壳聚糖对油茶炭疽病菌的抑制作用

研究了2种不同壳聚糖(水溶性壳聚糖CS1、酸溶性壳聚糖CS2)对油茶炭疽病菌的抑制作用.结果表明:这2种壳聚糖均对油茶炭疽病菌有明显的抑制作用,且随壳聚糖浓度的增大而抑菌活性增强;在pH 5.3~6.0环境中抑菌效果最优,最佳酸溶剂为酒石酸和醋酸;2.50 mg.mL-1CS1 1%HA c对油茶炭疽病菌抑制率为71.6%,抑制作用几乎与500倍甲基托布津等效.壳聚糖是甲壳素脱去乙酰基的产物,无毒无害,可生物降解,又具有较强抑菌作用,可望开发为一种新型的环保农药.     

壳聚糖复合水凝胶对水溶液中铜离子(Ⅱ)的高效吸附

以甲基丙烯酸(MAA)、丙烯酰胺(AM)和烯丙基磺酸钠(SAS)同时对壳聚糖进行接枝改性,合成了一系列对水溶液中的二价铜离子具有高效吸附性能的壳聚糖水凝胶。研究了吸附剂粒径、投料量、溶液pH值对吸附容量的影响,同时进行了对金属铜离子的吸附性能研究。结果显示,粒径0.074~0.2 mm的吸附剂,在25 mL铜离子(II)质量浓度4 000 mg/L,pH值6的硝酸铜溶液中,投入量为0.1 g时,壳聚糖复合水凝胶最大吸附量为823 mg/g,同时吸附容量随溶液pH值增加而增加,随投料量的增大而减小。吸附等温线研究表明,Freundlich吸附模型能更好地描述吸附剂对铜离子(II)的吸附行为,说明其吸附过程是不均匀的多分子层吸附过程。     

链霉菌Z18中一种木聚糖酶(XynA)的纯化和性质

研究了链霉菌Z18中一种低分子质量木聚糖酶(XynA)的纯化和性质.粗酶液经过20%～50%硫酸铵沉淀和S-300凝胶过滤两步纯化得到电泳纯的XynA,分子质量为22ku,最适pH值为7.0,pH值稳定范围在5.0～8.0之间;最适温度为60℃,稳定温度为50℃.XynA对不同木聚糖表现出较高的活力,对其它所试底物无活性.XynA水解桦木木聚糖的主要产物为木二糖和木三糖,无木糖生成,说明它适合应用于低聚木糖的生产.     

米根霉利用玉米芯渣同步糖化发酵联产富马酸和真菌壳聚糖

以碱处理玉米芯渣为原料,研究米根霉利用高质量浓度玉米芯渣同步糖化发酵(SSF)生产富马酸,同时从米根霉菌体中提取真菌壳聚糖。结果表明,高底物质量浓度纤维素酶水解提高了葡萄糖质量浓度,有利于米根霉发酵产富马酸。米根霉利用质量浓度为100 g/L的玉米芯渣SSF,发酵至72 h,富马酸质量浓度达到28.65g/L,是质量浓度为50 g/L玉米芯渣SSF中富马酸质量浓度的1.95倍。采用碱法从米根霉菌体中提取壳聚糖,米根霉壳聚糖脱乙酰度为90%;米根霉壳聚糖溶液(质量浓度为20 g/L)黏度为2 m Pa·s,米根霉壳聚糖的重均分子量和数均分子量分别2 578和1 532 u。本研究实现了米根霉以木质纤维原料为碳源联产富马酸和真菌壳聚糖,为木质纤维原料高值生物转化有机酸和生物高分子提供成本较低的新途径。     

酸、碱、盐胁迫下千层金幼苗的生理指标变化研究

以千层金实生苗为材料，采用盆栽模拟试验，研究不同浓度酸、碱、盐胁迫连续15天和30天对千层金幼苗的形态、叶片含水量、叶绿素含量、脯氨酸含量、丙二醛含量以及SOD活性的影响。结果表明，不同处理的植株与对照（ CK）相比，除了pH值为4和11条件下植株出现叶片枯萎脱落现象，叶片含水量呈下降趋势以外，其余的在形态上没有太大的变化，表明千层金幼苗对酸、碱胁迫有一定的抗性，在pH值为5～10浓度处理下的植株均能正常生长；随着胁迫时间的延长，叶绿素含量以pH值为8的居高，随着pH值的降低和升高，均呈现逐渐降低的趋势，而丙二醛含量、脯氨酸含量以及SOD活性均明显高于对照（ CK）；用不同浓度混合盐碱对千层金幼苗进行胁迫处理，随着浓度的增大，脯氨酸含量和SOD活性呈先升后降的趋势，丙二醛含量不断增加，当pH值大于9， NaCl浓度在0.3％以上的盐碱混合胁迫处理15天以后，千层金幼苗植株受伤害程度不断加大。     

木质素磺酸钙的络合性能研究

研究了木质素磺酸钙(简称木钙，CLS)的浓度、溶液中钙离子(Ca^2 )浓度及pH值等因素对其络合性能的影响。结果发现，单位质量木钙中络合的Ca^2 量随木钙浓度增加而增加。当溶液中外加Ca^2 浓度增加到一定程度或pH值升高时，木钙的络合能力提高。pH值11时，质量浓度为10g/L的木钙溶液对Ca^2 的络合能力比原溶液增大3．7倍。进一步研究了具有不同羟基、羧基和磺酸基含量的木钙对Ca^2 的络合能力。结果表明，分子中大量羟基的存在是木钙具有络合能力的主要原因。     

造纸黑液磺化改性及改性产物性能研究

采取了先提木质素再将木质素磺化的方案进行造纸黑液的磺化,由分段正交试验(先羟甲基化再磺化)确定最佳磺化工艺,制备出磺化木质素.利用红外光谱表征产物,并测定了产物的磺化度、净浆流动度和重均分子质量(Mw).最佳磺化工艺:酸析木质素4 g,水40 g,甲醛溶液5 g,pH值11,75℃下反应2h,再调pH值为7,加亚硫酸钠2 g于140℃下反应4h,所得磺化木质素的净浆流动度为232 mm.红外分析表明磺化木质素中引入了较多的磺酸基;磺化木质素的磺化度为0.821 mmol/g,Mw为22.97 ku,均优于市售木质素磺酸钠,从而导致水灰比值0.35时其净浆流动度亦优于同掺量下的木钠.     

两性壳聚糖的制备及产物结构表征

以脱乙酰度大于 90 % 的壳聚糖(CTS)为原料,异丙醇为溶剂,ω(NaOH) 40.0 % 的碱液为催化剂,氯乙酸为羧甲基化试剂,NaOH、CTS、氯乙酸的质量比为1.0:1.0:1.25、反应温度 50.0 ℃、反应时间 7.0 h 的条件下制备了羧甲基壳聚糖(CM-CTS);以3-氯-2-羟丙基三甲基氯化铵(CTA)为改性剂,NaOH、CM-CTS、CTA的质量比为1.0:2.0:3.0、反应温度 60.0 ℃、反应时间 10.0 h,制得CTA季铵化羧甲基壳聚糖(CTA-CMCTS).IR和1 H NMR的结果表明,CTA-CMCTS为一既有季铵基团又有羧甲基的两性壳聚糖衍生物.以CTA-CMCTS为絮凝剂处理含Cd2 或含Cr6 模拟废水时,Cd2 和Cr6 的最大絮凝去除率分别可达 99.7 % 和 94.4 %.     

酸、铝胁迫对马尾松种子萌发与芽苗生长的影响

以石英砂为基质,采用国际上通用的培养液配制方法,研究了酸、铝胁迫(各设5个处理)对马尾松种子萌发及芽苗生长过程的影响,结果表明:中强度的酸、铝胁迫对发芽势及种子萌发过程的影响不显著,而对芽苗根、茎长及根、茎、叶的干质量、鲜质量等生长指标具有明显的抑制作用;芽苗生长指标随pH值(5.5 ～3.0)的下降,先缓慢上升后下降,随铝离子浓度的增加呈下降趋势;pH值4.5 ～5.0时,芽苗生长最好;根受酸、铝胁迫影响最大,是反应最敏感的部位,茎、叶次之;根鲜、干质量占总量的比例随酸、铝胁迫的加剧先上升而后降低,茎、叶的鲜、干质量占总量的比例变化较小;当pH值低于4.5,铝离子浓度达到50 mg·L-1时,即可对马尾松芽苗的生长产生明显的抑制作用.     

米根霉废菌体制备壳聚糖及其成膜性能

以米根霉乳酸发酵废菌体制备壳聚糖,并对其成膜性能进行研究。结果表明,米根霉发酵100 g/L葡萄糖48 h,可获得51.59 g/L的乳酸和4.36 g/L的米根霉菌体,废菌体中可提取壳聚糖占菌体干质量的13.5%。米根霉菌体提取的壳聚糖脱乙酰度89.4%,高于商品壳聚糖的脱乙酰度86.6%。20 g/L的米根霉壳聚糖溶液黏度5.13 mP a·s,重均分子质量(68.61 ku)与螃蟹壳来源的商品壳聚糖重均分子质量(70.17 ku)相近,两者的红外光谱基本一致。厚度为(0.025±0.002)mm壳聚糖膜,米根霉壳聚糖膜和商品壳聚糖膜的弹性模量分别为42.72和14.64 N/mm2,拉伸强度分别为132.31和44.13 N/m,吸水率分别为52.90%和175.80%,最大失重速率温度分别为281.4和285.4℃,起始和终止分解温度存在差异。米根霉壳聚糖的成膜性能优于商品壳聚糖,适合于食品包装薄膜的制备。     

红豆杉多糖的提取与结构初探

红豆杉枝叶经热水浸提、浓缩、醇沉、透析等工序制得一种红豆杉多糖,采用SephadexG-100凝胶渗透法测定分子质量,采用气相色谱法测定其单糖组成,并测定了不同纯度红豆杉多糖的红外光谱。所得红豆杉多糖分子质量约为59.2 ku,可视为由约365个糖残基构成的高分子化合物,其单糖残基鼠李糖、阿拉伯糖、甘露糖、葡萄糖、半乳糖数量比约为4∶6∶1∶1∶4。该红豆杉多糖分子结构中含有普通单糖、糖醛酸或氨基酸残基等,单糖主要以吡喃环形式存在、通过β-(1,3)苷键结合形成一种糖蛋白缀合物,Sevag法处理不能完全除去分子中的肽链。     

华盖木多酚氧化酶酶学特性研究

以华盖木嫁接苗当年生茎段为试材提取PPO酶液,研究温度、pH值、底物邻苯二酚浓度及抑制物对PPO活性的影响。结果表明:华盖木多酚氧化酶的最适温度为35℃,最适pH值为7.0,温度和pH值过高或过低都会降低酶活性;邻苯二酚浓度为0.14 mo.lL-1时,PPO活性最大,低于0.14 mo.lL-1时,随底物浓度的增加,酶活性增加,超过0.14 mol.L-1时,加大底物浓度酶活性降低;Na2SO4、柠檬酸、抗坏血酸(Vc)对华盖木PPO的活性均有一定的抑制效果,其中Vc的抑制效果最显著。     

来源于解酯菌的嗜热耐碱脂肪酶的表达纯化及其酶学性质研究

脂肪酶广泛应用于食品加工、生物柴油制备等领域。为了有效提高微生物脂肪酶的可利用度,将来源于解酯嗜热菌(Thermosyntropha lipolytica DSM 11003)的脂肪酶基因(tll2)克隆到大肠杆菌表达载体pET28a中,获得重组质粒pET28a TLL2,将pET28a TLL2转入大肠杆菌BL21(DE3)宿主菌中进行高效表达。通过热处理和镍柱亲和层析得到电泳纯的蛋白TlLip2,对其进行酶学性质表征。结果显示,TlLip2的亚基分子质量为57 ku,比酶活为31 U/mg,最适反应pH及温度分别为8.0和60℃。在60℃以下、pH 6.0~11.0范围内,TlLip2的稳定性较好,相对酶活均维持在60%以上。金属离子K+和Na+对TlLip2有较大激活作用,而Co^2+、Zn^2+、SDS和Tween 80对TlLip2酶活力抑制作用明显。TlLip2在极性小的有机溶剂中具有较好的耐受性。TlLip2对中等碳链长度的对硝基苯酯显示出更高的活性,其中以对硝基苯己酯为底物时,TlLip2的酶活最高;以对硝基苯棕榈酸酯为底物时,该酶的动力学常数Km为0.29 mmol/L,Vmax为2.28 mmol/(L·min^-1),kcat为6.19 s^-1。此外,将其应用到油酸乙酯的合成研究中,以油酸和乙醇为底物,研究TlLip2催化制备油酸乙酯的转化条件,结果表明在60℃、加酶量为100 U/g的TlLip2,催化摩尔比为1∶2的油酸和乙醇,12 h后油酸乙酯的转化率达到62.1%,表明TlLip2在催化脂肪酸酯化方面具有较大的应用潜能。     

Evaluation of factors that have an influence on the fixation of chitosan in wood

When using chitosan as an antifungal agent in wood it is important to understand which factors contribute to a higher fixation ratio to optimize the utilization of chitosan, the active component. Small pine samples were impregnated with chitosan solutions varying in molecular weight, concentration, pH, polymerization agent, acid and degree of deacetylation. Different post-treatments such as time, temperature, moisture content and the effect of present air were applied to the samples to evaluate the effect on the relative retention. After impregnation, the samples, with a volume of 1.5 cm³, were leached in separate test-tubes according to EN-84. The samples were prepared in a paired design where both samples were impregnated, but only one was leached. Both leached and unleached samples were analysed for their chitosan content, and the relative ratio was used as a measure for the relative retention of chitosan during leaching. The results from these trials show that pH in the range of 5.1-5.9 is favourable. The molecular weight should be as high as possible yet able to penetrate the wood structure, and the use of acetic acid gives far better fixation than the use of hydrochloric acid.     

Anti-acne activity of tannin-related compounds isolated from Terminalia laxiflora

In our investigation to find out new anti-acne agent, we focused on Terminalia laxiflora Engl & Diels (Combretaceae) methanolic wood extract, which has been selected during previous screening experiments for anti-acne agents, which included 29 species of Sudanese medicinal plants. Based on the biologically guided fractionation using an antibacterial assay against Propionibacterium acnes, a lipase inhibitory assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay; five tannin-related compounds were isolated, such as ellagic acid, flavogallonic acid dilactone, terchebulin and gallic acid. Terchebulin showed good antibacterial activity; minimum inhibitory concentration (MIC) = 125 μg/ml and minimum bactericidal concentration (MBC) = 250 μg/ml. Gallic acid exhibited lipase inhibitory activity with IC₅₀ value of 149.3 μM, which showed strong inhibition compared with terchebulin, IC₅₀ 260.7 μM. However, all compounds exhibited better or equal DPPH radical scavenging activity to (+)-catechin as positive control. Ellagic acid and terchebulin showed the best DPPH radical scavenging activities, IC₅₀ 4.86 and 4.90 μM, respectively. This study demonstrated that terchebulin has potentiality as an anti-acne agent.     

Evaluation of factors that have an influence on the fixation of chitosan in wood

Abstract

When using chitosan as an antifungal agent in wood it is important to understand which factors contribute to a higher fixation ratio to optimize the utilization of chitosan, the active component. Small pine samples were impregnated with chitosan solutions varying in molecular weight, concentration, pH, polymerization agent, acid and degree of deacetylation. Different post-treatments such as time, temperature, moisture content and the effect of present air were applied to the samples to evaluate the effect on the relative retention. After impregnation, the samples, with a volume of 1.5 cm³, were leached in separate test-tubes according to EN-84. The samples were prepared in a paired design where both samples were impregnated, but only one was leached. Both leached and unleached samples were analysed for their chitosan content, and the relative ratio was used as a measure for the relative retention of chitosan during leaching. The results from these trials show that pH in the range of 5.1–5.9 is favourable. The molecular weight should be as high as possible yet able to penetrate the wood structure, and the use of acetic acid gives far better fixation than the use of hydrochloric acid.     

Water relations of red spruce seedlings treated with acid mist

Pressure-volume curves, day and night transpiration rates, needle drying curves, and shoot water potentials were determined for 2-year-old red spruce trees that had been exposed for three months to a range of acid mists (pH 2.5 to pH 5.0) containing equimolar (NH(4))(2)SO(4) and HNO(3). No effect of acid mist was observed on cuticular resistance or on the rates of day and night transpiration, although trees exposed to acid mist exhibited symptoms of mild water stress. Significant decreases in maximum turgor, the relative water content (RWC) associated with zero turgor, and bulk volumetric elastic modulus occurred as the pH of the mist decreased from 5.0 to 2.5. At all RWC values, there was an increase in solute potential as mist pH decreased. Shoot water potential declined with a decrease in pH of the mist.     

抗菌剂改性纤维素物料及其抗菌性能(Ⅰ)--抗菌剂吸附研究实验

对纤维素物与表面活性抗菌剂的吸附性能进行研究。抗菌剂系乙烯基吡咯烷酮与巴豆酸共聚物和二甲基苄基烷基氯化物的合成聚合物及其较低分子量的类聚物。确定纤维素物料对活性抗菌剂 可逆吸附作用，并且决定于初始溶液浓度。     

山胡椒叶片次生代谢产物抑菌活性大小分析

分别以甲醇、丙酮、水为提取剂,提取山胡椒叶片的次生代谢产物,并测定3种不同提取液的次生代谢产物含量及体外抑菌效果,评价山胡椒的药用价值,为山胡椒的进一步开发利用提供理论依据。实验结果表明,不同提取液中次生代谢产物含量均是黄酮>鞣质>游离蒽醌>皂甙>生物碱;3种提取液的次生代谢产物含量及抑菌活性存在较大差异,不同提取液对枯草芽孢杆菌的抑菌活性要高于大肠杆菌、水可作为山胡椒叶片次生代谢产物的良好提取剂。通径分析表明,影响不同提取液对枯草芽孢杆菌的抑菌活性的次生代谢产物主要是总黄酮和总皂甙,影响提取液对大肠杆菌抑菌活性的次生代谢产物主要是总皂甙。     

银杏枝条营养贮藏蛋白质的组分及动态变化

采用SDS-聚丙烯酰胺凝胶电泳技术和电子显微镜技术,对银杏枝条营养贮藏蛋白质组分及其动态变化规律进行研究.结果表明:银杏营养贮藏蛋白质主要存在于枝条的树皮和木质部中;当年生枝条含量高于2年生枝条,树皮的含量高于木质部;枝条中营养贮藏蛋白质组分主要是分子质量为36 ku和32 ku的蛋白质;银杏营养贮藏蛋白质的动态变化分为积累和降解2个阶段,5月中旬新叶形成后即开始积累,12月份达到最高,翌年春季降解满足芽的萌发,至4月上旬逐渐消失.