假丝酵母菌GXU08产脂肪酶发酵条件的优化

以假丝酵母菌GXU08产脂肪酶催化合成麝香类香料—环十五内酯目前已备受关注,在一定条件下,环十五内酯的转化率与脂肪酶的水解酶活有直接关系,酶活越高其催化合成环十五内酯的能力越强。通过单因素试验和正交试验,对假丝酵母菌GXU08产脂肪酶的发酵条件进行优化。结果表明:最佳发酵培养基配方为蔗糖0.5%,淀粉0.5%,蛋白胨1.5%,K_2HPO_40.05%,MgSO_40.15%,(NH_4)_2SO_41%,茶油1.5%,菜籽油1.5%,pH=8,此培养基在28℃,180 r/min的条件下发酵培养48h,脂肪酶水解活力达到27.53 U/mL,是初始发酵培养基条件下所得脂肪酶酶活的3.74倍;其环十五内酯的转化率为16.6%,是优化前的4倍。     

聚氨酯泡沫固定产脂肪酶粗状假丝酵母(Candida valida T2)细胞的研究

对聚氨酯泡沫固定产脂肪酶粗状假丝酵母(Candida valida T2)细胞的固定化条件进行了研究.实验结果表明,聚氨酯泡沫颗粒经密度和粒径筛选,酸碱处理,以及固液比优化,载体固定细胞干质量比达到1571 mg/g,细胞脂肪酶的酶活为每克干细胞1415 U.电镜图片显示粗状假丝酵母菌(Candida valida T2)在载体孔隙内和脊壁上缠绕充盈,生长良好,固定结构稳定.固定化细胞连续催化水解桐籽油5批次,细胞相对水解酶活保持率达73%,固定细胞的损失率为12.5%.固定化细胞颗粒显示出良好的操作稳定性和酶活保持率,为进一步的应用研究提供了实验基础.     

脂肪酶产生菌Candida rugosa产酶条件研究

脂肪酶(Lipase,EC3.1.1.3)是用来催化酯类化合物的分解、合成和酯交换的特殊酶,具有高度的化学选择性和立体异构性,它广泛应用于食品、轻纺、皮革、香料、化妆品、洗涤剂、有机合成、医药等领域.本世纪80年代,美国科学家发现酶在近无水的有机溶剂中不仅能保存其催化活力,而且还获得许多新的催化特征[1],此后,脂肪酶在非水相酶催化领域的研究和应用逐渐增多.     

假丝酵母99-125脂肪酶的发酵工艺研究

对假丝酵母99-125脂肪酶的发酵工艺条件进行了一系列研究。选择了合适的培养基成分并进行优化 ,获得了最优的摇瓶培养基配方 (% ,W/V) :豆油 4.0 ,全脂豆粉 4.0 ,K₂HPO₄0.1,KH₂PO₄ 0.1。产酶水平能达到 5000IU/mL。在 30L发酵罐上进行初步放大实验 ,其产酶水平能达到 8100IU/mL。在1m³发酵罐上进行中试放大 ,产酶水平可达到 8000IU/mL。     

产朊假丝酵母(Candida utilis)基因工程研究进展

产朊假丝酵母是生物安全(Generally Recognized as Safe,GRAS)的微生物,也是一种重要的工业微生物。近20年来,随着分子生物学技术的发展,产朊假丝酵母的基因表达系统和基因工程研究及开发应用取得了显著的进展,使得利用该菌表达多种物质成为可能。本文概述了产朊假丝酵母的生物学特点、外源基因表达系统、基因敲除、遗传转化等方面的研究和应用进展。     

南极假丝酵母脂肪酶B基因在大肠杆菌中的表达和发酵优化

旨在利用大肠杆菌实现南极假丝酵母脂肪酶B(CALB)基因的高效可溶性表达,并降低生产成本.构建带有不同信号肽的CALB基因表达质粒,转化至不同大肠杆菌宿主中,在摇瓶中进行基础培养基、诱导条件、培养基组成成分和进程曲线的优化.结果显示,带有PelB信号肽的重组菌pET25b-CALB-1/Rosetta(DE3)在20℃...     

供氧对产丙三醇假丝酵母科丙三醇发酵研究

研究了产丙三醇假丝酵母（Ｃａｎｄｉｄａ ｇｌｙｃｅｒｏｌｇｅｎｅｓｉｓ）产丙三醇及副产物与氧供给的关系。摇瓶试验发现其它营养条件一定,玉米浆添加量决定酵母量。在０．４％的玉米浆和装液比０．０８时产丙醇最高,副产物乙醇、乙酸和乙酸乙酯最小,玉米浆和装液比影响丙三醇和副产物的形成。在５Ｌ的反应器中以搅拌转速控制供氧水平,菌体生长阶段比耗氧速率为２８ｍｇ／（ｇ．ｈ）,在发酵阶段比耗氧速率１６ｍｇ／（ｇ．     

D301树脂固定化假丝酵母脂肪酶

本研究选择7种吸附和离子交换树脂进行了假丝酵母脂肪酶(Candida sp.lipase)的固定化试验,通过测定固定化后各脂肪酶的酶活,筛选出固定化效果较好的弱碱性阴离子交换树脂D301;并通过扫描电镜将D301与脂肪酶Novozym 435的表面形貌做比较,进一步选定D301树脂作为载体,并对其采用戊二醛交联固定化,研究并优化了其固定化条件。结果表明,5%戊二醛溶液的加入量为8mL,处理时间为5h,酶液浓度为1.0g/L,磷酸缓冲盐溶液pH6.0,固定化处理10h效果最好,获得的固定化酶活力可达35U/mg,酶的固定化效率约为3.5U/(mg·h)。     

产甘油假丝酵母(Candida glycerinogenes)染色体倍性分析

摘要：【目的】产甘油假丝酵母作为一株优良高产甘油菌株,已成功应用于工业生产15年。近年来由于产甘油假丝酵母染色体倍性尚不明确,限制了对其进行遗传改造的研究进展,因而我们对产甘油假丝酵母染色体倍性研究,分析确定其染色体倍性。【方法】选用酿酒酵母细胞进行生孢,制备酿酒酵母单倍体细胞作对照,并选用热带假丝酵母作为二倍体酵母细胞对照,利用血球计数板得到热带假丝酵母、产甘油假丝酵母、单倍体及二倍体酿酒酵母细胞数,提取染色体,通过二苯胺检测法测定DNA含量。由于在相同紫外照射条件下单倍体细胞比二倍体细胞更容易死亡,因     

聚氨酯泡沫固定产脂肪酶粗状假丝酵母（Candidav alida T2）细胞的研究

对聚氨酯泡沫固定产脂肪酶粗状假丝酵母（Candida validaT2）细胞的固定化条件进行了研究。实验结果表明,聚氨酯泡沫颗粒经密度和粒径筛选,酸碱处理,以及固液比优化,载体固定细胞干质量比达到157lmg／g,细胞脂肪酶的酶活为每克干细胞1415U。电镜图片显示粗状假丝酵母菌（Candida validaT2）在载体孔隙内和脊壁上缠绕充盈,生长良好,固定结构稳定。固定化细胞连续催化水解桐籽油5批次,细胞相对水解酶活保持率达73％,固定细胞的损失率为12．5％。固定化细胞颗粒显示出良好的操作稳定性和酶活保持率,为进一步的应用研究提供了实验基础。     

Structured modeling and state estimation in a fermentation process: Lipase production by Candida rugosa

A simple structured mathematical model coupled with a methodology of state and parameter estimation is developed for lipase production by Candida rugosa in batch fermentation. The model describes the system according to the following qualitative observations and hypothesis: Lipase production is induced by extracellular oleic acid present in the medium. The acid is transported into the cell where it is consumed, transformed, and stored. Lipase is excreted to the medium where it is distributed between the available oil-water interphase and aqueous phase. Cell growth is modulated by the intracellular substrate concentration. Model parameters have been determined and the whole model validated against experiments not used in their determination. The estimation problem consists in the estimation of three state variables (biomass, intra- and extracellular substrate) and two kinetic parameters by using only the on-line measurement provided by exhaust gas analysis. The presented estimation strategy divides the complex problem into three subproblems that can be solved by stable algorithms. The estimation of biomass (X) and the specific growth rate (mu), is achieved by a recursive prediction error algorithm using the on-line measurement of the carbon dioxide evolution rate. mu is then used to perform an estimation of intracellular substrate and the other kinetic parameter related to substrate transport (A) by an adaptive observer. Extracellular substrate is then evaluated by means of the estimated values of intracellular substrate and biomass through the material balance of the reactor. Simulation and experimental tests showed good performance of the developed estimator, which appears suitable to be used for process control and monitoring. (c) 1995 John Wiley & Sons, Inc.     

Optimization of fed-batch fermentation for xylitol production by Candida tropicalis

Xylitol, a functional sweetener, was produced from xylose by biological conversion using Candida tropicalis ATCC 13803. Based on a two-substrate fermentation using glucose for cell growth and xylose for xylitol production, fed-batch fermentations were undertaken to increase the final xylitol concentration. The effects of xylose and xylitol on xylitol production rate were studied to determine the optimum concentrations for fed-batch fermentation. Xylose concentration in the medium (100 g l⁻¹) and less than 200 g l⁻¹ total xylose plus xylitol concentration were determined as optimum for maximum xylitol production rate and xylitol yield. Increasing the concentrations of xylose and xylitol decreased the rate and yield of xylitol production and the specific cell growth rate, probably because of an increase in osmotic stress that would interfere with xylose transport, xylitol flux to secretion to cell metabolism. The feeding rate of xylose solution during the fed-batch mode of operation was determined by using the mass balance equations and kinetic parameters involved in the equations in order to increase final xylitol concentration without affecting xylitol and productivity. The optimized fed-batch fermentation resulted in 187 g l⁻¹ xylitol concentration, 0.75 g xylitol g xylose⁻¹ xylitol yield and 3.9 g xylitol l⁻¹ h⁻¹ volumetric productivity. Journal of Industrial Microbiology & Biotechnology (2002) 29, 16–19 doi:10.1038/sj.jim.7000257 Received 15 October 2001/ Accepted in revised form 30 March 2002     

雷帕霉素发酵条件研究

研究了不同发酵条件对雷帕霉素产量的影响。结果显示在最优条件下,进行了100L发酵罐的发酵试验,发酵190-200h雷帕霉素的产量为1200mg／L,产量较优化前提高一倍,达到了工业化生产的要求,为进一步放大生产奠定了基础。     

脂肪酶发酵过程中的油脂利用

对假丝酵母Candidasp．99—125发酵生产脂肪酶的过程中油脂代谢情况进行了研究。分析了发酵过程中甘油酯、油酸、棕榈酸等物质浓度随发酵时间的变化趋势,以及它们与菌体生长和产酶之间相互影响关系,结果发现油酸的消耗能够显著地促进脂肪酶的合成（油酸质量浓度从30g／L降低到10g／L）,并且细胞对油酸和棕榈酸的利用没有选择性,最终发酵脂肪酶活力可达8000U／mL。     

Rhizopus sp.PW358菌脂肪酶固态发酵生产

研究了Rhizopus sp.PW358菌的固态生长和产脂肪酶条件。结果表明：黄豆饼粉为培养基的基本成分,用来生产脂肪酶。培养基中可加入淀粉和蛋白胨作为碳源和源,有利于脂肪酶的合成,培养基的含水量以及金属离子Ca^2 ,Mg^2 的浓度也影响Rhizopus sp.PW358菌和脂肪酶 产生。在优化条件下,12g豆粉中含1.0g淀粉及0.5g蛋白胨、15ml营养盐中Ca^2 ,Mg^2 离子浓度分别为8．0和4．0g/L,培养基含水量为55．6％,在接种后培养48h,酶活力可达最大值320IU／g干培养基。脂肪酶的基本性质研究表明,酶的最适反应温度和PH分别为35℃和7．0,酶的半失活温度为53．5℃,不同的PH环境中,30℃保温1h后酶在PH6．5－8．5范围内较为稳定。     

Immobilization of Candida rugosa lipase on colloidal gas aphrons (CGAs)

A novel technique for immobilization of Candida rugosa lipase onto anionic colloidal gas aphrons (CGAs) is described. CGAs are spherical microbubbles (10-100 microm) composed of an inner gas core surrounded by a surfactant shell. In this initial study, greater than 80% lipase (w/w) was effectively retained on the CGAs. Leakage of protein from the CGAs and the activity of the adsorbed lipase decreased with increasing enzyme loading; this indicates that multilayers of lipase may be adsorbing onto the CGAs. The CGA-immobilised lipase displayed normal Michaelis-Menten dependence on substrate concentration and also exhibited greater activity than the free enzyme.     

Green enzymatic production of glyceryl monoundecylenate using immobilized Candida antarctica lipase B

Enzymatic synthesis of glyceryl monoundecylenate (GMU) was performed using indigenously immobilized Candida anatarctica lipase B preparation (named as PyCal) using glycerol and undecylenic acid as substrates. The effect of molar ratio, enzyme load, reaction time, and organic solvent on the reaction conversion was determined. Both batch and continuous processes for GMU synthesis with shortened reaction time were developed. Under optimized batch reaction conditions such as 1:5 molar ratio of undecylenic acid and glycerol, 2?h of reaction time at 30% substrate concentration in tert-butyl alcohol, conversion of 82% in the absence of molecular sieve, and conversion of 93% in the presence of molecular sieve were achieved. Packed bed reactor studies resulted in high conversion of 86% in 10-min residence time. Characterization of formed GMU was performed by FTIR, MS/MS. Enzymatic process resulted in GMU as a predominant product in high yield and shorter reaction time periods with GMU content of 92% and DAG content of 8%. Optimized GMU synthesis in the present study can be used as a useful reference for industrial synthesis of fatty acid esters of glycerol by the enzymatic route.