96 resultados para 5-40


Relevância:

60.00% 60.00%

Publicador:

Resumo:

研究了不同孵育温度对黄喉拟水龟(MauremysmuticaCantor)性别决定的影响,同时分析了孵育温度对胚胎发育及成活率的影响。实验设置的3个孵化温度为(25±0.5)℃,(29±0.5)℃和(33±0.5)℃。每一温度指标下设置40枚受精卵。在实验温度内,胚胎的发育速度随着孵化温度的升高而加快,所用的孵育时间也越来越短。孵化累积温度CTUs在25℃时最高,在29℃时最低,而33℃时则居中,在25℃和29℃时,孵化成活率较高,均达到97.5%。在33℃时孵化成活率只有67.5%,而在孵出的稚龟中亦有

Relevância:

60.00% 60.00%

Publicador:

Resumo:

研究了沙坡头藻结皮中的优势物种——微鞘藻的胞外多糖对沙漠表层土壤水分分布状况的影响及其光合特性。随着胞外多糖浓度的升高 ,土壤持水量增大 ,土壤水分蒸发速率降低 ,水分在土壤中运动的速率被延缓。藻总水溶性多糖产率为 2 8.82 % ,胞外水溶性多糖产率为 1 6 .0 9% ;多糖产量在稳定期生物量最大时增长最快。微鞘藻光合作用最适温度为 2 5℃ ,最适光强为 40 0 μE.m- 2 .s- 1,在 0 .3 mol/ L Na Cl浓度下其光合作用活性被强烈抑制 ;微鞘藻的吸收光谱表明它比生长在湿

Relevância:

60.00% 60.00%

Publicador:

Resumo:

在鄂西的五峰、宜都、宜昌、当阳及神农架林区一带,采集到裸藻门植物16属140种(包括变种和变型)。属于绿色裸藻类的有116种,无色裸藻类的有24种,其中有5个新种,7个新变种,3个新变型,有20种是我国新记录。在采集区域内的地形大体上可以分成三种不同的类型,即:山岳地区(采得裸藻5种),河谷盆地地区(采得裸藻40种)和沿长江丘陵地区(采得裸藻128种)。静止水体由于地形的差异,体积的大小和水质的肥沃程度不同,都对裸藻门植物的生长有重要的影响。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

<正> 雄健的身躯、鲜艳的色彩、华丽的斑纹、潇洒的泳姿、温顺的习性、武士的风度,这都是锦鲤所特有的魅力,也是其爱好者不断增加的原因所在。首先让我们欣赏那锦鲤的正统代表“红白”,高雅明朗的红色斑纹镶嵌在纯净白皙的皮肤上,鲜艳夺目,在1965~1980年每年一次的全日本锦鲤品评会上,曾八次名冠群雄,荣获冠军——总理大臣奖。它们有的

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A L9 orthogonal array design involving 3 factors (C6H12O6, KNO3 and NaH2PO4) and 3 levels for each (C6H12O6: 0.2, 0.4 or 0.8 g/L; KNO3: 0.4, 0.8 or 1.6 g/L, NaH2PO4: 0.05, 0.1 or 0.2 g/L), was used to study the effects of nutrients on dehydrogenase activity and polysaccharide content of substrate biofilms in the integrated vertical-flow constructed wetland (IVCW). Results showed that C6H12O6 and KNO3 were the main factors for dehydrogenase activity and polysaccharide content of biofilms, respectively. The combinations of three nutrients at different concentrations had different effects on dehydrogenase activity and polysaccharide content of biofilms. The optimal combination for dehydrogenase activity was obtained by locating the concentrations Of C6H12O6, KNO3 and NaH2PO4 at 0.2, 0.8 and 0.05 g, and the optimal combination for polysaccharide content was obtained by locating the concentrations Of C6H12O6, KNO3 and NaH2PO4 at 0.2, 0.4 and 0.2 g/L, respectively. The corresponding maximum activity and polysaccharide content were 5.40 mu g TF/g substrate/12 h and 3454.6 mu g/g substrate, respectively. These results would provide the laboratory foundation for optimizing the purification function of the wetland systems.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Tributyltin (TBT) is widely used as antifouling paints, agriculture biocides, and plastic stabilizers around the world, resulting in great pollution problem in aquatic environments. However, it has been short of the biomonitor to detect TBT in freshwater. We constructed the suppression subtractive hybridization library of Tetrahymena thermophila exposed to TBT, and screened out 101 Expressed Sequence Tags whose expressions were significantly up- or down-regulated with TBT treatment. From this, a series of genes related to the TBT toxicity were discovered, such as glutathione-S-transferase gene (down-regulated), plasma membrane Ca2+ ATPase isoforms 3 gene (up-regulated) and NgoA (up-regulated). Furthermore, their expressions under different concentrations of TBT treatment (0.5-40 ppb) were detected by real time fluorescent quantitative PCR. The differentially expressed genes of T thermophila in response to TBT were identified, which provide the basic to make Tetrahymena as a sensitive, rapid and convenient TBT biomonitor in freshwater based on rDNA inducible expression system. (c) 2006 Elsevier B.V. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

为评价宁南山区草地植被不同恢复方式对土壤入渗性能的影响,以不同植被群落的饱和导水率为研究对象,采用逐步回归研究退耕农地、禁牧荒地、封育草地导水率的变化及影响因子,并探讨了其作用机制。结果表明:3种植被恢复方式均有利于0~40 cm土壤饱和导水性能提高;各土层土壤饱和导水率均随植被恢复而不断提高,0~5 cm土层改善作用最为明显;农地退耕序列和荒地禁牧序列5~40 cm土层、封育草地序列0~40 cm土层土壤饱和导水率随土层深度下降而降低;影响土壤饱和导水率的因子为土壤有机质因子和土壤结构因子;3种植被恢复方式土壤有机质质量分数与Ks均呈显著的线性相关关系,在该区域有机质质量分数越高,Ks增加越快;土壤有机质积累是土壤饱和导水率提高的根本动力。因此,草地封育更利于提高使该地区土壤导水性能提高,促进生态恢复。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

在干旱半干旱地区,砂石覆盖作为一项传统的覆盖技术,可以明显减少土壤蒸发,为作物生长提供良好的水分条件。为研究不同粒径和厚度砂石覆盖对土壤蒸发的影响,进行了室内模拟试验,对3种粒径(2.5~10、10~25和25~40 mm)和2种覆盖厚度(8 cm和14 cm)以及不同粒径砂石配比条件下土壤水分蒸发进行了研究。结果表明,砂石覆盖能有效地抑制土壤蒸发,在土壤含水量较高的阶段,这种抑制作用更加明显。砂石覆盖对土壤蒸发的抑制作用与粒径和覆盖厚度密切相关,在2.5~40 mm粒径范围内,随着砂石粒径的增大,砂石覆盖对蒸发的抑制作用降低,对蒸发过程的影响减弱,覆盖厚度越大,蒸发量越小。有效的砂石配比应选择细砂石处理,不宜过粗。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

选择植被自然恢复不同年限的阳坡梁坡地作为研究对象,采用时空互代法研究子午岭地区植被恢复过程中土壤养分和酶活性的变化。结果表明,植被恢复140 a内,不同土层土壤有机质含量、全氮含量、蔗糖酶活性、脲酶活性、碱性磷酸酶活性和过氧化氢酶活性增加,且表土层(0~20 cm)土壤养分含量和酶活性高于下层土壤(20~40 cm)。以裸露地为对照,土壤0~20 cm土层,有机质含量、全氮含量、蔗糖酶活性、脲酶活性、碱性磷酸酶活性和过氧化氢酶活性分别增加了23.8%~534.9%、9.3%~300.0%、213.6%~521.5%、40.4%~286.5%、22.7%~232.2%和3.2%~22.4%,土壤速效磷含量呈现波动变化,过氧化氢酶活性变化幅度比其他三种酶低。土壤有机质含量与全氮、速效磷含量密切相关;土壤蔗糖酶与土壤有机质、全氮均为极显著的相关关系(0.930/0.918);土壤脲酶活性与全氮含量相关系数最高(0.804);土壤碱性磷酸酶活性与有机质、全氮含量都呈极显著相关(0.977/0.984);土壤过氧化氢酶活性与全氮含量极显著相关,相关系数达0.996。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

本文试图用Solvay型的Ziegler-Natta催化剂合成PP-EPR,PP-EPR-PP嵌段共聚物,作为乙丙橡胶(EPT)和聚丙烯(PP)的增容剂,来提高聚丙烯的抗冲击强度,并从力学性能、动态力学谱和形态等方面研究增容剂的增容效果。Ziegler-Natta催化剂能否合成乙丙嵌段共聚物是一个有争议的问题。为此,我们利用改进型的Solvay δ-TiCl_3-Et_2AlCl在已烷中加压淤浆聚合丙烯,发现在120分钟之前,聚丙烯的分子量随时间迅速增加,超过120分钟则变缓慢,并趋向于平衡。这说明催化剂活性中心上的活性链最小有120分钟的时间,若在该时间内用聚合过程中换反应单体的办法,有可能合成嵌段共聚物。乙丙嵌段共聚物形成的直接证明是利用(PP-PE)_(50)。通过气相色谱检测发现,抽真空3分钟可以保证换反应气体的纯度,因而用气相聚合可以得到各段纯净的(PP-PE)_(50)多嵌段共聚物,该嵌段的~(13)c-NMR研究表明,在35.68ppm处存在以化学键相连的长乙烯和长丙烯链的特征共振峰。PGC的研究发现,其在热裂解中产生的G碎片比PP/P混物的多,GC-MS的研究表明G碎片由含7个碳的烃组成的混合物,组分之一具有嵌段共聚物的裂解特征。对PP-EPR系列产物和PP-EPR-PP(5-60-20)用扭摆法进和动态力学分析表明,这些嵌段共聚物只在-30℃左右有一个玻璃化转变。而相应的共混物则分别在-50℃和5℃出现两个玻璃化转变,且各T_g不随组成比和共混方法而变化。这是由于嵌段共聚物中各段间化学键的作用,使各段的T_g内移,从而使较靠近的两个T_g合二为一,在动态力学谱上只表现出一个T_g。粘弹谱仪测定的结果基本上同扭摆法的结果。尽管我们尚未准确地测定出乙丙嵌段共聚物中EPR段的分子量,但我们弄清了PP段的立体构型、等规度、分子量、结晶度和EPR段的乙丙比、无规乙丙共聚物的含量、含有长序列乙烯的结晶度等结构因素。用不同段长的PP-EPR作PP/EPT共混物的增容剂,发现降低PP-EPR中PP段的分子量,三元共混物的力学性能明显升高,而增加EPR段的分子量即聚合时间,其无缺口冲击强度先增加而后又降低,说明有一个EPR段最佳长度范围。根据该现象我们提出模型并进行了解释。结晶度的规律与冲击强度的规律相同,对冲击强度提高较大的增容剂,共混物中PP的结晶度降低,但抗张性能却升高,说明增容剂在两相界面起到主价的连接作用。扭摆法和粘弹谱仪测定的动态力学谱表明,增容剂的加入减小了聚丙烯结晶无序化转变,使PP的T_g突出出来。形态的研究说明,PP-EPR还起了“乳化剂”的作用,使EPT在PP连续相中均匀分散,且其微区大小适中。在PP/EPT(85/15)中加入4%的PP-EPR(5-30)嵌段共聚物,室温(20℃)的“冲击屈服强度”与PP/EPT的相同,-20℃的冲击强度为112kg·cm/cm~2,是PP/EPT的1.5倍,-40℃为72kg·cm/cm~2,是PP/EPT的1.9倍,在应力-应变实验中,三元共混物PP/EPT/PP-EPR(5-30)的σ_b*ε_b为2.97*10~5。比相应的PP/EPT(2.27*10~5)有所提高。说明PP-EPR(5-30)对PP/EPT有良好的增容效果,比文献中使用的PP-EPR(15-55)效果好。用PP-EPR-PP三嵌段共聚物作PP/EPT的增容剂,实验证明比PP-EPR二嵌段共聚物有更好的增容效果。例如,在PP/EPT(85/15)中加入4%的PP-EPR-PP(5-60-20),试样不但在20℃,而且在-20℃均未被冲断;在-20℃的“冲击屈服强度”是PP/EPT冲击强度的1.4倍,PP的9.0倍,-40℃的冲击强度是PP/EPT的2.2倍,PP的8.4倍;且其σ_b*ε_b(2.62*10~5)比PP/EPT(2.60*10~5)的有一定的提高,比PP的(2.45*10~5)也高。对PP/EPT/PP-EPR-PP(5-60-20)三元共混物的试样在-40℃冲断面的形态进行研究表明,加入增容剂的共混物断面凹凸不平,是韧性断裂的特征,且在断裂过程中EPT微区被牵拉出的EPT较多,说明PP和EPT的相界面的作用力较大,增容剂起到了主价键的连接作用。动态力学谱表明,增容剂的加入降低了PP结晶无序化转变。而液氮冷冻的脆断面的形态说明,PP-EPR-PP起到了“乳化剂”的作用,使EPT在PP连续相中大小均匀地分散开。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

黑颈鹤中部越冬种群是三个越冬种群中最为濒危的一个。由于栖息地退化和 丧失等因素的影响,其分布区逐渐萎缩,在大多数分布区(大理、鹤庆、丽江、 祥云),黑颈鹤已经消失或偶见。目前稳定的越冬区仅见于香格里拉县境内的纳 帕海和碧塔海,其中90%以上的个体在纳帕海越冬。纳帕海已经成为中部种群最 重要的越冬地。 本论文主要报道了2007 年~2010 年有关种群数量、空间利用模式、栖息地 偏好以及迁徙生态等工作成果。 1) 纳帕海黑颈鹤种群呈增长态势,数量由2004 年的281 只增长到2007 年的325 只。但2007 年的幼体新增率仅为8.1%,大大低于2004 年的16.3%。 这也说明黑颈鹤繁殖的成功率在不同的年份波动比较大。 2) 黑颈鹤在纳帕海的总利用区域(100%等值线)面积为990.9ha,而核心 利用面积(50%等值线)仅为42.3ha,分别占总研究区域的28.2%和1.2%。每个 月的平均90%利用区域面积为217.5 ±40.8ha (值域= 108.0~317.4ha, N = 5 个 月) ,月平均核心利用区域为25.5 ±5.1ha (值域=10.4~38.6ha, N = 5 个月)。 涝季和旱季相比,黑颈鹤的总利用区域和核心利用区的面积没有显著差异(t-检 验,P 均>0.05)。在不同的月份黑颈鹤会利用不同的区域,任意两月的总活动面 积重叠率为39.1 ±3.8% (值域= 21.3~57.2%),而核心活动面积重叠率仅为9.9 ±3.0%(值域= 0~28.5%)。栖息地的改变对黑颈鹤的空间利用造成较大的影响, 随着明水面由南向北退却,黑颈鹤的活动区域也随之移动。 3) 黑颈鹤对各栖息地具有选择性。使用欧几里德距离法分析表明黑颈鹤偏 好浅水沼泽和湿草甸,而回避耕地和干草地。这种偏好性不随季节而改变。 4)通过卫星跟踪发现:黑颈鹤具有相似的春季和秋季迁徙路线,但花费的 时间差异较大,春季时仅需1~2 天,而秋季时则花费了1~20 天。在迁徙过程 中,黑颈鹤通过山区时,沿河流飞行,在高原面上则顺低谷迁徙,迁徙中回避海 拔较高的高山,而多沿海拔较低的山谷飞行,在翻越高山时也选择较低的山隘口 通过。 根据研究的结果,提出如下保护建议:将黑颈鹤的核心利用区划为保护区的 核心区;重点保护浅水沼泽栖息地,在越冬期应该稳定保持一定面积的沼泽;规 范旅游管理,减少游客对黑颈鹤造成的干扰;开展家猪对湿地影响的研究,确立 合适的散养数量。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

环境因子及土著根瘤菌是影响人工接种根瘤菌剂接种效果的两个主要因素。论文分为二部分。第一部分首先考察了外界因素对根瘤菌剂接种效果的影响。应用GUS(葡萄糖苷酶)基因标记技术将标记基因GUS导入受体菌S.fredii 8855,标记菌体形成的根瘤可被GUS染色缓冲液染成兰色,而土著菌形成的根瘤不能着色,由此即可十分简便地确定土著菌的影响程度。盆栽实验表明,S.fredii 8855的结瘤抗酸碱能力高于土著菌,能在土壤中较大范围内迁移。当它的根瘤占有率不小于43%时,接种能显著提高大豆产量。大豆产量与根瘤根瘤占有率呈正相关(r = 0.98),而与总瘤数关系不大(r = 0.13)。土壤氮素显著抑制其结瘤,补加磷能缓解这种抑制作用。研究发现应用快生型大豆根瘤菌剂为保证接种效果,接种量至少应为土著根瘤菌数量的10~5倍,同时施用磷肥会提高接种效果。只有当接种根瘤菌的占瘤率在40%以上时接种才可能达到增产目的。第二部分较为系统地考察了新疆主要大豆产区耕作土中大豆根瘤菌种群数量、种群结构及种群共生、遗传多样性。新疆大豆地耕作土中含有数量较高的大豆根瘤菌,数量每克土大多在10~5-10~6之间,种群结构大多以快生型根瘤菌为主。对分离的28株根瘤共生及遗传多样性进行了分析,土著大豆根瘤菌菌株间结瘤能力有一定差异,快生型大豆根瘤菌总体结瘤能力高于慢生型,但差异不显著(p <= 0.05),形成的根瘤大小也有较大差异。根瘤菌种群中菌株间为植物提供的生物固氮量存在明显差别,但仅有20%的菌株能明显促进植物生长,有1/3的菌株具有较高的固氮能力。慢生型大豆根瘤菌固氮能力明显高于快生型,但二者之间差异未达到显著水平(p < 0.05)。根瘤菌结瘤力与固氮活性之间的相关性分析发现许多根瘤菌形成的根瘤为无效根瘤。重复序列(重复基因外回文REP和肠细菌重复基因间共同序列ERIC)结合聚合酶链式反应(ERP和ERIC-PCR)用于大豆根瘤菌染色体指纹分析,分析结果表明新疆土著大豆根瘤菌具有复杂的遗传多样性,遗传相近程度具有一定的地域性,来自同一地区的根瘤菌株具有较高的遗传相似性。新疆土著大豆根瘤菌在相似水平0.5可分为两大类群,一个类群包括所有慢生型根瘤菌,另一类群为所有快生型根瘤菌。在相似水平0.6大豆根瘤菌可分为5个聚群,快生型根瘤菌分为二个主要聚群和一个次要类群,慢生型根瘤菌分为二个次要类群。主要聚群中一个聚群结瘤能力较高但固氮能力较低,另一聚群结瘤能力和固氮量均较低;次要聚群中快生型和一个慢生型聚群固氮能力较高但结瘤力低,另一慢生型聚群固氮能力和结瘤力均较高。以上研究表明,新疆绿洲农业生态系统中大豆根瘤菌具有一定种质特异性,尽管次要类群具有相对较高的因氮活性,但由于多数根瘤菌形成的根瘤为固氮活性很低的无效根瘤,占优势的主要聚群固氮活性较低,因此土著根瘤菌生物固氮量不能满足作物对氮素的需求,在新疆人工施用根瘤菌剂具有现实意义,但接种的根瘤菌剂可能受到对环境适应性强、结瘤能力高的土著根瘤菌优势类群强有力的竞争。

Relevância:

60.00% 60.00%

Publicador:

Resumo:

生物质燃料乙醇是一种高度清洁的交通液体燃料,是减少温室气体排放,缓解大气污染的最佳技术选择。以非粮原料生产燃料乙醇可以在进行能源生产的同时保证粮食安全,有利于产业的可持续发展。在众多的非粮原料中,甘薯是我国开发潜力最大的生物质能源作物之一。我国占世界甘薯种植总面积和产量的90%。同时,甘薯的单位面积燃料乙醇产量远大于玉米和小麦。其成本是目前酒精中最低廉的,因此利用甘薯生产乙醇是发展生物质燃料乙醇的首要选择。目前采用薯类全原料主要采用分批发酵生产乙醇,其技术水平低,发酵强度低,一般在0.7-2.5g/(L•h),乙醇浓度低,甘薯发酵乙醇为6-8%(v/v),能耗高,环境负荷大,污染严重。针对上述问题,本文从菌株选育、原料预处理、中试放大、残糖成分分析等方面进行研究。 为了研究乙醇发酵生产规模扩大过程中,大型发酵罐底部高压条件下,CO2对酵母乙醇发酵的影响,我们通过CO2 加压的方法进行模拟试验,研究结果表明,发酵时间随压强的升高而逐渐延长,高压CO2 对乙醇发酵效率影响不大,在0.3 MPa 以下时,发酵效率均可达到90%以上。高压CO2 对发酵的抑制作用是高压和CO2 这两个因素联合作用的结果。高压CO2 条件下,酵母胞外酶和胞内重要酶类的酶活均表现出特征性。0.2 MPa 下,酶活性的变化趋势和0.1 MPa 条件下的较为一致。而0.3 MPa 下的酶活变化趋势与0.4 MPa 下的酶活更为接近。通过全基因表达分析发现在CO2 压力为0.3 MPa 下,乙醇发酵途径中多个基因表达量下调,同时海藻糖合成酶和热激蛋白基因表达量上调。 筛选耐高温的乙醇酵母菌株能够解决糖化温度和发酵温度不协调的矛盾,实现真正意义上的边糖化边发酵。高温发酵还能够降低发酵时的冷却成本,实现乙醇的周年生产。本研究筛选出一株高温发酵菌株Y-H1,进而我们对该菌株的胞外酶和胞内乙醇代谢重要酶类的酶活性进行了分析。结果表明Y-H1 能够在40 ℃条件下正常进行乙醇发酵,发酵33h,最终乙醇浓度达到10.7%(w/w),发酵效率达到90%以上。同时发酵液最终pH 在3.5 左右,显示菌株具有一定的耐酸性能力。同时观察到40 ℃下,菌株的胞外酶和胞内乙醇代谢重要酶类的酶活性发生了变化,乙醇发酵途径中关键酶基因表达下调,而海藻糖合成酶与热激蛋白基因表达量上调,这些结果为进一步研究酵母菌耐热调控机理提供了依据。 糖蜜是一种大规模工业生产乙醇的理想原料,本研究利用选育高浓度乙醇发酵菌株结合配套的发酵稳定剂,研究了糖蜜高浓度乙醇发酵情况。结果表明采用冷酸沉淀预处理糖蜜溶液,采用分批补料的发酵方式,乙醇浓度最高达到了10.26% (w/w),发酵时间为42 h。同时观察到在糖蜜发酵中,乙醛含量与乙醇浓度存在一定的相关性。 快速乙醇发酵对于缩短乙醇生产周期、降低乙醇生产成本、减少原料腐烂损失具有重要意义。本研究诱变和筛选得到了一株快速乙醇发酵菌株10232B。在优化后的发酵条件下,采用10L 发酵罐进行分批乙醇发酵,经过18h,乙醇的最终浓度达到88.5g/L,发酵效率93.6%,平均乙醇生产速度达到4.92 g/L/h。此菌株在保持较高乙醇生产浓度的同时,拥有快速生产乙醇的能力,适合作为快速乙醇发酵生产菌种。 由于鲜甘薯具有粘度大的特点,传统液化糖化处理很难在短时间内充分糖化原料;高粘度的醪液也难以进行管道输送,容易堵塞管路;同时,也会降低后续的乙醇发酵效率。 本文采用了快速粘度分析法对鲜甘薯糊化粘度特性进行了分析,进而对预处理条件进行了研究,在最佳预处理条件下,糖化2h 后,醪液葡萄糖值最高可达99.3,粘度4.5×104 mPa.s,而采用传统糖化工艺,醪液DE 值仅为85.8,粘度大于1.0×105 mPa.s。 此预处理方法也可用于快速糖化不加水的醪液。后续的乙醇发酵试验表明,通过此预处理方法获得的糖化醪液对乙醇发酵无负面影响。 在前期已实现了实验室水平的鲜甘薯燃料乙醇快速乙醇发酵基础上,进一步将发酵规模扩大到500L,在中试水平上对甘薯乙醇发酵进行了研究。结果表明在500L 中试规模,采用边糖化边发酵(SSF)工艺,在料液比为3∶1,发酵醪液最高粘度为6×104mPa.s 条件下,发酵37h,乙醇浓度达到了12.7%(v/v),发酵效率91%,发酵强度为2.7 g/(L•h)。与目前国内的薯类乙醇发酵生产技术水平具有明显的优越性。 为研究甘薯、木薯乙醇发酵中残糖的组成,采用了高效液相色谱—蒸发光散射检测法,对乙醇发酵残糖进行了分析。结果表明,甘薯、木薯乙醇发酵残糖均为寡聚糖,主要由葡萄糖、木糖、半乳糖、阿拉伯糖和甘露糖构成。随着发酵时间延长,寡聚糖中的葡萄糖、半乳糖、甘露糖可被缓慢的水解释放。提高糖化酶量仅在一定程度上降低残糖,过量的糖化酶反而会导致残糖增加。同时发现3, 5-二硝基水杨酸法不能准确测定甘薯、木薯乙醇发酵中的残总糖含量。进一步筛选了两株残糖降解菌株,对甘薯乙醇发酵残糖的降解利用率均达到了40%以上,而且还能显著降低发酵醪液粘度。经形态学和rRNA ITS 序列分析,确定这两株菌分别属于为木霉属和曲霉属黑曲霉组。 通过对以甘薯原料为代表的非粮原料发酵技术研究开发,以期形成乙醇转化率高,能耗低,生产效率高、季节适应性好,原料适应性广,经济性强,符合清洁生产机制的燃料乙醇高效转化技术,为具有我国特色的燃料乙醇发展模式提供技术支持。 Sweet potato is one of the major feedstock for the fuel ethanol production in China. The planting area and the yield in China take 90% of the world. Sweet potato is an efficient kind of energy crops. The energy outcome per area is higher than corn or wheat. And the manufacture cost of ethanol is the lowest, compared with corn and wheat. So sweet potato is the favorable crop for the bioethanol production in China. However, the low-level fermentation technology restricts the development of ethanol production by sweet potato, including slow ethanol production rate, low ethanol concentration and high energy cost. To solve these problems, we conducted research on the strain breeding, pretreatment, pilot fermentation test and residual saccharides analysis. To study the impact of hyperbaric condition at bottom of the large fermentor on yeast fermentation, high pressure carbon dioxide (CO2) was adopted to simulate the situation. The results showed that the fermentation was prolonged with the increasing pressure. The pressure of CO2 had little impact on the ethanol yield which could reach 90% under the pressure below 0.3 MPa. The inhibition was combined by the high pressure and CO2. Under the high CO2 pressure, the extracellular and important intracellular enzyme activities were different from those under normal state. The changes under 0.1 MPa and 0.2 MPa were similar. The changes under 0.3 MPa were closer to those under 0.4 MPa. The application of thermotolerance yeast could solve the problem of the inconsistent temperature between fermentation and saccharificaton and fulfill the real simultaneous saccharification and fermentation. And it could reduce the cooling cost. A thermotolerance strain Y-H1 was isolated in our research. It gave high ethanol concentration of 10.7%(w/w)at 40 ℃ for 33 h. The ethanol yield efficiency was over 90%. At 40 ℃, the extracellular and important intracellular enzyme activities of Y-H1 showed the difference with normal state, which may indicate its physiological changes at the high temperature. Molasses is another feedstock for industrial ethanol production. By our ethanol-tolerance strain and the regulation reagents, the fermentation with high ethanol concentration was investigated. In fed-batch mode combined with cold acid deposition, the highest ethanol concentration was 10.26% (w/w) for 42h. The aldehyde concentration in fermentation was found to be related to ethanol concentration. The development of a rapid ethanol fermentation strain of Zymomonas mobilis is essential for reducing the cost of ethanol production and for the timely utilization of fresh material that is easily decayed in the Chinese bioethanol industry. A mutant Z. mobilis strain, 10232B, was generated by UV mutagenesis. Under these optimized conditions, fermentation of the mutant Z. mobilis 10232B strain was completed in just 18 h with a high ethanol production rate, at an average of 4.92 gL-1h-1 per batch. The final maximum ethanol concentration was 88.5 gL-1, with an ethanol yield efficiency of 93.6%. This result illustrated the potential use of the mutant Z. mobilis 10232B strain in rapid ethanol fermentation in order to help reduce the cost of industrial ethanol production. As fresh sweet potato syrup shows high viscosity, it is hard to be fully converted to glucose by enzymes in the traditional saccharification process. The high-viscosity syrup is difficult to be transmitted in pipes, which may be easily blocked. Meanwhile it could also reduce the later ethanol fermentation efficiency. To solve these problems, effects of the pretreatment conditions were investigated. The highest dextrose equivalent value of 99.3 and the lowest viscosity of 4.5×104 mPa.s were obtained by the most favorable pretreatment conditions, while those of 85.8 and over 1.0×105 mPa.s was produced by traditional treatment conditions. The pretreatment could also be applied on the material syrup without adding water. The later experiments showed that the pretreated syrup had no negative effect on the ethanol fermentation and exhibited lower viscosity. The fuel ethanol rapid production from fresh sweet potato was enlarged in the 500L pilot scale after its fulfillment on the laboratory level. The optimal ratio of material to water was 3 to 1 in 500L fermentor. With low-temperature-cooking (85 ℃) using SSF, the Saccharomyces cerevisiae was able to produce ethanol 97.44 g/kg for 37h, which reached 92% of theoretical yield. The average ethanol production rate was 4.06 g/kg/h. And the maximum viscosity of syrup reached 6×104mPa.s. The results showed its superiority over current industrial ethanol fermentation. The compositions of the residual saccharides in the ethanol fermentation by sweet potato and cassava were analyzed by high performance liquid chromatography coupled with evaporative light-scattering detector. The results showed that all the residual saccharides were oligosaccharides, mainly composed of glucose, xylose, galactose, arabinose and mannose. The glucose, galactose and mannose could be slowly hydrolyzed from oligosaccharides in syrup during a long period. To increase the glucoamylase dosage could lower the residual saccharides to a certain extent. However, excess glucoamylase dosage led to more residual saccharides. And the method of 3, 5-dinitrosalicylic acid could not accurately quantify the residual total saccharides content. Two residual saccharides degrading strains were isolated, which could utilize 40% of total residual saccharide and lower the syrup viscosity. With the analysis of morphology and internal transcribed spacer sequence, they were finally identified as species of Trichoderma and Aspergillus niger.