decade processes based on enzymatic hydrolysis of cellulose have been investigated more extensively, showing good yield on both hardwood and softwood. The cellulase production of a filamentous fungi, Trichoderma reesei Rut C 30, was examined on carbon sources obtained after steam pretreatment of spruce. These materials were washed fibrous steam-pretreated spruce (SPS), and hemicellulose hydrolysate. The hemicellulose hydrolysate contained, besides water-soluble carbohydrates, lignin and sugar degradation products, which were formed during the pretreatment and proved to be inhibitory to microorganisms. Experiments were performed in a 4-L laboratory fermentor. The hydrolytic capacity of the produced enzyme solutions was compared with two commercially available enzyme preparations, Celluclast and Iogen Cellulase, on SPS, washed SPS, and Solka Floc cellulose powder. There was no significant difference among the different enzymes produced by T. reesei Rut C 30. However, the conversion of cellulose using these enzymes was higher than that obtained with Iogen or Celluclast cellulases using steam-pretreated spruce as substrate.

Cellobiose↗
PubMed2000

Simultaneous saccharification and fermentation of steam-pretreated spruce to ethanol.

Ethanol production was studied in simultaneous saccharification and fermentation (SSF) of steam-pretreated spruce at 42 degrees C, using a thermotolerant yeast. Three yeast strains of Kluyveromyces marxianus were compared in test fermentations. SSF experiments were performed with the best of these on 5% (w/w) of substrate, at a cellulase loading of 37 filter paper units/g of cellulose, and a beta-glucosidase loading of 38 IU/g of cellulose. The detoxification of the substrate and the lack of pH control in the experiments increased the final ethanol concentration. The final ethanol yield was 15% lower compared to SSF with Saccharomyces cerevisiae at 37 degrees C, owing to the cessation of ethanol fermentation after the first 10 h.

Cellulase↗
PubMed2000

Steam pretreatment of Douglas-fir wood chips. Can conditions for optimum hemicellulose recovery still provide adequate access for efficient enzymatic hydrolysis?

Douglas-fir sapwood and heartwood were impregnated with SO2 and steam exploded at three severity levels, and the cellulose-rich, water-insoluble component was enzymatically hydrolyzed. The high-severity conditions resulted in near complete solubilization and some degradation of hemicelluloses and a significant improvement in the efficiency of enzymatic digestibility of the cellulose component. At lower severity, some of the hemicellulose remained unhydrolyzed, and the cellulose present in the pretreated solids was not readily hydrolyzed. The medium-severity pretreatment conditions proved to be a good compromise because they improved the enzymatic hydrolyzability of the solids and resulted in the recovery of the majority of hemicellulose in a monomeric form within the water-soluble stream. Sapwood-derived wood chips exhibited a higher susceptibility to both pretreatment and hydrolysis and, on steam explosion, formed smaller particles as compared to heartwood-derived wood chips.

Cellulase↗
PubMed2000

Effect of chip size on steam explosion pretreatment of softwood.

Although considerable progress has been made in technology for converting lignocellulosic biomass into ethanol, substantial opportunities still exist to reduce production costs. In biomass pretreatment, reducing milling power is a technological improvement that will substantially lower production costs for ethanol. Improving sugar yield from hemicellulose hydrolysis would also reduce ethanol production costs. Thus, it would be desirable to test innovative pretreatment conditions to improve the economics by reducing electrical power of the milling stage and by optimizing pretreatment recovery of hemicellulose, as well as to enhance cellulose hydrolysis. The objective of this study was to evaluate the effect of chip size (2-5, 5-8, and 8-12 mm) on steam-explosion pretreatment (190 and 210 degrees C, 4 and 8 min) of softwood (Pinus pinaster).

Biomass↗
PubMed1997

Biotransformation of the fungal toxin fomannoxin by conifer cell cultures.

Fomannoxin [(+/-)-5-Formyl-2-isopropenyl-2,3-dihydrobenzofurane] is a phytotoxic secondary metabolite, which is produced by the forest pathogenic basidiomycete Heterobasidion annosum during the infection process. Fomannoxin shows growth-inhibiting effects on callus and suspension cultures of conifer cells. By investigating the interaction of the phytotoxin with Pinus sylvestris cells a detoxification of fomannoxin was detected, presumably as a defense reaction of the plant cells. Undifferentiated green cell lines of Pinus sylvestris were used as target cells. To provide rac-fomannoxin as a substrate a simple method for the chemical synthesis was developed. It was found that the aromatic aldehyde group is reduced by the plant cells producing the non-toxic fomannoxin alcohol which was isolated and identified by spectroscopy. After longer incubation times, also fomannoxin acid-beta-glucoside could be isolated as another detoxification metabolite. For comparison this glucoside was also synthesized.

Antifungal Agents↗
PubMedDate not supplied

Propolis from the Mediterranean region: chemical composition and antimicrobial activity.

The chemical composition of propolis from Bulgaria, Turkey, Greece and Algeria was investigated by GC-MS. All of them contained mainly flavonoids and esters of caffeic and ferulic acids, which indicated that their main source are buds of poplars of the taxonomic section Aegieros. Some Turkish samples contained a low percent of diterpenic acids, while in Algerian samples significant amounts of a hydroxyditerpenic acid (M=322, its structure not determined by its MS) were found. All samples showed significant antibacterial and weak to moderate antifungal activity.

Algeria↗
PubMedDate not supplied

A novel acetylated 3-deoxyanthocyanidin laminaribioside from the fern Blechnum novae-zelandiae.

The major 3-deoxyanthocyanin isolated from the fern Blechnum novae-zelandiae was determined to be luteolinidin 5-O-beta-D-[3-O-beta-D-glucopyranosyl-2-O-acetylglucopyranoside] and was found to co-occur with quercetin 3-O-beta-D-[6-O-caffeoylglucopyranoside], quercetin 3-O-beta-D-[6-O-caffeoylgalactopyranoside] and kaempferol 3-O-beta-D-glucuronopyranoside. These pigments were identified by using HPLC chromatography, NMR (1D, 2D) and electrospray mass spectroscopy.

Anthocyanins↗
PubMedDate not supplied

Antifeedants against Acusta despesta from the Japanese cedar, Cryptomeria japonica.

During our studies on the components in Japanese cedar, Cryptomeria japonica, we found that the crude methanol extract of C. japonica showed intense antifeeding activity against one snail species, Acusta despesta, which is well-known as a pest of many vegetables and crops. The active components in the extract were separated into the hexane and ethyl acetate soluble fractions. From the active ethyl acetate soluble fraction, two norlignans, sequirin-C and agatharesinol, were isolated and identified as the active compounds. Both compounds inhibited feeding behavior of A. despesta at 30 microg/cm2 and 40 microg/cm2 concentrations, respectively, when applied by an eggplant leaf or filter paper containing 20 microl of 5% sucrose solution.

Animals↗
PubMedDate not supplied

Nuclei of plants as a sink for flavanols.

Onion cepa (L.) and Tsuga canadensis (L.) Carr. were investigated histochemically on the association of flavanols to nuclei. The young roots of Onion cepa are totally devoid of flavanol structures. Therefore, the excised roots tips were directly incubated into different solutions of flavanols. After 3 h of incubation a flavanol binding on the nuclei was recognizable, as seen by a yellowish-brown tanning reaction. Still to ensure the presence of flavanols on the nuclei, subsequent staining with the p-dimethylaminocinnamaldehyde reagent (DMACA) resulted in an intense blue colouration. Tsuga canadensis has significant amounts of vacuolar flavanol deposits in all parts of the tree as indicated by the DMACA reagent. It is obvious that also the nuclei were associated strongly with flavanols which can be demonstrated particularly elegant in the cells of the seed wings by histochemical methods. However, the mode of flavanol release from the original deposits is not yet clear.

Cell Nucleus↗
PubMedDate not supplied

The repellence of Aristolochia aff. orbicularis roots against the corn borer Sitophilus zeamais.

The repellence of Aristolochia aff. orbicularis root, a native of Xochipala, Guerrero, Mexico, to the corn borer Sitophilus zeamais (Coleoptera) was investigated. The essential oil was isolated from the aromatic root and its repellent effect was assessed. About 40 components of the oil were identified using gas chromatography-mass spectrometry and other spectroscopic methods. The repellence of the roots, the oil and the chromatography fractions were also evaluated. Some fractions had a higher repellence than the total oil.

Animals↗
PubMedDate not supplied

Biochemical parameters as biomarkers for the early recognition of environmental pollution on Scots pine trees. II. The antioxidative metabolites ascorbic acid, glutathione, alpha-tocopherol and the enzymes superoxide dismutase and glutathione reductase.

Field investigations with Scots pine trees (Pinus sylvestris L.) were performed in eastern Germany, where ambient SO2, NOx and O3 concentrations differed significantly in 1992-99 at three sites, namely Neuglobsow (yearly mean SO2 in 1992: 9 microg m(-3)), Taura (yearly mean SO2 in 1992: 54 microg m(-3)) and Rösa (yearly mean SO2 in 1992: 73 microg m(-3)). To investigate the effects of SO2, NOx and O3 on antioxidants (superoxide dismutase, ascorbic acid, glutathione, glutathione reductase, alpha-tocopherol) and pigments including chlorophyll fluorescence as well as visible damage symptoms in the form of needle yellowing and tip necroses, needles of the 1st and 2nd age class from young and mature trees were collected at the sites every October. Eight years after the start of the field study in 1992, the ambient SO2 concentrations had decreased significantly at Neuglobsow (yearly mean SO2 in 1999: 4 microg m(-3)), Taura (yearly mean SO2 in 1999: 5 microg m(-3)) and Rösa (yearly mean SO2 in 1999: 5 microg m(-3)). NOx and O3 differed less at the three sites and showed no temporal variations. Whole needle glutathione continuously decreased, although concentrations were higher in needles of the 1st and 2nd age class from the polluted sites Taura and Rösa than the unpolluted site Neuglobsow. The activities of glutathione reductase exhibited the same site-related differences and temporal variations and were correlated with concentrations of oxidized glutathione (GSSG). In contrast, the activities of the enzyme superoxide dismutase and the concentrations of whole needle ascorbic acid remained unchanged over the period. Only at the end of the investigation period did the concentrations of oxidized ascorbic acid (dehydroascorbate) increase in six-month-old needles at the polluted sites Taura and Rösa. Despite the clear decreases in SO2, the visible symptoms of needle tip necroses remained unchanged, especially at the polluted sites Taura and Rösa, although the needles contained higher pigment concentrations than needles from the unpolluted sites. The results of measurements with antioxidants as biomarkers for SO2-mediated stress in pine needles show that the adult Scots pine trees at the polluted sites suffered from greater oxidative stress than the needles from the less polluted site.

Ascorbic Acid↗
PubMedDate not supplied

Chemical constituents from the infusion of Zollernia ilicifolia Vog. and comparison with Maytenus species.

The new flavonoid glycoside kaempferol-3-O-alpha-L-rhamnopyranosyl(1-->2)-O-[alpha-L-rhamnopyranosyl(1-->6)]-O-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside was isolated together with (S)-zierin from the leaves of Zollernia ilicifolia (Fabaceae), a medicinal plant used as analgesic and antiulcerogenic effects in Brazilian Tropical Atlantic Rain Forest. The structures were established on the basis of 1H, 13C NMR and 2D NMR (COSY, HMBC, HMQC), UV, MS and IV spectra. The infusion of Zollernia ilicifolia was qualitatively compared to the infusion of the espinheiras-santas (Maytenus aquifolium and Maytenus ilicifolia) by HPLC-DAD.

Brazil↗
PubMed2001

A 400-year tree-ring chronology from the tropical treeline of North America.

High-elevation sites in the tropics may be particularly sensitive to rapid climate change. By sampling treeline populations, I have developed the first extensive (> 300 years) tree-ring chronology in tropical North America. The site is Nevado de Colima, at the western end of the Mexican Neovolcanic Belt, and the species studied is Mexican mountain pine (Pinus hartwegii). Despite past logging in the area, 300 to 500-year old pines were found at 3600-3700 m elevation, about 300 m below the present treeline. The Nevado de Colima tree-ring chronology is well replicated from 1600 to 1997. Calibration with Colima climatic records points to summer monsoon precipitation as the strongest dendroclimatic signal. Most trees also exhibit extremely low growth in 1913 and 1914, following the January 1913 Plinian eruption of the Volcan de Colima. Because P. hartwegii is found on top of high mountains from Mexico to Guatemala, there is potential for developing a network of tropical treeline chronologies.

Cycadopsida↗