纤维素酶活力测定条件研究

用DNS法测定纤维素酶活力,分析测定条件对测定结果的影响。在不同的条件下测定酶活力会得到不同的纤维素酶活力测定值。其中,酶液用量、酶解反应时间、温度对测定结果影响较大,酶液的稀释度、DNS显色时间对测定结果也有一定影响。测定纤维素酶活力的最适条件为:酶解反应时间为30min,最适温度40℃,DNS用量2.5ml,显色时间5min。     

纤维素酶酶解小麦麸皮技术初步研究

本实验采用还原糖法研究了不同酶解时间、温度、pH值及酶浓度条件对纤维素酶酶解小麦麸皮效果的影响。结果表明,纤维素酶酶解小麦麸皮的最适条件为:酶解时间15min,温度37℃,pH值6,最适酶浓度0.04IU/mL。     

牛粪中温厌氧发酵高效处理工艺的研究

本试验研究了牛粪中温厌氧发酵工艺,探索牛粪中温厌氧发酵的高效条件,以达到高产气量的目的。试验采用自主设计的批量恒温发酵装置,在相同发酵浓度、同等体积及相同温度的条件下,通过测定COD、产气量和细菌总数研究了不同方法处理污泥、添加纤维素酶和不同接种时间对发酵效果的影响。结果表明,在加纤维素驯化污泥、添加纤维素酶及18d接种条件下,沼气产量有所提高。     

响应面法优化纤维素酶提取黄粱木叶蛋白工艺

试验旨在研究在纤维素酶活性范围内,使用纤维素酶提取黄粱木叶片叶蛋白的最适工艺。试验选用华南农业大学校园内黄粱木新鲜叶片,在不同温度、pH值、纤维素酶浓度处理下,提取叶片中叶蛋白并测定其蛋白含量,运用响应面分析法优化纤维素酶提取黄粱木叶蛋白工艺。结果表明,温度、纤维素酶浓度对叶蛋白提取率无显著影响(P0.05),pH值对叶蛋白提取率影响显著(P0.05),最优提取工艺为纤维素酶浓度为11.93 U/g,温度为50℃,pH值为4,提取率达29.88%。在保证纤维素酶活性的条件下,可通过该工艺最大程度提取黄粱木叶片中的蛋白质。     

苹果渣生产饲用酶培养基优化的研究

为了优化苹果渣培养基配方,试验采用碱性过氧化氢法对苹果渣进行处理,通过正交试验确定处理苹果渣的过氧化氢浓度、溶液p H值、提取时间和提取温度,从而得出最佳处理条件,以处理后的苹果渣为碳源进行发酵产酶,通过与常用碳源比较优化培养基配方,在适宜的条件下进行木霉菌种培养,采用DNS法测定了纤维素酶活力。结果表明:过氧化氢浓度为2.0%、溶液p H值为12.0、提取时间6 h和提取温度50℃处理效果最好;确定预处理苹果渣、麦麸之比为4∶3时产酶酶活力最高。     

PEG渗调处理改善高冰草种子活力的研究

以不同活力的高冰草种子为材料，研究了在15℃渗调温度下PEG不同处理浓度、不同处理时间对种子活力的影响。结果表明，PEG渗透处理自然贮藏8年活力降低的高冰草种子效果显著，发芽速度明显提高，种苗质量得到改善，在PEG处理浓度10％、处理时间24h和48h时效果最好。     

高产纤维素酶菌株的微波诱变及筛选研究

为了能够选育出一株高产纤维素酶的优良菌株,采用微波对其孢子悬液进行不同时间的辐照处理后,筛选出一株能高产纤维素酶的突变菌株B40 1,在最适产酶条件下,该突变菌株所产纤维素酶的滤纸酶活力和羧甲基纤维素酶活力分别是出发菌株的169.9%、110.0%。     

纤维素酶辅助提取金樱子总黄酮单因素试验

为优化纤维素酶辅助提取金樱子总黄酮的提取工艺,通过单因素试验考察乙醇浓度、液料比、提取时间、纤维素酶用量、p H值、提取次数等6个因素对金樱子总黄酮得率的影响,结果其最佳提取工艺条件为:乙醇浓度40%、液料比30∶1、提取时间120 min、纤维素酶用量1.0%、p H值6、提取温度60℃、提取2次,在该提取条件下,金樱子总黄酮得率为(79.30±1.59)mg/g。提示纤维素酶辅助提取金樱子总黄酮可行、得率较高。     

应用响应面试验设计优化酶法提取桑叶中1-脱氧野尻霉素的工艺条件

桑叶中富含的1-脱氧野尻霉素(1-deoxynojirimycin,DNJ)为一种哌啶类生物碱,是α-葡萄糖苷酶的强抑制剂,具有降低餐后血糖、抑制肿瘤转移和抗病毒等作用。应用纤维素酶法提取桑叶中的DNJ,在单因素试验考察纤维素酶的质量浓度、提取液p H值、提取温度、提取时间、料液质量浓度等5个因素对桑叶DNJ提取率影响的基础上,通过响应面法进一步优化得到的最佳提取工艺条件为:提取温度60℃,提取液p H值3.8,料液质量浓度0.017 0 g/m L,纤维素酶质量浓度3.4 mg/m L,提取时间1.0 h。用高效液相色谱测定在此优化工艺条件下桑叶DNJ的提取率为0.095 0%。与传统的水、酸提取桑叶DNJ的方法相比,采用该优化的酶法提取工艺条件桑叶DNJ的提取率显著提高(P0.01),比盐酸提取法提高了20.3%。     

饲用纤维素酶热稳定性的研究

对不同热处理参数(温度70￣100℃、时间30￣150s)条件下纤维素酶的活性进行了测定,结果表明:纤维素酶的活性损失率随处理温度的升高和时间的延长而增大。不同处理温度,酶活性损失率差异极显著(P<0.01);不同处理时间,酶活性损失率差异显著(P<0.05)。     

纳米二氧化钛-丝素复合膜的溶解性初探

研究了纳米二氧化钛在丝素溶液中的分散性 ,制备了不同配比的纳米二氧化钛—丝素复合膜 ,并对复合膜和纯丝素膜的溶解性能进行了初探。发现复合膜的溶失率比纯丝素膜的溶失率有所下降 ,认为添加二氧化钛纳米粒子的丝素可用于纤维、织物的功能性整理     

Ultraviolet light and mating behaviour in domestic broiler breeders

1. The perception of UVA light (320 < lambda < 400 nm) by domestic fowl may be an adaptation to naturally lit habitats and may still be functional in farmed varieties, although not utilised owing to the absence of these wavelengths in commercial house lighting. One function may be the mediation of sexually related signalling or communication. 2. In experiment 1, two groups of 41 adult broiler breeders (four cockerels, 37 hens) were kept under conventional fluorescent light, with or without fluorescent UVA supplementation amounting to 16.9% of the total spectral power output of the luminaires. Each light environment was approximately iso-illuminant as perceived by the birds. The two groups were exposed to the light environments alternately for five 2-day periods in a cross-over design. Mating behaviour, production measures and time budgets were recorded on the second day of each period. 3. A UVA-enriched environment increased the number of attempted matings (1.27 vs 0.99 matings/cockerel.h) and locomotion (5.3 vs 3.7 min/bird.hour). 4. In a second experiment, 10 hens were allowed to choose between four cockerels lit under different power levels of UVA (1.6%, 14.6%, 43.5%, 57.5% of the total spectral power output of the luminaires) in a four-armed maze. Again, each light environment was approximately iso-illuminant as perceived by the birds. Each hen was allowed to make one choice per day over four days, with the position of the cockerels and the UVA levels interchanged each day. This schedule was repeated with the same hens for two other groups of four cockerels. 5. At a distance of no less than 60 cm from the cockerel, the hens spent most time inspecting whichever cockerel was lit by 1.6% or 14.6% UVA (1.33 vs 1.37 vs 1.22 vs 1.16 log seconds/hen.choice, respectively for increasing UVA level). Similarly, when allowed to approach closer to the cockerels, the hens spent most time in the arm which contained a cockerel lit by 14.6% UVA light, (1.62 vs 1.88 vs 1.69 vs 1.51 log s/hen.choice, respectively for increasing UVA level). 6. UVA is clearly implicated in the transmission of sexual signals or communication which may have implications for the welfare and production of broiler breeders.     

底物和酶液稀释对黑曲霉纤维素酶活性测定的影响

本文采用DNS法测定黑曲霉纤维素酶活性,研究了底物羧甲基纤维素钠(CMC-Na)来源、浓度、纤维素酶浓度和酶液稀释效应对纤维素酶活性测定的影响。结果表明:以Signna产C5678为底物,纤维素酶活性测定值明显高于上海产的CMC,且C5678浓度≥3％后,其浓度对纤维素酶活性测定值无显著影响;纤维素酶浓度控制在吸光度0．1-0．4,反应进程曲线的线性较好,过高使得曲线下斜;另外,按传统公式计算纤维素酶活性,稀释倍数F越大,酶活性值也越高,使得测定值间缺乏可比性。研究发现将稀释倍数F校正为F0.82后,计算得出的纤维素酶活性值几乎不受稀释倍数影响。     

华北驼绒藜青贮贮藏过程中发酵品质的动态变化

本研究探讨了华北驼绒藜青贮过程中发酵品质动态变化及添加剂对其影响。试验处理设对照组、乳酸菌处理组、纤维素酶处理组和乳酸菌+纤维素酶混合处理组,分别在贮藏后的1,3,5,10,30和45 d后开封,测定其pH值、乳酸、乙酸、丁酸和氨态氮含量。结果表明,发酵最初3~5 d内pH值迅速下降;发酵最初10 d内乳酸和乙酸含量迅速增加;而随着贮藏时间延长氨态氮、丁酸含量逐渐增加。与对照组相比,添加乳酸菌制剂、纤维素酶和乳酸菌制剂+纤维素酶的3个处理组均可提高华北驼绒藜青贮料的乳酸含量,降低pH值、氨态氮、丁酸含量,改善华北驼绒藜青贮料的发酵品质;其中添加乳酸菌制剂+纤维素酶效果最明显。     

The effect of erythrosin B on infective larvae of bovine gastrointestinal nematodes

The effect of erythrosin B and visible light on 3rd stage larvae of gastrointestinal nematodes of naturally-infected cattle was studied. Cattle were treated orally with erythrosin B at dosages of 30 and 40 mg kg-1 day-1 for as many as 17 days. Feces from treated and untreated animals were collected and prepared for culture. Third stage larvae were then collected by Baermannization and exposed to light. Both sunlight and artificial fluorescent light were shown to be toxic to 3rd-stage-larvae after treatment with erythrosin B. This toxic reaction was significant after only 2 consecutive daily treatments.     

2个枯草芽孢杆菌源纤维素酶基因的克隆、融合表达及其酶学性质分析

本试验旨在构建不同纤维素酶的融合表达系统及探讨融合纤维素酶的酶学性质。利用PCR技术从实验室前期分离的枯草芽孢杆菌中分别扩增2个纤维素酶基因Cel42和Cel22,设计一段柔性接头(GSGGGS),通过酶切连接将2个纤维素酶基因构建在一个开放阅读框(ORF)内,插入到pET32a(+)中构建重组表达载体pET32a(+)-Cel42-Cel22,转化大肠杆菌BL21(DE3)进行诱导表达,并对其酶学性质进行研究。结果表明:本试验成功克隆了2个纤维素酶基因Cel42和Cel22,并构建了重组表达系统BL21(DE3)/pET32a(+)-Cel42-Cel22,十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)估计其分子质量约为101 ku,粗酶液中葡聚糖内切酶活性为57.62 U/mL,葡聚糖外切酶活性为32.57 U/mL。试验所得融合纤维素酶Cel42-Cel22的最适反应温度为50℃,最适反应pH为6.0,温度在30~70℃范围内时可维持70%以上的纤维素酶活性,pH在4.0~9.0范围内时可保持75%以上的纤维素酶活性,除Mn~(2+)外的其他金属离子对纤维素酶的活性均具有一定的抑制作用,其中Hg~(2+)和Cu~(2+)对的抑制作用较明显。由此可见,本试验在大肠杆菌BL21(DE3)中成功表达出了融合纤维素酶Cel42-Cel22,且该酶具有一定的活性,可适应较宽广的温度和pH范围,对金属离子敏感。     

一株高产内切纤维素酶贝莱斯芽孢杆菌的产酶条件优化及酶学性质分析

试验旨在对一株杜仲树皮内生菌贝莱斯芽孢杆菌(Bacillus velezensis)的内切纤维素酶(CMCase)进行产酶条件优化及酶学性质分析,为探究贝莱斯芽孢杆菌CMCase的相关特性提供参考依据。采用单因子试验设计,分别优化pH、接种量、温度、时间、碳源和氮源等发酵条件,并探讨温度、pH、底物专一性、金属离子及表面活性剂对CMCase的影响。结果表明,以玉米秸秆为碳源(30 g/L)、豆粕为氮源(30 g/L)、3%接菌量、pH 7.0的条件下37℃培养48 h,贝莱斯芽孢杆菌157的CMCase最高可达(5.14±0.18) U/mL。经CMCase酶学性质分析发现,贝莱斯芽孢杆菌157的最适酶反应温度为60℃,最适pH为5.0;温度稳定性试验发现,在40和50℃时,相对剩余酶活力均高于80%,随着温度的升高,酶活力逐渐降低,当温度高于55℃,相对剩余酶活力约为50%;pH稳定性试验发现,在pH 5.0～10.0之间耐受性良好,相对剩余酶活力均高于90%,随作用时间的延长,相对剩余酶活力变化不大。贝莱斯芽孢杆菌157 CMCase属于典型内切型纤维素酶。Na^+、Mg²⁺、Ca²⁺可促进贝莱斯芽孢杆菌157 CMCase酶活力,而Co²⁺、Hg²⁺、Fe²⁺、Cu²⁺和SDS抑制CMCase酶活力;表面活性剂Tween-80、Tween-20、Triton X-100对贝莱斯芽孢杆菌157 CMCase无影响。本试验通过对贝莱斯芽孢杆菌157进行产酶条件优化及CMCase酶学性质分析发现,贝莱斯芽孢杆菌157 CMCase具有产酶量高,耐受pH范围广的特点,在饲料添加剂、洗涤剂和造纸领域中具有一定的应用价值。     

Screening and Identification of the Cellulase-producing Fungus

In order to isolate the strains which could degrade fiber from the straw,the straw samples were inoculated on the potato agar medium and cultured at room temperature.The isolating strains were inoculated on the cellulose-congo red agar medium,the strains were screened that could produce bigger cellulose-decomposing zone.It was identified by morphological characteristics and molecular biological methods,and characterization of cellulase was analyzed preliminarily.The results showed that the fungus was Aspergillus niger,it could grow at room temperature,and the H/C was 7.64.The highest cellulase activity reached 42.18 U/mL when cultivated at 20 ℃ for 5 days.The optimum pH was 7.0 and the optimum reaction temperature was 20 ℃,the relative cellulase activity still retained above 90% at 20 to 40 ℃ or pH 6.0 to 8.0 for 1 h.The Aspergillus niger was a cold-adapted cellulaseproducing strain,it had strongger producing cellulase ability,and was tremendous potential valuable for microbial development.     

产纤维素酶真菌的筛选与鉴定

为从秸秆中分离出能够降解纤维的菌株,试验采取秸秆样品接种马铃薯琼脂培养基,在室温环境下培养,取分离菌接种纤维素刚果红琼脂培养基,筛选能形成较大降解圈的细菌,并进行形态学和分子生物学鉴定,测定其纤维素酶性质。结果表明,经分子生物学鉴定,筛选菌为黑曲霉菌,该菌在室温环境能够生长,菌株降解圈直径(H)与菌落直径(C)的比值(H/C)为7.64。筛选菌在20 ℃环境下培养5 d酶活达到最高值,为42.18 U/mL。纤维素酶最适pH为7.0,最适反应温度为20 ℃,在20~40 ℃或pH 6.0~8.0环境下作用1 h,相对酶活力仍保持在90%以上。综上所述,本试验分离的黑曲霉菌株是低温产纤维素酶菌株,产酶能力较强,具有潜在的开发价值。