木质纤维同步糖化共发酵产燃料乙醇过程优化

经蒸汽爆破预处理的杨木为原料进行同步糖化共发酵(SSCF)法产乙醇。使用里氏木霉Rut C-30产纤维素酶,滤纸酶活(FPA)与纤维素酶产酶速率最大值分别为6.283 IU/mL、0.035 IU/mg.h。同步糖化共发酵中,重组大肠杆菌(KO11)与酿酒酵母的混合发酵乙醇产量高于单菌种发酵。乙醇含量随残糖量的降低而逐渐升高。底物浓度为5%和10%时,乙醇含量最高值分别为8.97 g/L和13.98 g/L,乙醇得率分别为53.8%和41.9%。     

变风补料对里氏木霉产纤维素酶的影响

为应对资源短缺及环境问题,生物质作为可再生生物资源越来越受到关注。纤维素酶催化纤维素水解为葡萄糖是生物转化的关键环节。为提高纤维素酶的生产能力,在分批补料产酶过程中改变各阶段通风量,控制发酵液溶氧量,促进菌丝体的生长及酶的合成。以微晶纤维素为碳源,里氏木霉(Trichoderma reesei)Rut C30为产酶菌株,分批补料生产纤维素酶,摇瓶滤纸酶活达到14.5 U/m L。在3 L的发酵罐中,恒定通风量,分批补料生产纤维素酶,酶活第10天达到13.7 U/m L。对纤维素酶生产各阶段的通风量进行调整和优化,当通风量第1天为20 L/(L·h)、第2~3天为30 L/(L·h)、第4天及以后为25 L/(L·h)时,发酵液溶氧水平得到明显改善,稳定在15%~30%,菌丝体浓度稳定,滤纸酶活达到18.3 U/m L,纤维素酶产率为93.5 U/(L·h),纤维素酶得率为481.6 U/g微晶纤维素。纤维素酶活提高了33.6%,周期缩短2 d。缩短补料周期至8 h,滤纸酶活达到18.5U/m L,提高35%。通过控制通风量,提高纤维素酶产率,降低纤维素酶的生产成本,促进工业化酶制备。     

低聚木糖生产废渣纤维素酶诱导和水解特性的研究

研究了生产低聚木糖(XOS)所得的废渣对里氏木霉纤维素酶合成的诱导作用和纤维素酶水解特性.废渣对里氏木霉合成纤维素酶的诱导作用较差,而纤维素酶水解性能优异.里氏木霉以含纤维素15 g/L的废渣为碳源合成纤维素酶,滤纸酶活为0.48 FPIU/mL,酶产率为6.67 FPIU/(L·h),酶得率为每克纤维素32.00 FPIU,而在相同条件下以玉米芯为碳源时滤纸酶活为3.20 FPIU/mL、酶产率19.00 FPIU/(L·h)和酶得率每克纤维素213.33 FPIU.质量浓度为20 g/L的废渣在酶用量为每克纤维素10 FPIU条件下水解24 h,水解得率达92.8 %;底物废渣质量浓度为100 g/L时,48 h纤维素酶水解得率达到80.6 %.     

白腐菌预处理对丙酸蒸解玉米芯制备纤维素的影响

探讨了白腐菌预处理对丙酸蒸解法制取纤维素的影响.在白腐菌对玉米芯进行预处理过程中,赖锰过氧化物酶(MnP)、木质素过氧化物酶(LiP)、漆酶、木聚糖酶和纤维素酶的酶活分别在第5、 6、 7、 10和 15 d 达到最高值,分别为1.326、 10.25、 0.062 7、 0.33和 403 U/g.利用响应面分析法确定丙酸蒸解玉米芯最佳工艺条件为:料液比1∶ 10(g∶ mL),蒸解时间 70 min,丙酸质量浓度 900 g/L,产物中纤维素的质量分数为 91.09%.玉米芯经白腐菌预处理 10 d 后再用丙酸进行蒸解处理,产物中纤维素的质量分数和保留率分别为 97.12% 和 94.70%,而半纤维素和木质素的质量分数仅为 0.96% 和 0.92%.     

I-optimal混匀实验设计制备肉桂叶饲用化复合食用菌菌剂

为进一步提高肉桂叶发酵过程中各种饲用酶活性,通过I-optimal混匀设计考察了不同食用菌菌种间,以及食用菌与米曲霉间混合发酵产饲用酶活性的协同与拮抗效应。研究结果表明:特殊立方模型可以作为实验设计的回归模型,拟合结果可靠。在平菇、金针菇、木耳与米曲霉间,金针菇与木耳的菌丝产酶过程中存在拮抗效应,其余菌种生长过程中显示出明显的协同效应。通过数值优化算法得出2个最佳接种配比方案:配方一为17.6%木耳、44.4%平菇和38.0%米曲霉,对应的木聚糖酶酶活为9.14 U/g、纤维素酶酶活为1.56 U/g、植酸酶酶活为67.37 U/g;配方二为60%金针菇和40%米曲霉,对应的木聚糖酶酶活为5.74 U/g、纤维素酶酶活为1.34 U/g、植酸酶酶活为58.39 U/g。     

亚硫酸盐蔗渣浆酶解工艺及外源物辅助作用的研究

以亚硫酸盐蔗渣浆为研究对象,研究了底物浓度、外源添加物种类和浓度对纤维素酶解工艺的影响以及PEG6000强化酶解效率的作用机理。研究结果表明,纤维素酶用量15 FPIU/g(以绝干纤维素计,下同)、β-葡萄糖苷酶用量30 CBU/g,纤维素质量浓度80 g/L条件下水解48 h,葡萄糖质量浓度达72.51 g/L,葡萄糖得率、纤维素酶解得率和总糖得率达81.58%、86.79%和84.23%。PEG6000可有效强化酶解,添加量为2 g/L时,水解48 h葡萄糖质量浓度可升至78.54 g/L,葡萄糖得率、纤维素酶解得率和总糖得率达88.36%、95.02%和92.54%。添加2 g/L的PEG6000使纤维素酶Celluclast1.5 L滤纸酶活力提高到原酶活力的117.33%;同时50℃,pH值4.8,保温48 h,残余酶活力同比增加38.99%。     

The Study about Enzymatic Hydrolysis of Bagasse Sulfite Pulp and the Assistant Effect of Additives

以亚硫酸盐蔗渣浆为研究对象,研究了底物浓度、外源添加物种类和浓度对纤维素酶解工艺的影响以及PEG6000强化酶解效率的作用机理.研究结果表明,纤维素酶用量15 FPIU/g(以绝干纤维素计,下同)、β-葡萄糖苷酶用量30 CBU/g,纤维素质量浓度80 g/L条件下水解48 h,葡萄糖质量浓度达72.51 g/L,葡萄糖得率、纤维素酶解得率和总糖得率达81.58％、86.79％和84.23％.PEG6000可有效强化酶解,添加量为2g/L时,水解48 h葡萄糖质量浓度可升至78.54 g/L,葡萄糖得率、纤维素酶解得率和总糖得率达88.36％、95.02％和92.54％.添加2g/L的PEG6000使纤维素酶Celluclast 1.5 L滤纸酶活力提高到原酶活力的117.33％;同时50℃,pH值4.8,保温48 h,残余酶活力同比增加38.99％.     

不同菌种对油橄榄叶发酵饲料的影响

以黑曲霉、白地霉、米曲霉、绿色木霉、产朊假丝酵母和热带假丝酵母为固态发酵菌种,考察单菌及混合菌种对油橄榄叶发酵饲料中纤维素酶活(β-葡萄糖苷酶活、羧甲基纤维素酶活及滤纸酶活),蛋白质及总单宁含量的影响。结果表明,单菌发酵效率最高的菌种为黑曲霉,发酵3天时纤维素酶活最高,β-葡萄糖苷酶活10.53 U/m L、羧甲基纤维素(CMC)酶活10.61 U/m L、滤纸(FPA)酶活4.02U/m L,发酵5天时蛋白质最高达14.61%,发酵7天总单宁降解率最高达84.14%;混菌发酵效率最高的为黑曲霉与产朊假丝酵母的组合,其最佳比例为1∶1(体积比),发酵时间5天,纤维素酶活最高,β-葡萄糖苷酶活12.45 U/m L、CMC酶活12.59 U/m L及FPA酶活5.51 U/m L,发酵7天时蛋白质最高可达18.63%,总单宁降解率最高为86.49%。     

蒸汽预处理玉米秸秆酶水解速率下降的因素分析

为评价导致纤维素酶水解速率下降的因素,以底物质量浓度为50 g/L葡聚糖及酶用量为20 FPIU/g滤纸酶活和10 IU/g β-葡萄糖苷酶活的蒸汽预处理玉米秸秆酶水解为研究对象,探讨了影响酶水解速率的潜在因素,包括物料反应性能、纤维素酶非特异性吸附、酶失活及终产物抑制。结果表明：酶用量40 FPIU/g条件下酶水解6 h及12 h后,蒸汽预处理玉米秸秆的物料反应性能分别下降了16.0%及23.7%,然而,在酶用量为20 FPIU/g时,物料反应性能的下降对酶水解速率的影响极其有限;酶解木质素的添加使得1 h酶解上清液中酶蛋白浓度降低了20.8%,但初始酶水解速率并未显著降低,即木质素对纤维素酶的非特异性吸附对酶水解速率影响不大;两段酶水解中纤维素酶的更新使得7h酶水解速率由一段酶水解中的1.30 g/(L·h)提高至1.83 g/(L·h);两段酶水解中终产物的去除则使得7 h酶水解速率提高至4.76 g/(L·h),是一段酶水解中7 h酶水解速率的3.66倍。综合而言,酶失活及终产物抑制对酶水解速率影响较大,其中终产物抑制是导致蒸汽预处理玉米秸秆酶水解速率降低的关键因素。     

蒸汽预处理玉米秸秆酶水解速率下降的因素分析（英文）

为评价导致纤维素酶水解速率下降的因素,以底物质量浓度为50 g/L葡聚糖及酶用量为20 FPIU/g滤纸酶活和10 IU/gβ-葡萄糖苷酶活的蒸汽预处理玉米秸秆酶水解为研究对象,探讨了影响酶水解速率的潜在因素,包括物料反应性能、纤维素酶非特异性吸附、酶失活及终产物抑制。结果表明:酶用量40 FPIU/g条件下酶水解6 h及12 h后,蒸汽预处理玉米秸秆的物料反应性能分别下降了16.0%及23.7%,然而,在酶用量为20 FPIU/g时,物料反应性能的下降对酶水解速率的影响极其有限;酶解木质素的添加使得1 h酶解上清液中酶蛋白浓度降低了20.8%,但初始酶水解速率并未显著降低,即木质素对纤维素酶的非特异性吸附对酶水解速率影响不大;两段酶水解中纤维素酶的更新使得7 h酶水解速率由一段酶水解中的1.30 g/(L·h)提高至1.83 g/(L·h);两段酶水解中终产物的去除则使得7 h酶水解速率提高至4.76 g/(L·h),是一段酶水解中7 h酶水解速率的3.66倍。综合而言,酶失活及终产物抑制对酶水解速率影响较大,其中终产物抑制是导致蒸汽预处理玉米秸秆酶水解速率降低的关键因素。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.