共查询到20条相似文献,搜索用时 187 毫秒
1.
2.
糖酯是应用广泛的无毒非离子表面活性剂。相比于传统化学合成方法,酶催化合成糖酯具有众多优点,非常适合于食品添加剂的生产。酶催化合成糖酯的研究主要集中在酶的筛选,反应介质,反应底物,反应条件等方面。本文主要对近年来酶催化合成糖酯研究进展进行论述,并讨论了其中的问题和发展方向。 相似文献
3.
4.
5.
重要的原料药—辅酶Q10 总被引:15,自引:0,他引:15
赵美法 《精细与专用化学品》2001,9(22):6-8
辅酶Q10的合成方法有4种生物提取法、微生物发酵法、半化学合成法、化学合成法,其中微生物发酵法是近几年国内外开发的热点,被认为是较有前途的合成工艺.日本是最主要的辅酶Q10生产国,据统计,全球90%的辅酶Q10来自日本,日清制粉和协和发酵工业公司是产量最高的两家公司.我国目前采用生物提取法生产辅酶Q10总生产能力约为600kg/a,而2000年我国几个主要海关辅酶Q10的进口量就达14689kg,出口量为1278kg,市场缺口较大.我国茄呢醇生产能力接近100t/a(折百),应充分利用原料资源优势,攻克半合成法生产辅酶Q10的难关. 相似文献
6.
1,4-苯并二氧六环类木脂素因其独特的杀虫、保肝、抗氧化、抗肿瘤等生理活性在农业及医药行业具有广阔的应用前景。目前1,4-苯并二氧六环合成方法主要包括生物偶联法、仿生偶联法及化学合成法,本文从合成工艺、对映选择性及反应机理等方面进行了系统性探讨。生物偶联法过程中的非酶催化步骤导致产物多为立体和区域选择性的异构体混合物;仿生偶联法通过选择不同的取代基和氧化偶联剂以较高的产率获得单一对映产物;化学合成法通过选择不同的催化剂、氧化偶联剂及合成路线实现了1,4-苯并二氧六环的高效合成,尤其是在过渡金属催化下,能够高选择性地合成1,4-苯并二氧六环,这类反应已开展深入研究。 相似文献
7.
8.
王贤贤 《化学工业与工程技术》2011,32(2):43-47
介绍了化学酯交换法、酶催化法、全细胞催化法等生产生物柴油的方法。指出了这一领域难以实现商业化的原因,并针对这些问题提出了相应的建议,分析了生物柴油的现状及发展趋势。 相似文献
9.
10.
异麦芽酮糖是近年来新兴的一种功能性甜味剂,在食品、医药等工业中具有广阔的应用前景。蔗糖异构酶是生物法工业化生产异麦芽酮糖最有效的酶。本文介绍了近年来国内外蔗糖异构酶的生产菌株、酶学性质、结构与功能,阐述了蔗糖异构酶催化生产异麦芽酮糖和海藻酮糖的机制及其在异麦芽酮糖生产中的应用。并展望了其今后的研究方向:应从SIase高产菌株的选育、发酵产酶工艺优化方面开展工作,大幅度提高产酶水平。 相似文献
11.
木质纤维素转化为燃料乙醇的研究进展 总被引:26,自引:0,他引:26
以木质纤维素为原料生产燃料乙醇的生物转化方法包括预处理、酶水解和发酵过程,对这些过程中的技术进展以及解决现存问题的方法进行了评述。氨法爆破技术是较好的预处理方法,超声波、微波处理等新技术有助于改善酶水解。阐述了酶水解机理、纤维素酶的生产以及酶水解过程的优化方法。指出固定化酶糖化发酵技术在生物转化木质纤维原料技术中的前景广阔;选择合适的发酵方法,优化发酵过程,以及解决抑制问题对于提高乙醇产率尤为重要;利用基因重组技术构建旨在发酵混合糖的重组菌对于生产生物乙醇具有里程碑意义。 相似文献
12.
13.
Tween80对稻草水解及同步糖化与发酵产乳酸的影响 总被引:2,自引:0,他引:2
在生物转化纤维原料产乳酸的过程中,酶解纤维原料产还原糖是限速步骤。为了获得较高的产物产率,需较高的酶用量,这使大规模酶解废弃纤维原料的成本很高。对吐温80在酶解稻草纤维素产糖,以及耐高温乳酸菌同步糖化发酵稻草产乳酸过程中的作用进行了考察。初步结果表明,吐温80加入可使保持同等程度的水解率所需的酶用量降低,添加0.2 g/g底物的吐温80到酶用量10 FPU/g体系,水解120 h的糖产率为292.2 mg/g,比不加表面活性剂体系的糖产率增加了11%;添加0.7 g/L的吐温80进行同步糖化与发酵72 h,能使乳酸产量提高24.2%。 相似文献
14.
Evangelos Topakas Paul Christakopoulos 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(5):629-634
BACKGROUND: The high crystallinity of cellulose underlies the recalcitrance that this polymer presents in enzymatic degradation. Thus, a pre‐treatment step is applied in most bioconversion processes. Treatments with ionic liquids are considered an emerging pre‐treatment technology, owing to their high efficiency in solvating cellulose, over molecular solvent systems. RESULTS: Crystalline cellulose with and without ionic liquid (1‐ethyl‐3‐methylimidazolium acetate) treatment, both commercially available, were used as substrates in enzymatic hydrolysis reactions using the earlier evaluated cellulolytic system of Fusarium oxysporum. The in situ removal of the hydrolysate during reactions enhanced the reaction rate as well as the overall glucose production. Ionic liquid treatment significantly decreased cellulose crystallinity and enhanced bioconversion yields and rates. The effects of cellulose structural changes during treatment on hydrolysis rate were investigated and the recalcitrance constants were determined. CONCLUSION: The study showed that ionic liquid‐treated cellulose became more homogeneous and more easily degradable than the untreated cellulose, a conclusion that was expressed mathematically by the difference in the recalcitrance constants for the two substrates. It was concluded that glucose production from ionic liquid‐treated cellulose could achieve very high conversion yields in consolidated bioprocesses or during simultaneous saccharification and fermentation. Copyright © 2012 Society of Chemical Industry 相似文献
15.
Beatriz Palmarola‐Adrados Mats Galbe Guido Zacchi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):85-91
This paper reports on the optimization of steam pretreatment of barley husk for high pentose and hexose recovery in the subsequent enzymatic hydrolysis step, as well as high ethanol yield, following simultaneous saccharification and fermentation. The parameters optimized in the steam pretreatment step were residence time (5–15 min), temperature (190–215 °C), and concentration of the acid catalyst (0 or 0.5% H2SO4). A microwave oven was employed for screening of the optimal conditions to obtain the highest sugar yield following combined pretreatment and enzymatic hydrolysis. The final optimization of the pretreatment prior to enzymatic hydrolysis was performed on a larger scale, in a steam pretreatment unit. Simultaneous saccharification and fermentation was carried out following steam pretreatment on 5 and 10% dry matter steam‐pretreated slurries. Fermentability tests were performed to determine the effect of by‐products (ie furfural and 5‐hydroxymethyl furfural) in the bioconversion of glucose to ethanol by baker's yeast. The maximum glucose yield, 88% of the theoretical, was obtained following steam pretreatment with 0.5% H2SO4 at 200 °C for 10 min. Under these conditions, a sugar to ethanol conversion of 81% was attained in simultaneous saccharification and fermentation. Copyright © 2004 Society of Chemical Industry 相似文献
16.
Andrés Aguirre Matías Cabruja Rodolfo Cabrera Florencia Eberhardt Salvador Peirú Hugo G. Menzella Rodolfo M. Rasia 《Journal of the American Oil Chemists' Society》2015,92(1):47-53
Steryl glucosides (SG) are common contaminants in biodiesel that form precipitates, which form and cause problems due to fouling during transport and storage. Therefore, their quantification is necessary to assess the quality of this fuel. The methods currently available for SG analysis require expensive instrumentation, need a previous concentration step by solid‐phase extraction (SPE) or are of limited use for the quantitative assessment. We developed an enzymatic method for SG quantification in biodiesel samples based on the hydrolysis of the glucoside catalyzed by a broadly specific beta glucosidase and the subsequent determination of the glucose released by the reaction. The method is non‐expensive, sensitive and was adapted to 96‐well format fluorescence plate reader, making it useful for the parallel assay of multiple samples. The enzymatic assay presented here represent a valuable tool for both quality control and the development of improved biodiesel production and purification procedures. 相似文献
17.
18.
木质纤维素生物质是储量丰富的可再生资源,在能源、化工及医药领域具有广阔的应用前景。木质纤维素各组分因氢键和共价键的存在而结合紧密,需经酸、碱、高温、有机溶剂等预处理后才能高效酶解利用,其水解产物的主要成分为己糖(60%~70%,葡萄糖为主)和戊糖(30%~40%,木糖为主)的混合物。本文主要针对水解液中木糖和葡萄糖的共利用效率相关问题,以基因工程改造微生物利用木糖和葡萄糖共发酵生产醇类、生物油脂、γ-聚谷氨酸及有机酸等生物基化学品为主线,从代谢途径重构、基因水平调控及发酵技术优化等方面综述了近年来的研究进展。最后,从菌株筛选、基因与代谢工程调控、细胞固定化、产物处理及发酵工艺等层面总结了该领域目前的研究特点、技术瓶颈和未来的研究方向与思路。 相似文献
19.
玉米秸秆半纤维素制备木糖醇的研究 总被引:5,自引:1,他引:4
首先采用无污染的碱性过氧化氢法研究了半纤维素的分离与提取,然后对提取的半纤维素分别进行化学水解和酶水解比较,最后研究了水解液发酵制备木糖醇。结果表明,半纤维素分离提取的优化参数为:2%过氧化氢,2%氢氧化钠,加热时间4 h,反应温度75℃。使用CF3COOH水解半纤维素所得木糖含量为67%~73%,水解率为76%~84%,稀盐酸预处理半纤维素再化学水解所得木糖含量高达88%,水解率上升至大约90%。半纤维素的酶水解实验表明,木聚糖酶的水解专一性高于半纤维素酶,木聚糖酶水解率为38%~60%。在水解液发酵实验中,酶水解液的木糖醇转化率高于化学水解液。另外,通过浓缩半纤维素水解液,提高发酵液的木糖初始浓度,有利于菌株生长,可以提高木糖醇转化率。研究对于玉米秸秆半纤维素制备化学品具有一定的指导意义。 相似文献