固定化假丝酵母脂肪酶催化合成辛酸甘油酯

以自制固定化假丝酵母脂肪酶作为催化剂,研究了无溶剂体系中辛酸和甘油直接酯化合成辛酸甘油酯的反应条件。考察了酶的种类、底物的物质的量之比、温度、酶量、甘油的初始含水量和反应时间等因素对辛酸转化率和产物组成的影响。结果证明,以纺织物作为载体制备的固定化假丝酵母脂肪酶适宜催化辛酸甘油酯的合成。最优反应条件为：辛酸与甘油的物质的量之比为2∶1,固定化假丝酵母脂肪酶加量为0.5g/0.69g甘油,温度为40 ℃,振荡培养箱转速为190 r/min。最优反应条件下辛酸转化率可以达到94%以上,经过简单处理的固定化酶可以重复使用4批。     

固定化脂肪酶催化废油合成生物柴油

研究了固定化假丝酵母99-125脂肪酶在有溶剂的体系下催化废油合成生物柴油过程中,油醇摩尔比、有机溶剂性质、底物浓度、体系含水量、甲醇流加等因素对反应过程的影响.研究结果表明,在最佳实验条件下,反应转化率最高可达92％,酶的使用寿命可达7批以上.     

乙醛对假丝酵母脂肪酶催化活性的影响

采用紫外可见分光光度法和荧光发射光谱法研究了乙醛溶液对假丝酵母脂肪酶水解三油酸甘油酯的催化活性和构象的影响。结果表明,低浓度乙醛能提高酶的催化水解活力,当乙醛浓度为0.221 5 mmol/L时,酶活力提高了18.84%;高浓度乙醛对酶活力有抑制作用,当乙醛浓度为3.322 5 mmol/L时,酶活力降低了25.85%。低浓度乙醛使酶催化反应的最适p H向碱性方向偏移,紫外吸收光谱和荧光发射光谱均有显著增强和光谱峰偏移现象。动力学分析表明,加入乙醛后,酶的V_(max)增大,K_m减小。     

响应面优化褶皱假丝酵母脂肪酶催化合成木质甾醇油酸酯

以木质甾醇转化率为指标,考察了10种常见商业化脂肪酶催化合成木质甾醇油酸酯的效果,确定褶皱假丝酵母脂肪酶(CRL)为优选生物催化剂,进一步筛选出正己烷为优选反应介质.在脂肪酶用量、油酸和木质甾醇的物质的量比、反应温度和反应时间这4个单因素考察基础上,通过响应面分析法对酶催化木质甾醇油酸酯合成工艺条件进行优化,并对优化条件进行验证和放大实验.CRL催化合成木质甾醇油酸酯的优化工艺参数为:CRL添加量为木质甾醇质量的10％,油酸与木质甾醇的物质的量比为3.8:1,反应温度为46℃,反应时间为28 h,木质甾醇的转化率为91.56％±0.25％.     

磁性壳聚糖纳米复合材料固定化褶皱假丝酵母脂肪酶催化合成木质甾醇酯

以磁性壳聚糖纳米复合材料共价固定的褶皱假丝酵母脂肪酶为催化剂,以木质甾醇和油酸为原料,对木质甾醇油酸酯的酶法合成工艺条件进行了优化。得到的最佳工艺条件为：催化剂用量12.7%（以底物总质量计）,油酸与木质甾醇物质的量比为2∶1,木质甾醇质量浓度为122.9 g/L,反应温度50℃,反应时间24 h。在该条件下,木质甾醇转化率为96.42%。对月桂酸、肉豆蔻酸、棕榈酸不同碳链长度的脂肪酸或混合脂肪酸进行酯化反应,木质甾醇的转化率可达96.67%～98.74%,催化剂使用5次时,转化率仍可达82.45%。     

固定化假丝酵母99-125脂肪酶催化酯化脂肪酸低碳醇酯反应条件的研究

以硅藻土和纺织品为载体 ,采用吸附法制备固定化脂肪酶 ,研究了固定化假丝酵母 99 1 2 5脂肪酶在有机溶剂中催化脂肪酸低碳醇酯酯化合成过程中 ,有机溶剂性质、脂肪酸与低碳醇的结构、pH值、反应温度和体系含水量、低碳醇的抑制作用等因素对酯化过程的影响。试验结果表明 :底物低碳醇需要采用流加方式加入体系 ,石油醚是最适宜的有机溶剂 ,脂肪酸与醇的碳链越长 ,越易于酯化 ;固定化脂肪酶对直链醇的选择性优于支链醇。以石油醚为有机溶剂 ,在反应温度为 40℃、pH值为 7时 ,硬脂酸与甲醇的酯化率达 95 % ;反应后期应除去体系中的水以避免酶失活。固定化酶间歇催化油酸与甲醇的酯化时 ,重复使用 1 5次 (每次 2 4h) ,其操作半衰期约为 360h。     

南极假丝酵母脂肪酶发酵条件优化及酶学性质

分别用摇瓶和15L发酵罐,对南极假丝酵母产胞外脂肪酶的培养基成分和操作条件进行了实验研究。得到最优的培养基组成为:豆粉40g／L,淀粉15g／L,豆油5mL／L,K2HPO4g／L,MgsO4·7H2O1g／L,Tween-800.1％,酵母膏5g／L;操作条件为:温度24℃,初始pH值为6.0,通气量为10.0L／min。在此培养条件下,发酵周期缩短至54h。由15L发酵罐生产的酶液酶活达到19.2U／mL。酶液在pH值为4.0～6.0和7.5～9.0范围内较稳定,其最适宜pH值范围为6～8.5;70℃时酶的催化活性最大.在40～70℃的温度范围内保持1h后残留酶活为60％。     

硫酸铵-丙酮协同沉淀法纯化南极假丝酵母产脂肪酶

采用硫酸铵-丙酮协同沉淀法,对南极假丝酵母产脂肪酶(CALB)进行了分离纯化研究.经正交实验确定纯化工艺为:向酶液中加入硫酸铵至饱和度45%的同时加入0.3倍酶液体积的丙酮;离心后再向上清液中加入硫酸铵至饱和度75%,分相后,相界面处沉淀即为脂肪酶粗品.经分离纯化后,酶活回收率为54%、纯化倍数为2.72.     

生物柴油合成中脂肪酶的应用研究进展

生物柴油是以动植物油脂为原料制造的可再生能源,可作为石油柴油的替代或部分替代燃料.生物柴油的发展不仅有利于解决能源问题,而且可以减少温室气体的排放量.本文对脂肪酶的催化活性和选择性,脂肪酶的固定化、不同反应体系中生物柴油的脂肪酶催化合成及其操作条件,不同酰基受体对脂肪酶催化制备生物柴油的影响等问题的研究进展进行了综述.     

用蛋白质工程技术提取和修饰南极假丝酵母脂肪酶B

从南极假丝酵母中提取的脂肪酶B,具有较高的对应异构体选择性,广泛应用在培养基中,作为不对称有机化学的生物催化剂。近年来,一系列组合蛋白质工程研究和扩展了南极假丝酵母脂肪酶的催化和物理特性。这些工程不但生产出了指定的催化剂,还有助于阐明酶的结构一作用关系,并且有助于说明这些酶的对应异构体选择性。进一步的研究将在工程与酶的关系方面展开讨论。     

固定化Candida sp.99-125脂肪酶催化大豆油合成脂肪酸乙酯

探讨了酶法合成脂肪酸乙酯作为生物柴油的可行性. 以大豆油和乙醇为原料,利用本实验室自制的固定化Candida sp. 99-125脂肪酶催化反应,深入研究水含量、溶剂量、脂肪酶量及反应温度等因素对酶法合成脂肪酸乙酯的影响. 结果表明,以大豆油质量为基准,在水含量为 12.5%(w)、溶剂正己烷为3 mL/g、脂肪酶量为20%(w)、温度40℃的优化反应条件下,3次流加乙醇,170 r/min摇瓶反应,12 h后可以达到96.8%的最高酯得率. 进一步研究表明,在此优化反应条件下,连续使用14批脂肪酶酯得率可保持70%以上.     

固定化Candida sp. 99-125脂肪酶催化合成蜡酯(英文)

Wax esters were synthesized in a solvent free system catalyzed by immobilized lipase from Candida sp. 99-125, with oleic acid and cetyl alcohol. The effects of substrate molar ratio, lipase dosage and water removal were investigated in a 50 ml flask incubated in a thermostatic cultivation cabinet. The optimized conditions were: temperature 40 ℃, shaking at 170 r·min-1, acid/alcohol molar ratio 1:0.9, lipase dosage in 10% (by mass) of oleic acid, and open reaction for water removal. As a result, the conversion rate reached 98% for reaction of 8 h. The volume of reactor was scaled up to 1 L three-neck flask. The optimized parameters were: 200 r·min-1 agitation speed, 2.5% (by mass) lipase dosage, others were the same as the parameters described above. The conversion rate reached 95% for reaction of 24 h. The lipase retained 46% conversion rate after reuse for 6, 7 batches. The products were purified by removing remained cetyl alcohol and fatty acids with ethanol and saturated sodium carbonate so-lution, respectively. The purity of the wax ester, cetyl oleate, was 96%. The physical and chemical properties of cetyl oleate were tested and compared with those of jojoba oil. The results show that the product cetyl oleate has great potential to use as the substitute of natural jojoba oil.     

Stability of Immobilized Candida sp. 99–125 Lipase for Biodiesel Production

The stability of the immobilized lipase from Candida sp. 99–125 during biodiesel production was investigated. The lipase was separately incubated in the presence of various reaction components such as soybean oil, oleic acid methyl ester, n‐hexane, water, methanol, and glycerol, or the lipase was stored at 60, 80, 100 and 120 °C. Thereafter the residual lipase activity was determined by methanolysis reaction. The results showed that the lipase was rather stable in the reaction media, except for methanol and glycerol. The stability study performed in a reciprocal shaker indicated that enzyme desorption from the immobilized lipase mainly contributed to the lipase inactivation in the water system. So the methanol and glycerol contents should be controlled more precisely to avoid lipase inactivation, and the immobilization method should be improved with regard to lipase desorption.     

Candida sp.99-125脂肪酶及其在化学品合成中的应用

传统的酯化或转酯化产品的合成通常需要高温、强酸、强碱等相对苛刻的条件,脂肪酶由于其生物催化过程具有高效、高选择性、条件温和和环境友好等特点,在化学品的合成中越来越受到人们的关注。本课题组开发了一种可以用于酯类合成的新脂肪酶,并且实现了该酶的工业化生产。来源于Candida sp. 99-125的脂肪酶在非水相中对酯化和转酯化反应具有高效的催化活性和稳定性。本文介绍了该脂肪酶的发酵生产及其在中长链脂肪酸酯、二元酸酯、维生素A棕榈酸酯、手性化合物以及生物柴油等多种化学品的合成中的应用。     

Acid-Catalyzed Homogeneous Esterification Reaction for Biodiesel Production from Palm Fatty Acids

This work deals with esterification of palm fatty acids to produce biodiesel in a batch reactor, using homogeneous acid catalysts, evaluating the effect of the alcohol used, presence of water, type and concentration of catalysts. Methanesulfonic and sulfuric acid were the best catalysts. Reaction with methanol showed greater yields. It was showed very clearly that the presence of water in the reaction medium showed a negative effect in the reaction velocity. Kinetic parameters were estimated and molecular modeling was performed. Protonation of the carboxylic moiety of the fatty acid were defined as rate determinant step for the reaction.     

固定化酶及全细胞生物催化合成生物柴油的研究进展

生物柴油是一种可再生的绿色环保型能源.酶法合成生物柴油具有条件温和、醇用量小、甘油易回收等优点.本文综述了固定化脂肪酶、全细胞生物催化剂在生物柴油制备中研究应用的新进展.     

Enzymatic production of fatty acid alkyl esters with a lipase preparation from Candida sp. 99‐125

A lipase preparation developed from Candida sp. 99‐125 was used for fatty acid alkyl ester synthesis by both enzymatic esterification of fatty acids, and transesterification of oils and fats. The lipase preparation was chosen based on screening of lipases from commercial sources as well as those produced in the laboratory. The effects of enzyme dosage, solvent types, water absorbent additions, inhibition of short‐chain alcohols, alcohol and acid types, molar ratio of substrates, and reusability of the lipase preparation in esterification were studied. Degree of esterification between oleic acid and methanol under optimal conditions reached 92%. Purity of the methyl ester after washing with water and distillation was 98%. Half‐life of the lipase preparation was calculated to be approximately 340 h. For transesterification of rapeseed oil with the same lipase preparation, the amount of methanol and mode of methanol addition to the reaction were also conducted. Transesterification of the oil with stepwise methanol addition reached 83% after 36 h reaction time.     

用固定化脂肪酶Candida sp．99-125由粗米糠油酶法合成脂肪酸甲酯

The non-edible crude rice bran oil was extracted from white rice bran, and then was catalyzed by immobilized lipase for biodiesel production in this study. The effects of water content, oil/methanol molar ratio, temperature, enzyme amount, solvent,number of methanol added times and two-step methanolysis by using Candida sp. 99-125 as catalyst were investigated. The optimal conditions for processing 1 g rice bran oil were: 0.2 g immobilized lipase, 2 ml n-hexane as solvent, 20% water based on the rice bran oil mass, temperature of 40 °C and two-step addition of methanol. As a result, the fatty acid methyl esters yield was 87.4%. The immobilized lipase was proved to be stable when it was used repeatedly for 7 cycles.     

一种酶法催化合成生物柴油的气相色谱快速测定法

研究了酶法制备生物柴油中各种脂肪甲酯的气相色谱快速定性定量测定方法.实验采用Agilent-INNOWAX毛细管色谱柱,以十七烷酸甲酯为内标,程序升温测定生物柴油中主要脂肪酸甲酯,建立了一种简单、快速、准确的方法.各种脂肪酸甲酯的回收率在97.53%～99.67%之间,标准偏差为0.001 1～0.008 5,变异系数为0.46%～1.60%(n=6).