Screening for condensed tannin-degrading fungi with a synthetic <Superscript>14</Superscript>C-labeled compound

To find fungi that are potent for degradation of condensed tannin, a two-step screening was used. This involved measurement of fungal growth rate on Japanese cedar (Cryptomeria japonica) bark, followed by determination of [¹⁴C]-labeled CO₂ generated from fungal degradation of synthetic [¹⁴C]-labeled condensed tannin model. In the first screening, 75 strains of wood rot fungi were tested, and 19 strains effectively decreased bark weight and/or the weight of the methanol-soluble fraction. For the second screening, [¹⁴C]-labeled condensed tannin model compound was synthesized in 11.8% yield based on radioactivity measurements. Over the incubation period, Coriolus hirsutus K-2671, Lentinus edodes Is, and Lampteromyces japonicus Nn showed higher cumulative [¹⁴C]-labeled CO₂ emissions than the other strains and mineralized the [¹⁴C]-labeled condensed tannin model compound by 3.7%, 3.0%, and 3.0%, respectively. Fractionation of the methanol extracts from the medium by gel permeation chromatography after fungal treatment suggested that fungi that can induce the emission of significant levels of [¹⁴C]-labeled CO₂ can extensively depolymerize condensed tannins.     

黑荆树单宁与金属离子络合性质的研究

采用pH电位滴定法测定了不同温度下,离子强度(I)0.1 mol/L的NaCl溶液中单宁酸、橡椀单宁、黑荆树单宁的加质子常数和若干金属络合物稳定常数,考察了单宁结构单元对Fe3 、Cu2 、Zn2 、Ni2 的离子络合选择性的影响,讨论了影响加质子常数和稳定常数的因素。研究结果表明,实验温度下单宁对Fe3 、Cu2 的络合稳定常数大小为:黑荆树单宁>橡椀单宁>单宁酸,对Zn2 、Ni2 的络合稳定常数大小为:橡椀单宁>黑荆树单宁>单宁酸。升高温度有利于酚羟基的解离但不利于单宁-金属络合物的形成。用柱层析提纯的黑荆树单宁对其金属络合物的稳定常数的影响不大。     

Sorption of metal ions from aqueous solution to spruce bark

The concentrations and protonation constants of the functional groups like carboxyl and phenolic hydroxyl groups in spruce bark were determined by a potentiometric acid–base titration method. The non-cellulosic carbohydrates in spruce bark were also characterized by acid methanolysis and GC, including determination of the uronic acid units, which are the key units involved in metal sorption. Sorption of metal ions to bark takes place by ion exchange, mainly by complexation to these functional groups. The sorption equilibrium time, studied by using a batch method, was approximately 5 min. The metal sorption capacity of spruce bark and the affinity order of metal ions were studied with four different metal ion mixtures using a column chromatographic method. Because a method of competition was used, concentration of metal ions adsorbed to bark depends on the metal ions present in the mixtures studied. In the sorption experiments with same metal ion mixtures, inner bark of spruce exhibited higher sorption capacity than outer bark. By combination of the results from several experiments, the following affinity order was obtained Fe³⁺ ? Pb²⁺ ? Cu²⁺ ? Cd²⁺ > Zn²⁺ > Ni²⁺ > Ba²⁺ > Ca²⁺ > Sr²⁺ > Mn²⁺ > Mg²⁺ ? K⁺ ~ Na⁺ ~ Li⁺. Bark has a great potential as an effective and inexpensive sorbent for removal of metal ions from, e.g., waste water.     

Electrical migration of exogenous mineral ions through green sapwood ofPinus sylvestris L. (Scots pine)

Summary The electrical migration was studied of several cations passing longitudinally through cylindrical samples of green sapwood ofPinus sylvestris L. under the influence of an applied electric field. This led to values for the hindered ionic conductances within the wood of the cations Li⁺, K⁺ and CU²⁺ which were compared with data obtained previously (Simons et al., 1998) for several endogenous cations. There was satisfactory agreement for the conductance of the potassium ion, the only one to be determined by both methods. Copper ions were found to possess a higher conductance within the wood than calcium or magnesium, a factor relevant to its use as a wood preservative. Visual observation of the location of the blue-green colouration produced in the wood by copper ions indicated that they migrated via longitudinal resin ducts and tracheids. Elution and transport experiments were also carried out with sapwood which had been flushed with water, Li₂SO₄ or CuSO₄ solution.Symbols E potential gradient - F Faraday's constant (96, 494 C/mol) - I current - L length of wood sample - M molarity (mol/dm³) - Q quantity of electricity - R electrical resistance - S Siemens (reciprocal ohm) - t time - u ionic mobility (velocity under unit potential gradient) - v ionic velocity - z charge number of ion - ionic conductance The authors thank SERC and Rentokil PLC for the award of a CASE Research Studentship to P.J.S. and the Leverhulme Trust for the award of an Emeritus Fellowship to M.S.     

Determination of reaction rate parameters for the acid copper chromate fixation reactions on oak (Quercus castaneifolia C. A. Mey) sapwood

Acid copper chromate fixation reactions on oak (Quercus castaneifolia C. A. Mey) sapwood were characterized by at least two distinguished reaction periods which differ in their kinetic behavior, particularly reaction rate. In this research, chemical rate equation parameters were studied in detail as a function of chromium fixation time. Theoretically, the kinetic data were distinguished between the adsorption and reduction reactions and consequently, the rate parameters were determined for each stage distinctly. The obtained results showed that at the investigated thermal range (25–33°C), almost for every 3°C increase in temperature the reaction duration has decreased 20.4?min for the first reaction period and 78?min for the second reaction period. Besides that, in all sample replications, up to 58.3% of hydrogen ions function at the reduction reactions of the initial period, demonstrating that acidity (H⁺ ions) has a major effect on reaction rate constant. Accordingly, adsorption reactions of the hexavalent chromium at the starting point follow a pseudo-first-order kinetic reaction. Different to the adsorption reaction the Cr^VI reduction reaction is exothermic with a measured exothermal energy of 48.2?kJ/mol.     

Electrical transport of endogenous mineral ions in green sapwood ofPinus sylvestris L. (Scots pine)

Summary The relative migration of the major endogenous ions (K⁺, Ca²⁺ Mg²⁺, Na⁺, Cl^– in green sapwood ofPinus sylvestris L. was measured in a modified Hittorf transference cell. The transference numbers obtained gave the fractions of the current carried by these ions when an electric field was applied across the wood samples under the conditions used.Potassium and calcium ions were always found to be the main endogenous current carriers, followed by magnesium, sodium and chloride ions. No significant differences in transference number were found between wood stored under refrigeration or in a deep freeze, nor was there any effect on prior -irradiation. Fungal contamination in a few non-irradiated specimens led to lower transference numbers. Changes in moisture content from 86 to 141% produced no significant change but the results did depend on the tree from which the samples had been taken. A decrease in the length of the wood sample from 100 to 50 mm had little effect on the transference numbers of calcium ions but caused a decrease in those of potassium when larger quantities of electricity were passed. Transversely- and longitudinally-oriented wood samples, however, gave very similar results. Visual observation of the anode compartment indicated that the ions followed the path of least resistance between cathode and anode and that the current passed along the grain of the wood.Symbols c_i molar concentration of ion i - F Faraday's constant (96 494 C/mol) - I current - t time - t_i transference number of ion i (also shown as t(i) in tables) - V volume of electrode compartment - Z_i charge number of ion i The authors thank SERC and Rentokil PLC for the award of a CASE Research Studentship to P.J.S. and the Leverhulme Trust for the award of an Emeritus Fellowship to M.S.     

Condensed tannins in Leucaena and their relation to psyllid resistance

Leucaena species and hybrids were examined to determine the relative content of condensed tannins and its relationship to susceptibility to defoliation by the Leucaena psyllid (Heteropsylla cubana). The interspecific Leucaena hybrid KX2 (L. leucocephala × L. pallida) was examined for variability of condensed tannin levels. A broad range of condensed tannin values were found which indicate potential for improved forage value through selection for KX2 trees with lower condensed tannin while maintaining psyllid resistance. A significant correlation was not found linking condensed tannins and psyllid resistance.     

单宁-醛-胶原的反应——对植醛结合鞣机理的再认识

以黑荆树单宁为植物鞣剂，嗯唑烷为醛鞣剂，较系统地研究了氢键、疏水键、胶原氨基在植鞣、醛鞣和植-醛结合鞣中的作用。证实了植-醛结合鞣的反应机理与已有的认识有很大的区别。醛类化合物即使在植鞣后加入，其主要的反应基团仍然是皮胶原的氨基。但是当单宁分子中含有亲核活性较高的反应基团时，醛类化合物可以在皮胶原和单宁分子之间形成交联键。这种交联作用可以对提高皮胶原的热稳定性产生协同效应，而且使单宁与皮胶原的结合稳定性进一步加强，能够抵御氢键破坏试剂和疏水键破坏试剂的作用。采用缩合类单宁时，容易形成胶原-醛-单宁交联键；但采用水解类单宁时，形成这种交联键的几率很小。     

Investigation of a new natural particleboard adhesive composed of tannin and sucrose

In the face of dwindling fossil fuel resources and the environmental imperative to reduce emissions associated with petrochemistry, there is strong demand for a wood composite bonding procedure using natural alternatives. In this study, particleboards were manufactured with a new material adhesive composed of tannin and sucrose, and hot-pressed at 200 °C for 10 min, to a target density of 0.8 g/cm³. We found optimal values for the mat moisture content, the ratio of tannin to sucrose and the resin content of 3–6 wt%, 25/75 and 30–40 wt%, respectively. When the particleboards were manufactured under these optimum conditions, the modulus of rupture and the modulus of elasticity were in the range of 19.6–21.2 MPa and 4.6–5.0 GPa, respectively. The internal bond strength was in the range of 1.1–1.3 MPa. Based on these results, the mechanical properties of particleboard bonded with tannin and sucrose were higher than the requirements of the JIS A 5908 type 18 standard (2003). In the thickness swelling test (TS), the value was in the range of 20–23 %; as the ratio of sucrose and resin content increased, the TS value decreased. The reaction mechanism between tannin and sucrose was studied by fourier transform infrared spectroscopy, and the dimethylene ether bridges were observed. Consequently, it is possible that a tannin and sucrose mixture can be used as a natural adhesive for particleboard.     

Acoustic emission related to instantaneous strain in Tasmanian eucalypt timber during seasoning

Summary Acoustic Emission (AE) was measured in 30 mm-thick backsawn and quartersawn Tasmanian Oak (Eucalyptus regnans F. muell) boards drying at temperatures in the vicinity of 20 °C. By varying the diffusion coefficient used in a non-linear drying simulation program, calculated half-thickness moisture profiles were matched to measured profiles in a sample board. Once the measured and calculated drying behaviour was satisfactorily matched, the AE measured in an endmatched board closely followed the surface instantaneous strain calculated with the program. The AE activity increased once the surface instantaneous strain attained the proportional limit. The AE is not simply related to drying temperature or humidity but rather to a complex interaction between the two parameters.Symbols c_a Moisture concentration in air (kg/m³) - c_s Moisture concentration at the board surface (kg/m³) - D Diffusion coefficient (m²/hr) - DBT Dry bulb temperature (°C) - e_i Instantaneous strain - RH Relative humidity (%) - WBT Wet bulb temperature (°C) - Basic density (kg/m³) The author is pleased to acknowledge the assistance of Emeritus Professor A. R. Oliver, Associate Professor P. E. Doe, University of Tasmania, the Australian Furniture Research and Development Institute and the Tasmanian Timber Promotion Board     

STUDIES ON STEPWISE STABILITY CONSTANTS OF COORDINATION COMPOUNDS FROM SULFONATED SHEOAK TANNIN WITH METAL IONS

The stepwise stability constants of coordination compounds from sulfonatedsheoak tannin with metal ions have been determined by pH potential method with catechol asmodel compounds at 20℃and constant ionic strength.     

Utilization of browse supplements with varying tannin levels by Ethiopian Menz sheep: 1. Intake, digestibility and live weight changes

The effect of tannins in browse supplements on intake, digestibility and live weight changes was evaluated using sixty-six male Ethiopian Menz sheep in a 90-day trial. Teff straw (Eragrostis tef) was fed ad libitum (control diet), or supplemented with 190 g dried leaves of six Sesbania sesban accessions with increasing levels of condensed tannin (S1, S2, S3, S4, S5 and S6), lablab (Dolichos lablab), tagasaste (Chamaecytisus palmensis), leucaena (Leucaena leucocephala) and goetzei (Sesbania goetzei), in a completely randomized block design. The condensed tannins were highest in goetzei, S6, S5 and leucaena, intermediate in S4, S3, S2 and S1, and lowest in tagasaste and lablab. The forages differed significantly (P < 0.05) in their rates of degradation and truly undegradable dry matter. Lablab had lower water solubility and higher (P < 0.05) truly undegradable dry matter than the other browse supplements. With increasing tannin levels among Sesbania accessions, there was a significant decrease (P < 0.05) in the rate of degradation. Animals supplemented with forage legumes with low condensed tannin levels such as lablab, S1, S2, and S3 had a lower teff straw intake than those on the control diet. The converse was true for those fed with the high tannin supplements such as S4, S5, S6 and goetzei. Supplementation significantly (P < 0.05) increased total dry matter intake and live weight gains (LWG). The animals on the control diet lost weight (–1.9 g/kgW^0.75, while the supplemented animals gained between 2.9 and 4.4 g/kgW^0.75 daily. Leucaena supplementation promoted higher (P < 0.05) LWG than lablab, S1 and goetzei. With increasing tannin levels among Sesbania accessions, there was an increase (S1 < S2 < S3 < S4) followed by a decrease (S6 > S5 > goetzei) in LWG. The digestibilities of total DM and the supplements did not differ significantly (P < 0.05) between the diets, although the neutral detergent fibre (NDF) digestibility decreased significantly (P < 0.05) with supplementation. The control diet had significantly higher NDF digestibility than the leucaena, S3, S4, S5 and S6 supplemented diets. Results have beneficial attributes at low levels in ruminants. Condensed tannins confer important advantages in ruminant nutrition with respect to the prevention of excessive degradation of protein in the rumen. This revised version was published online in June 2006 with corrections to the Cover Date.     

Opportunities for domesticating the African baobab (Adansonia digitata L.): multi-trait fruit selection

Among the priority species identified for domestication in the Sahel region of Sub-Sahara Africa is the baobab (Adansonia digitata L.) tree. The quantification of the variation in nutrient content and fruit morphological traits of trees is one of the most important steps in identifying superior planting material for domestication. Ten provenances in Mali covering all the different agro-ecological zones were selected and the fruit morphological traits, vitamin C, calcium, iron and colour were studied. Mean pulp content was 2,149 ± 1,117 , 2,406 ± 776  and 25 ± 17 mg kg^?1 for vitamin C, calcium and iron, respectively. Fruit pulp colour varied from white, creamy to pink and a significant correlation between pulp vitamin C content and reflectance in the green and blue bands was observed. Significant negative correlations were found between rainfall and pulp vitamin C content and between mean annual temperature and fruit and pulp weight and pulp fraction, suggesting that these traits are influenced by the environment. Pulp iron content correlated positively with topsoil sodicity and base saturation. Similarly, pulp vitamin C content correlated positively with topsoil sand fraction. Pulp reflectance in the blue and green bands correlated negatively with topsoil pH water and base saturation, respectively. The variation in nutritive and morphological traits offers the opportunity for selecting plus trees with a combination of desired traits for domestication.     

Cesium adsorption from aqueous solutions onto Japanese oak charcoal III: effects of water-extraction treatment

To remove group 1 and 2 metal ions from Japanese oak (Quercus serrata Thunb. and/or Quercus crispula Blume) charcoal (OC), a water-extraction treatment was employed. The treatment was repeated 1, 4, 8, or 12 times. The amounts of four metal (sodium, potassium, magnesium, and calcium) ions eluted from non-treated and treated OC were determined using an ion chromatographic apparatus. The effects of water-extraction treatment on the ability of OC to adsorb cesium were investigated using 2.50 × 10^?5 and 2.50 × 10^?6 mol/L aqueous cesium chloride solutions. As for both aqueous solutions, an unexpected result was obtained in that the cesium-adsorption ability of OC decreased suddenly when the repetition of water-extraction treatments exceeded a certain threshold. We explain the results in terms of pH of the sample solutions and the point of zero charge for OC.     

Effect of pre-feeding forage treatments,harvesting stage,and animal type on preference of tagasaste (<Emphasis Type="Italic">Chamaecytisus palmensis</Emphasis>)

Tagasaste (Chamaecytisus palmensis), a multipurpose fodder tree, is highly productive in the tropical highlands. The forage has high crude protein (CP) concentrations but is reported to have low intake by ruminants. This study investigated the effects of plant harvest stage and feeding management (wilted, dried and fresh) on levels of tannins in tagasaste and on preference and intake by Menz sheep and cattle fed during the dry season. The treatments were (1) fresh tagasaste, (2) wilted tagasaste, (3) dried tagasaste and (4) native hay. There were three preference experiments using sheep (20.2 ± 0.66 kg) to investigate intake under ad libitum or restricted offering of the forages, and to assess effect of harvest age (6- or 10-month regrowth age) on ad libitum intake. In two further experiments ad libitum offerings of the forages were evaluated using young steers (131.2 ± 19.6 kg) and heifers (156.3 ± 5.4 kg). The CP (201 g/kg), hydrolysable tannin (150.2 g/kg) and condensed tannin (8.97abs measured as absorbance at 550 nm wavelength/g NDF) contents of tagasaste forage were not affected by the physical treatments and harvesting stage. When fed ad libitum, sheep preferred (P < 0.01) fresh forage to wilted or dry tagasaste (24.5 vs. 22.9 and 7.9 g dry matter (DM)/kg metabolic body weight (MBW). The restricted offering increased intake of the less preferred dried form. Regrowth age (6 vs. 10 months) did not affect sheep preference. Unlike sheep, steers and heifers preferred (P < 0.01) dried tagasaste rather than the fresh or wilted forage. Animal preference and intake were affected by the preparation method of the forage, but not by regrowth age. Methods to improve intake (for cattle), effects of long-term feeding and evaluation on the subsequent effect of anti-nutritional compounds during digestion and animal performance should be further investigated.     

Structural elucidation of condensed tannin from the bark waste of <Emphasis Type="Italic">Acacia crassicarpa</Emphasis> plantation wood in Indonesia

Recently, Acacia crassicarpa has been planted in peatland areas with acidic soil in Indonesia for use in pulp and paper materials. Its bark is not suitable to produce bleached pulp; hence, it is discarded as waste. Meanwhile, in South Africa and other countries, Acacia mearnsii has been planted for a long time, and its bark extracts have been used as a leather tanning agent. First, the structure of condensed tannin from the bark waste of A. crassicarpa is characterized. The yield of the extracts obtained from A. crassicarpa using a 70% acetone aqueous solution (7% based on bark weight) is less than that obtained from A. mearnsii (34%). A novel flavan dimer from the condensed tannin, specific to A. crassicarpa, is isolated from the bark extracts. To the best of our knowledge, this dimer is a new compound as evidenced from pyrolysis–gas chromatography–mass spectrometry and nuclear magnetic resonance analyses; it corresponds to a gallocatechin–catechin flavan dimer with the absence of one oxygen atom at the 3C of the pyran ring. In addition, 2,4,6-trimethoxybenzoic acid methyl ester is identified as a novel pyrolysis product obtained from the cleavage of the pyran ring.     

Adsorption of metal and uranyl ions onto amidoximated Pinus densiflora bark

Pine (Pinus densiflora) bark was chemically modified by grafting with acrylonitrile (AN) through Fenton reaction and conversion of the cyano group to an amidoxime group by reaction with hydroxylamine. Treatments of pine bark with 160 mM H₂O₂ at 40°C yielded ~70% grafting in 6-h reaction. After alkali hydrolysis of amidoximated pine bark (AOPB), its adsorption capacity (q _e) for copper ions was largely increased from 0.5 to 1.8 mmol/g. Adsorption of the hydrolyzed AOPB (HAOPB) followed the pseudo-second-order kinetic model. Among the metal ions tested, the order of adsorption capacity (q _e) predicted by the kinetic model at equilibrium time was Hg²⁺ > UO₂ ²⁺ > Cd²⁺ > Cu²⁺ > Zn²⁺ > Ni²⁺. The adsorption process was pH-dependent, and the adsorption equilibrium was observed in the pH range of 6–7 for all the metal ions. Even though pine bark is a good adsorbent for Hg²⁺ and UO₂ ²⁺ ions, it had a poor affinity for the other ions tested. It was obviously found that HAOPB had very high adsorption abilities for heavy metal and uranyl ions.     

云南栽培玛咖的营养成分分析与评价

对云南栽培的玛咖营养成分进行了分析,并与文献报道的秘鲁产玛咖进行了比较.结果表明:云南栽培玛咖含有16.7×104mg·kg-1的蛋白质、21.5×104·mg·kg-1粗纤维、9.30%氨基酸、多种无机元素、多种维生素等营养成分,脂肪含量低;所含营养成分的种类与秘鲁产玛咖类似,其中对人体有益的蛋白质、粗纤维、钙、铁、锌、VC等成分的含量较高,表明云南栽培玛咖的营养丰富,具有开发利用价值.