补料方式对酵母菌生产谷胱甘肽的影响

比较了酵母菌发酵生产谷胱甘肽（GSH）的几种补料分批培养方式。实验发现补料可以明显地促进酵母菌的生长和谷胱甘肽的合成,同时还发现不同的补料方式对发酵液中的菌体浓度和GSH浓度有不同的影响。采用指数流加方式可获得极高的菌体浓度,但菌体中的GSH浓度较低;而采用恒－pH补料分批培养既可以达到较高菌体浓度,菌体中又含有较高的GSH含量,因此,其总的GSH产量最高,可达到977.8mg/L。     

谷胱甘肽的研究与应用

谷胱甘肽的研究与应用刘振玉（天津体育学院基础部,天津３００３８１）关键词还原型谷胱甘肽,氧化型谷胱甘肽谷胱甘肽（ＧＳＨ）是由谷氨酸、半胱氨酸和甘氨酸形成的三肽化合物,在生物体内有许多重要作用。合成谷胱甘肽的第一步是在谷氨酸的γ－羧基与半胱氨酸的氨基之...     

谷氨酰胺转胺酶—理化性质，生产方法及其在食品工业中的应用

谷氨酰胺转胺酶（蛋白质－谷氨酸－γ谷氨酰胺转移酶EC2,3,2,13）催化体外大多数食品蛋白质的交联反应,如：酪蛋白,大豆蛋白,肌球蛋白,肌动蛋白,谷蛋白,禽蛋蛋白等等。通过催化肽键谷酰胺基残基的酰基转移反应,在各种蛋白质分子之间或之内形成ε-（γ-谷胺酰）赖氨酸键,从而改善各种蛋白质的功能性质,如：营养价值,质地结构,口感,贮存期等等。目前,商业化谷氨酰胺转胺酶主要从动物组织中提取,但由于其分离和纯化过程较复杂,且来源稀少,因而价格昂贵,近年来,人们开始转向于研究利用微生物发酵来生产谷氨酰胺转胺酶,并使之应用于食品工业,经过微生物谷氨酸酰胺转胺酶处理后的食品,其功能性质明显改善,本文就谷氨酰胺转胺酶的国内外研究现状作一综述,主要包括理化性质,生产及其应用。     

发酵法生产谷胱甘肽的研究进展

谷胱甘肽是一种含巯基活性三肽。简要综述发酵法生产谷胱甘肽中的菌种选育、发酵调控策略、提取及分离纯化等方面的研究进展。     

构建重组乳酸乳球菌生产谷胱甘肽

以大肠杆菌染色体DNA为模板,分别扩增得到编码γ-谷氨酰半胱氨酸合成酶和谷胱甘肽合成酶的基因gsbA和gshB。将gsbA和gshB基因克隆到质粒pNZSl48中,电转化乳酸乳球菌NZ9000,获得重组菌NZ9000(pNZ3203)。在添加10mmol／L谷氨酸、半胱氨酸和甘氨酸的M17培养基中培养该重组茵,当OD600达到0、4时用乳酸链球菌素诱导4h,胞内谷胱甘肽含量达到358mmol／mg蛋白(胞内浓度相当于140mmol／L),这是在革兰氏阳性茵中生产谷胱甘肽的首例报道。     

基因工程酶法生产谷胱甘肽的工艺研究

研究了前体氨基酸和辅因子对基因工程酶法生产谷胱甘肽(GSH)的影响.实验考察了不同浓度的前体氨基酸和不同的镁离子浓度对于重组大肠杆菌酶法生产GSH产量的变化.实验结果表明,当L-Glu 60 mmol·L-1;Gly 50 mmol·L-1;L-Cys 15 mol·L-1;Mg2+ 80 mmol·L-1为酶法生产谷...     

酵母生产谷胱甘肽的培养条件研究

应用Plackett-Burman实验设计、响应面分析方法研究了酵母生产谷胱甘肽的培养条件,结果表明:最佳培养条件为初始pH 5.0,培养温度28℃,接种量10%,摇床转速200 r/min,种子液种龄22~23 h。葡萄糖1.95%,糖蜜1.95%,蛋白胨3%,Cys.HCl 0.10%,MgSO4.7H2O 0.5%,甲硫氨酸0.05%,在此优化的条件下培养,谷胱甘肽的产量达235.7 mg/L,比优化前提高45.4%。     

甜菜碱的生产方法及应用

甜菜碱是一种季铵型生物碱,其制备方法有天然提取法和人工合成法。甜菜碱及其盐酸盐是一种高效甲基供体,能调节动物体内渗透压、促进脂肪代谢和蛋白质合成、对鱼虾有良好的诱食效果,在养殖业中是重要的饲料添加剂,另外在化工、医药、食品、发酵等行业也都有广泛的应用。     

重组大肠杆菌生产谷胱甘肽发酵条件的研究

研究了重组Ｅ．Ｃｏｌｉ产ＧＳＨ的发酵条件,重点考察了添加酵母膏、前体氨基酸和ＡＴＰ的影响。结果发现,前体氨基酸和ＡＴＰ均能促进胞内ＧＳＨ的积累,若在发酵０ｈ和１２ｈ分别加入２０ｇ／ＬＡＴＰ和９ｍｍｏｌ／Ｌ前体氨基酸,则细胞干重和胞内ＧＳＨ含量可分别比对照提高２４％和１４倍。应用正交试验得出的针对细胞干重和ＧＳＨ总量的最佳组合,最大细胞干重和ＧＳＨ总量比原试验中的最好结果分别提高了１０％和２６％。在分析了该菌对葡萄糖利用情况的基础上,对该菌进行了指数流加培养,２５ｈ细胞干重与发酵液内ＧＳＨ总量分别达到８０ｇ／Ｌ和８８０ｍｇ／Ｌ,比摇瓶最好结果分别提高了８３和４６倍。     

Preparation of N-tBoc L-glutathione dimethyl and di-tert-butyl esters: versatile synthetic building blocks

The title l-glutathione derivatives, containing acid- and base-labile esters, respectively, were obtained in good overall yields. N-(t)Boc l-glutathione dimethyl ester was prepared via Fischer esterification of l-glutathione disulfide (GSSG) using HCl in dry methanol, protection of the amine with (t)Boc(2)O, and tributylphosphine cleavage of the disulfide in wet isopropanol. Alternatively, Fischer esterification and (t)Boc-protection of l-glutathione (GSH) also furnished N-(t)Boc glutathione dimethyl ester accompanied by a small amount of S-(t)Boc that was removed chromatographically. The di-tert-butyl ester was obtained by S-palmitoylation of GSH in TFA as solvent, N-(t)Boc-protection, esterification using (t)BuOH mediated by diisopropylcarbodiimide/copper(I) chloride, and saponification of the thioester. These l-glutathione derivatives are versatile synthetic building blocks for the preparation of S-glutathione adducts.     

Applications of sexed semen in cattle production

Sexed semen will contribute to increased profitability of dairy and beef cattle production in a variety of ways. It could be used to produce offspring of the desired sex from a particular mating to take advantage of differences in value of males and females for specific marketing purposes. Commercial dairy farmers, those who produce and market milk, could use sexed semen to produce replacement daughters from genetically superior cows and beef crossbred sons from the remainder of their cow population. To increase the rate of response to selection, seedstock dairy cattle breeders could produce bulls for progeny testing from a smaller number of elite dams by using sexed semen to ensure that all of them produced a son. Using sexed semen could then reduce the cost of progeny testing those bulls, because fewer matings would be necessary to produce any required number of daughters. Commercial beef cattle farmers, producing animals for eventual slaughter, could use sexed semen to capitalize on the higher value of male than female offspring for meat production. They could also use sexed semen to produce specialized, genetically superior replacement heifers from as small a proportion of the herd as possible. This would allow the remainder of the herd to produce male calves from bulls or breeds with superior genetic merit for growth, feed conversion efficiency, and carcass merit. Single-sex, bred-heifer systems, in which each female is sold for slaughter soon after weaning her replacement daughter, would be possible with the use of X-chromosome-sorted semen. Use of sexed semen would make terminal crossbreeding systems more efficient and sustainable in beef cattle. Fewer females would be required to produce specialized maternal crossbred daughters, and more could be devoted to producing highly efficient, terminal crossbred sons.     

Applications of microbial co-cultures in polyketides production

Polyketides are a large group of natural biomolecules that are normally produced by bacteria, fungi and plants. These molecules have clinical importance due to their anti-cancer, anti-microbial, anti-oxidant and anti-inflammatory properties. Polyketides are biosynthesized from units of acyl-CoA by different polyketide synthases (PKSs), which display wide diversity of functional domains and mechanisms of action between fungi and bacteria. Co-culture of different micro-organisms can produce novel products distinctive from those produced during single cultures. This study compared the new polyketides produced in such co-culture systems and discusses aspects of the cultivation systems, product structures and identification techniques. Current results indicate that the formation of new polyketides may be the result of activation of previously silent PKSs genes induced during co-culture. This review indicated a potential way to produce pure therapeutic polyketides by microbial fermentation and a potential way to develop functional foods and agricultural products using co-co-culture of different micro-organisms. It also pointed out a new perspective for studies on the process of functional foods, especially those involving multiple micro-organisms.     

Applications of systems biology towards microbial fuel production

Harnessing the immense natural diversity of biological functions for economical production of fuel has enormous potential benefits. Inevitably, however, the native capabilities for any given organism must be modified to increase the productivity or efficiency of a biofuel bioprocess. From a broad perspective, the challenge is to sufficiently understand the details of cellular functionality to be able to prospectively predict and modify the cellular function of a microorganism. Recent advances in experimental and computational systems biology approaches can be used to better understand cellular level function and guide future experiments. With pressure to quickly develop viable, renewable biofuel processes a balance must be maintained between obtaining depth of biological knowledge and applying that knowledge.     

Applications of microbial fermentations for production of gluten-free products and perspectives

A gluten-free (GF) diet is recognised as being the only accepted treatment for celiac disease—a permanent autoimmune enteropathy triggered by the ingestion of gluten-containing cereals. The bakery products available in today’s gluten-free market are characterised by lower palatability than their conventional counterparts and may lead to nutritional deficiencies of vitamins, minerals and fibre. Thus, the production of high-quality gluten-free products has become a very important socioeconomical issue. Microbial fermentation by means of lactic acid bacteria and yeast is one of the most ecological/economical methods of producing and preserving food. In this review, the role of a fermentation process for improving the quality of GF products and for developing a new concept of GF products with nutraceutical and health-promoting characteristics will be examined.     

Applications of modelling for bioprocess design and control in industrial production

The on-line measurement of the relevant parameters and the control conception for three production processes for fine chemicals by fermentation and biotransformation at the 15 m³ scale were developed. The models describe the bioprocesses which successfully result in fully automated manufacturing steps. Modelling also proved to be a valuable tool for a better insight into biochemical fundamentals of the processes. Moreover, proper use of data logging, modelling and process control was important for quality, since two processes were controlled on-line and quality relevant deviations were registered early. Finally, combining modelling with simulation, we could drastically reduce both development time and cost.List of Symbols F l/h flux - V l volume - U ₀ g/l nicotinonitrile concentration influx - U g/l actual nicotinonitrile concentration - q _ug/gh specific educt (=nicotinonitrile) transformation rate - x g/l biocatalyst concentration - p ₀ g/l nicotinamide concentration influx - p g/l actual nicotinamide concentration - q _pg/gh specific product (=nicotinamide) formation rate - k parameter loss of activity - q _{u, max}g/gh max. specific educt transformation rate - K _ug/l saturation constant for nicotinonitrile - K _ig/l inhibition constant for nicotinonitrile - K _iig/l inhibition constant for nicotinamide - MW _Ag/mol molecular weight for nicotinonitrile - MW _Bg/mol molecular weight for nicotinamide - NS Nicotinic acid - 6-HNS 6-Hydroxynicotinic acid - r _{NS, 6HNS} g/lh 6-HNS production rate - r _{6HNS, X} g/lh biomass production rate - r _{NS, 6HNS, max} g/lh max. 6-HNS production rate - S _NS g/l actual NS concentration - K _{S, NS} g/l saturation constant for NS - K _{i, 6HNS} g/l inhibition constant for 6-HNS - K _o2 g/l saturation constant for oxygen - r _{6HNS, X, max} g/lh max. biomass production rate - S _6HNS g/l actual 6-HNS concentration - K _{ii, NS} g/l inhibition constant for NS - RQ mol/mol respiration quotient - S _xylg/l actual xylene concentration - K _{i, xyl}g/ inhibition constant for xylene - K _{i, DMPY}g/ inhibition constant for 2,5-dimethylpyrazine - r _Xg/lh biomass production rate - r _{X, max}g/lh max. biomass production rate - K _{s, xyl}g/l saturation constant for xylene - S _DMPYg/l actual concentration of DMPY - K _{i, MPCA}g/ inhibition constant for MPCA - K _O2g/ saturation constant for oxygen - S _MPCAg/l actual MPCA concentration - S _O2g/l actual oxygen concentration - r _MPCAg/lh MPCA production rate - r _{MPCA, max}g/lh max. MPCA production rate - k _lgl inhibition constant for the intermediates - k _{s, DMPY}gl saturation constant for DMPY     

Microcarrier culture: Applications in biological production and cell biology

This report reviews recent progress in micro carrier technology at the Massachusetts Institute of Technology. This progress includes new understanding of the nutritional needs of high-cell density micro carrier cultures, the demonstration of cell growth on microcarriers in a hormone-supplemented, serum-free medium, and the continuous cell propagation of epithelial cell types in microcarrier culture by medium modification that permits efficient bead-to bead transfer. Also, a technique for obtaining large quantities of mitotic cells by selective detachment from microcarriers is reported. Finally, recent progress in interferon production from human foreskin fibroblasts grown on microcarriers is outlined: Our improvements in the interferon “super induction” process have increased the interferon yield per cell fivefold to tenfold.     

Biopharmaceutical production: Applications of surface plasmon resonance biosensors

Surface plasmon resonance (SPR) permits the quantitative analysis of therapeutic antibody concentrations and impurities including bacteria, Protein A, Protein G and small molecule ligands leached from chromatography media. The use of surface plasmon resonance has gained popularity within the biopharmaceutical industry due to the automated, label free, real time interaction that may be exploited when using this method. The application areas to assess protein interactions and develop analytical methods for biopharmaceutical downstream process development, quality control, and in-process monitoring are reviewed.     

微生物耐受乙醇与丁醇机制及其在生物燃料生产与生物转化中的应用

生物法获取乙醇与丁醇过程中有机溶剂的毒性是生产菌重要环境胁迫因素之一,且当有机溶剂超过一定浓度时便会抑制微生物的生长,甚至引起微生物的死亡,因此提高工业微生物的有机溶剂耐受性对工业生产具有重要的意义。对微生物乙醇及丁醇耐受机制的研究可为选育具有较强溶剂耐受菌提供理论基础。本文系统介绍了微生物耐受乙醇与丁醇的机制,并对其在生物燃料生产及生物转化中面临的机遇与挑战等问题进行简要的评述。