Characterization and application of recombinant β-glucosidase (BglH) from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> KCTC 1918

β-Glucosidase (β-1,4-D-glucoside glucohydrolase: EC.3.2.1.21) catalyzes the hydrolysis of β-glucosidic bonds between saccharides and aryl or alkyl groups. A gene encoding β-glucosidase from Bacillus licheniformis KCTC 1918, an anaerobic spore-forming soil bacterium, was cloned and characterized. The structural gene for the β-glucosidase consists of 1410 bp encoding 469 amino acid residues, and has a molecular weight of 53.4 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis with 12% separating gel. The enzyme activity was determined against pNPG as a substrate. The enzyme was optimally active at pH 6.0 (citrate-phosphate buffer) and 47°C. β-Glucosidase retained 100% of its original activity for 24 h. The activity of the enzyme was stimulated by glycerol and urea and was decreased by Ca²⁺, Cu²⁺, Hg²⁺, Mg²⁺, and Mn²⁺. In particular, Cu²⁺ had the strongest negative effect on β-glucosidase activity. The purified β-glucosidase was active against pNPG and cellobiose. When the β-glucosidase was tested for cellulose hydrolysis, the supplement of β-glucosidase with cellulose increased the glucose yield from pine wood powder by 139.8%.     

孟加拉无机肥料对几种农林作物生物固氮和种苗生长的影响(英文)

比较了不同浓度无机肥料(尿素和重过磷酸钙)对四种农林作物(楹树、雨豆树、相思树和印度田菁)生物固氮和种苗生长的影响。种子萌发一个月后利用不同浓度肥料(尿素:40kg·hm-2,80kg·hm-2;重过磷酸钙:40kg·hm-2,80kg·hm-2;(尿素 重过磷酸钙)40kg·hm-2和(尿素 重过磷酸钙)80kg·hm-2)处理种苗。结果表明:中等浓度无机肥料促进了种苗的生长,但较高浓度无机肥料也不利于种苗的生长。当施加尿素时根瘤菌的数量大小明显受抑制,但随着增加磷肥(重过磷酸钙)根瘤菌的数量大小增加。本研究有助于农业人员利用无机肥料改善土壤提高农林作物的生物固氮和种苗生长。图2表6参33。     

Relationship between species richness and biomass on environmental gradient in natural forest communities on Mt. Xiaolongshan,northwest China

We analyzed the relationship between species richness and biomass in natural forest communities at two similar sites on Mt. Xiaolongshan, northwest China. At both sites, a wide range of tree layer biomass levels was available by local biomass estimation models. In order to identify underlying mechanism of the species richness-biomass relationship, we included different water resource levels and number of individuals in each plot in our analysis. We sampled 15 and 20 plots （20 m ×20 m）, respectively, at both two sites. These plots were sampled equally on the sunny slope and the shady slope. Species richness, number of individuals of each species and diameter at breast height （DBH） as a substitute of biomass of tree layer were recorded in each sample. At one site, the relationship between species richness and biomass was significant on the sunny slope, and this relationship disappeared on the shady slope due to more environmental factors. The relations between species richness and number of individuals and between number of individuals and biomass paralleled the species richness-biomass relation on both slopes. The difference in number of individuals-biomass relationships on the sunny slope and the shady slope revealed ＂interspecific competitive exclusion＂ even though the species richness-biomass relationships were not hump-shaped. At the other site, species richness was not related to biomass or to number of individuals. Our study demonstrated the importance of environmental stress and succession of community in the understanding of species diversity-productivity patterns.     

Ecological and economical significance of homestead forest to the household of the offshore island in Bangladesh

An explanatory survey was conducted to assess the contribution of plant diversity to the ecological and socio-economic condition of the rural household in the offshore island of Bangladesh.Assessment was done by means of multistage random sampling.The homestead sizes of the study area were classified into 3 groups viz,large (>0.25 ha),medium (0.05-0.25 ha) and small (<0.05 ha) based on the result obtained from a preliminary survey,and a total of 45 homesteads,15 from each group,were selected randomly for the study.The average annual income from homestead's plant diversity varied from Tk 5730.00 (US$95.5) to Tk 17500.00 (US$291.67).The rural people were mainly dependent on their homegarden for woodfuel and nutritional requirement as forest was unavailable in the island.The rural people here also cultivated the plant species as a safety measure from frequent cyclone.Constraints hindering the development of homestead plantation were identified and suggestions were given such as the adequate supply of seedlings of fast growing native species and conservation of endangered species to meet the demand of the household as well as to keep ecological balance.     

Effect of components of leaching medium on the leaching of benzalkonium chloride from treated wood

Different leaching media composed of watersoluble extracts from Sakhalin fi r, Japanese cedar, and Japanese larch heartwoods and of taxifolin were used to characterize leaching of the C12 and C14 homologues of benzalkonium chloride from treated wood. The leaching medium of Sakhalin fi r extract moderately accelerated the leaching rates of the two homologues. Japanese cedar extract accelerated the leaching of the C12 homologue at a similar rate and that of the C14 homologue at a higher rate. Japanese larch extract remarkably accelerated the leaching rates of both homologues, particularly that of the C14 homologue. Thus, the leaching rate of the C14 homologue was higher than that of the C12 homologue with the Japanese cedar and larch extracts. The media of taxifolin, a major phenolic extractive of Japanese larch, preferentially accelerated the leaching rate of the C14 homologue. The amounts of phenolic compounds in the different leaching media were in the following order: Japanese larch > Japanese cedar > Sakhalin fi r. These results indicate a relationship between the amount of phenolic compounds and the leaching rates of the two homologues.     

Effects of contact with wood on blood pressure and subjective evaluation

This study examined the effects of contact with wood on the living human body using a physiological index and subjective evaluation. Consecutive blood pressure measurements were used as the physiological index, and sensory evaluation using the semantic differential (SD) method was used for subjective evaluation. Consideration was also given to cases in which materials were cooled and heated as well as kept at room temperature, to eliminate the effects of heat flux due to differences in thermal conductivity between wood and other materials. It was found that contact with wood produced coarse/natural sensations, with no associated increase in systolic blood pressure. Contact with cold wood created subjectively dangerous/uncomfortable but still coarse/natural sensations, also with no associated increase in blood pressure; therefore, there was no correspondence between subjective evaluation and physiological responses. Contact with aluminum kept at room temperature and cold acrylic plastic created flat/artificial and dangerous/uncomfortable sensations, with an associated significant increase in blood pressure; thus, there was a close correlation between subjective evaluation and physiological responses. It was therefore concluded that contact with wood, unlike artificial materials such as aluminum, induces no physiological stress even when kept at room temperature or cooled. Part of this report was presented at the 48th Annual Meeting of the Japan Wood Research Society in Shizuoka, April 1998     

Heartwood extractives from the Amazonian trees <Emphasis Type="Italic">Dipteryx odorata,Hymenaea courbaril</Emphasis>, and <Emphasis Type="Italic">Astronium lecointei</Emphasis> and their antioxidant activities

Heartwood extracts from Amazonian trees cumaru-ferro (Dipteryx odorata), jatoba (Hymenaea courbaril), and guarita (Astronium lecointei) exhibit antioxidant activities comparable with that of α-tocopherol, a well-known antioxidant. This article reports the characterization of the antioxidant compounds in the extracts of the three heartwoods. Silica gel column chromatography of the cumaru-ferro EtOAc extract yielded (−)-(3R)-7,2′,3′-trihydroxy-4′-methoxyisoflavan and (+)-(3R)-8,2′,3′-trihydroxy-7,4′-dimethoxyisoflavan. Silica gel column chromatography followed by preparative high-performance liquid chromatography of the jatoba EtOAc extract yielded (−)-fisetinidol and (+)-trans-taxifolin. Chemical structures were assigned using electron-ionization mass spectrometry, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy including nuclear Overhauser effect spectroscopy (NOESY), as well as optical rotation and circular dichroism. Gas chromatography-mass spectrometry demonstrated that the isolated compounds were predominant in the EtOAc extracts. In the guarita EtOAc extract, catechin and gallic acid were identified by comparing their retention times and mass fragmentation patterns with those of authentic samples. Antioxidant activity determined by the 1,1-diphenyl-2-picrylhydrazyl assay demonstrated that all these compounds had activities comparable with that of α-tocopherol. Part of this report was presented at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007     

Biosafety assessment of transgenic poplars overexpressing xyloglucanase (AaXEG2) prior to field trials

We performed biosafety assessments of transgenic poplars prior to field trials. Constitutive expression of the Aspergillus aculeatus xyloglucanase in Populus alba increased the cellulose content and specific gravity of its stem, the leaves of which were visibly greener, thicker, and smaller than those of the wild-type plant. Although the young transgenic poplars grew faster than the wild type in a growth chamber, there was no distinguishable difference in growth between the poplars when they were placed in a special screened greenhouse. Allelopathic tests showed that the transgenic poplars do not produce harmful substances. Based on all the biosafety assessments and the scientific literature on poplar species, we came to the conclusion that transgenic poplars probably do not disturb the biological diversity of the surrounding environment, even when they are submitted to field trials.     

The effect of openings on combined bound water and water vapor diffusion in wood

This study was undertaken to estimate the effect of openings between cell walls on combined bound water and water vapor diffusion in wood. Using a newly developed model, the radial and tangential moisture diffusion coefficients can be predicted depending on the opening area. The new model explicitly involves a term for water vapor diffusion through the openings, as well as a term for the combined diffusion of bound water and water vapor. A classical model developed by Stamm and Choong had higher longitudinal moisture diffusion coefficients than that in the parallel model at higher moisture content, which is inconsistent with the Wiener bound rule. The new model suggested in this article is useful for analyzing the experimental results and understanding the variability of the diffusion coefficients.