褐藻胶寡糖制备的研究进展

褐藻胶寡糖(alginate oligosaccharides,AOS)是褐藻胶降解而形成的一种功能性寡糖,具有广泛的生物活性,如促进植物生长、提高植物抗逆性、抗氧化、抗菌、抗肿瘤等。褐藻胶寡糖的制备方法主要分为:化学法、物理法和酶解法。不同的方法制备出的褐藻胶寡糖结构亦有所不同。介绍了化学法、物理法和酶解法等各种褐藻胶寡糖制备方法的研究现状、存在的问题及发展趋势。     

褐藻胶寡糖生物活性研究进展

褐藻寡糖AOS由β-D-甘露糖醛酸(ManA)和α-L-古洛糖醛酸(GulA)通过1-4糖苷键连接而成,具有广泛的生物活性,如促进植物生长、缓解植物非生物胁迫、抗肿瘤、抑菌等作用,在绿色农业、医药保健等领域具有广阔的前景。本文综述了近几年来褐藻胶寡糖在生物活性方面的研究进展,并对其应用前景进行了展望。     

微生物来源褐藻胶(alginate)生物合成及应用前景

褐藻胶及其制品在医药、食品及化工等领域具有重要价值。除褐藻以外,微生物是褐藻胶的另一重要来源。虽然微生物来源的褐藻胶未能够实现规模化生产,但是由于微生物合成褐藻胶具有发酵条件可控、产物单一、结构稳定并且易于纯化等优势,引起广泛的关注。并且利用生物工程技术已经实现了对微生物来源褐藻胶结构的调控和改造,促进了褐藻胶的高值化利用。此文综述了微生物褐藻胶生物合成的概况,并对利用基因工程改造褐藻胶的发展趋势和应用前景进行了论述。     

褐藻寡糖生物法制备研究进展 *

褐藻寡糖(alginate oligosaccharides,AOS)是褐藻胶的降解产物,具有抗氧化、调节免疫、调节血脂、促进细胞生长等生理活性,应用范围广泛。现有的AOS 制备法主要分为物理法、化学法和生物法。介绍AOS的生物法制备包括酶解、微生物全细胞发酵和生物合成法,基因工程的应用在改造产褐藻胶裂解酶的菌株以提高生物法效率方面具有重要意义。此外,规模化的AOS生物法制备案例进行了科学引证,并展望了未来 AOS规模化制备的发展方向,以期为 AOS 的工业化制备和应用提供参考。     

微生物发酵-膜分离法制备褐藻胶寡糖及其产物分析

比较褐藻胶裂解酶产生菌Alteromonassp .在摇瓶和发酵罐培养过程中生物量、褐藻胶寡糖含量以及褐藻胶裂解酶活性的变化 ,根据其变化确立了通过微生物发酵 膜分离技术结合制备褐藻胶寡糖的条件 ,并对寡糖进行凝胶过滤色谱和薄层色谱分析。用组成为每升含酵母粉 5g、蛋白胨 10g、FeSO4 0 1g、褐藻酸钠 12g、NaCl 1 5g ,pH为7 5的培养基 ,在 2 8℃培养褐藻胶裂解酶产生菌 ,结果表明 ,发酵罐培养 30h ,发酵液寡糖含量达到最大。发酵液通过超滤 纳滤两级膜分离 ,得到褐藻胶寡糖 ,寡糖的回收率和脱盐率分别为 94 0 %和 93 3%。通过凝胶柱分离和TLC分析 ,得到 5个褐藻胶寡糖组分。     

一株产褐藻胶裂解酶的需钠弧菌筛选及酶解产物分析

[背景]褐藻胶裂解酶种类丰富、降解机制多样,是高效环保降解褐藻胶、制备褐藻寡糖的工具酶,成为褐藻植物高值化开发利用的研究热点.[目的]从海泥中筛选获得褐藻胶裂解酶高效产酶菌株,确定菌株发酵产酶最优条件,鉴定和分析酶降解产物,进而解析该酶的降解特性.[方法]以褐藻胶为唯一碳源,从海带养殖场附近海泥中筛选菌株,通过形态学观...     

褐藻胶降解菌的筛选、鉴定及产酶条件优化

【目的】筛选一株能降解褐藻胶的菌株,并优化产酶条件以提高褐藻胶裂解酶活力。【方法】从漳州海域采集到海水和海泥,以海藻酸钠为唯一碳源,通过富集培养、初筛、复筛筛选到一株能够降解褐藻胶的菌株。依据16S rRNA序列分析、生理生化特征、菌体形态及菌落特征对该菌进行鉴定。通过单因素和正交试验对该菌的产酶条件进行优化。【结果】该菌属于海科贝特氏菌,命名为Cobetiamarina HQZ08。该菌株最佳的产酶培养基组成为:海藻酸钠7.00g/L、蛋白胨3.00g/L、NaCl30.00g/L,K2HPO4·3H2O 1.25 g/L。最佳发酵条件为:接种量2%,接种龄12 h,培养基起始pH为7.0,培养温度25°C,培养时间24 h。优化后褐藻胶裂解酶活力达到68.5 U/mL,TLC法分析酶解产物为褐藻胶寡糖。【结论】HQZ08菌株可以用于降解褐藻胶,产生聚合度为2–6的褐藻胶寡糖。     

海藻工具酶——褐藻胶裂解酶研究进展

从海洋生物中筛选提取有价值的酶类,开发海洋多糖降解产物,已成为海洋生物资源开发的一个重要方面。因此,近年来对于海藻工具酶之一的褐藻胶裂解酶及其降解产物——褐藻寡糖的研究日益受到人们的普遍关注。从褐藻胶裂解酶的来源、分类、底物专一性、作用方式及结构与机理研究、酶活力测定和酶学性质等方面,结合本课题组的研究工作综述近十年来有关褐藻胶裂解酶的研究进展。     

产褐藻胶裂解酶芽胞杆菌的筛选、鉴定及其降解效果评价

褐藻胶是广泛存在于褐藻中的一类多糖,降解为褐藻寡糖后能表现出更多的生物活性。从海洋样品中筛选出产褐藻胶裂解酶芽胞细菌16株,基于形态、生理生化特征和16S r DNA系统发育分析初步鉴定菌株HB12274为解淀粉芽胞杆菌植物亚种(Bacillus amyloliquefaciens subsp. plantarum)。TLC结果显示,海藻酸钠经粗酶液降解形成2～7聚合度的褐藻寡糖和单糖,菌株与马尾藻叶片共培养时能明显降解叶状体结构。为褐藻胶裂解酶的生产和工业应用提供了新的菌株来源。     

海带多糖生物活性的研究进展

海带中富含功能性物质,其中海带多糖主要包括褐藻胶、褐藻糖胶、褐藻淀粉三种,其分离提取工艺还不是太成熟,海带多糖结构迥异、性质不同,具有复杂的多方面的生物活性,在调节免疫、抗肿瘤、抗凝血、降血脂、降血糖、抗辐射、抗突变、抗体内氧化和耐缺氧等方面具有独特的功能。     

Alginate lyase: Structure,property, and application

Alginate is a linear polysaccharide in which β-D-mannuronate (M) and its epimer, α-L-guluronate (G), are covalently (1–4)-linked in different sequences. Alginate is mainly used as a food additive to modify food texture due to its high viscosity and gelling property. Alginate lyase can degrade alginate by cleaving the glycosidic bond through a β-elimination reaction, generating oligomer with 4-deoxy-L-erythro-hex-4-enepyranosyluronate at the nonreducing end. Alginate oligosaccharides have been shown to stimulate the growth of human endothelial cells and the secretion of cytotoxic cytokines from human macrophage. Alginate can be converted into unsaturated monosaccharide by saccharification process using endolytic and exolytic alginate lyases, thus alginate lyases have potential as key biocatalyst for application of alginate as a renewable source for biochemicals and biofuels in near future. In this paper, structures and functions of various alginate lyases are reviewed. Prospects on future applications of alginate lyases are also discussed.     

海藻酸钠微胶囊制备及其在微生物包埋中的应用

海藻酸钠微胶囊作为一种包埋系统,因其价廉、无毒、生物相容性好、可生物降解等优点而备受关注。海藻酸钠微胶囊制备的研究一直是微胶囊制备的重要组成部分。本文概述了近年来海藻酸钠微胶囊的研究进展,包括主要制备方法及其影响因素,包埋微生物以改善微生物的应用性能等方面,并展望了海藻酸钠微胶囊在工业微生物等领域的发展。     

Bacterial alginates: from biosynthesis to applications

Alginate is a polysaccharide belonging to the family of linear (unbranched), non-repeating copolymers, consisting of variable amounts of β-d-mannuronic acid and its C5-epimer α- l-guluronic acid linked via β-1,4-glycosidic bonds. Like DNA, alginate is a negatively charged polymer, imparting material properties ranging from viscous solutions to gel-like structures in the presence of divalent cations. Bacterial alginates are synthesized by only two bacterial genera, Pseudomonas and Azotobacter, and have been extensively studied over the last 40 years. While primarily synthesized in form of polymannuronic acid, alginate undergoes chemical modifications comprising acetylation and epimerization, which occurs during periplasmic transfer and before final export through the outer membrane. Alginate with its unique material properties and characteristics has been increasingly considered as biomaterial for medical applications. The genetic modification of alginate producing microorganisms could enable biotechnological production of new alginates with unique, tailor-made properties, suitable for medical and industrial applications.     

海藻酸钠寡糖对小鼠免疫及 抗氧化功能的影响

目的研究海藻酸钠寡糖对小鼠免疫及抗氧化活性的影响。方法采用不同浓度的海藻酸钠寡糖分别对小鼠连续灌胃15d后,测量小鼠生长性能、小鼠胸腺和脾脏指数以及小鼠血浆中SOD和GSH的活性。结果海藻酸钠寡糖能促进小鼠的生长性能,提高小鼠的胸腺和脾脏指数。其中给小鼠灌注高浓度的海藻酸钠寡糖15d后,与对照组相比,小鼠的特定生长率和增重率分别提高了37.0%和48.5%(P0.01),小鼠胸腺和脾脏指数分别提高了18.8%和21.7%(P0.01)。海藻酸钠寡糖还能增加小鼠的抗氧化活性,与对照组相比,灌注高浓度海藻酸钠寡糖组小鼠的SOD和GSH-Px活性分别提高了92.6%和35.9%(P0.01)。结论海藻酸钠寡糖能促进小鼠的生长性能,增强小鼠的免疫和抗氧化功能。     

来自Yeosuana marina sp.JLT21内切型海藻酸裂解酶的异源表达及酶学表征

褐藻寡糖有着丰富的生物学功能,酶法制备功能性褐藻寡糖具有重要实践应用价值.为发掘高活性及稳定性的褐藻寡糖制备酶,对浅海热液嗜热菌Yeosuana marina sp.JLT21中的海藻酸裂解酶YMA-1的基因在大肠杆菌中进行表达、纯化及酶活鉴定.结果发现YMA-1由306个氨基酸残基构成,是多糖裂解酶家族7(PL7)新...     

Pellet culture elicits superior chondrogenic redifferentiation than alginate‐based systems

Although pellet culture and encapsulation of chondrocytes into gel‐like biomaterials have lead to major advances in cartilage tissue engineering, a quantitative comparative characterization of cellular differentiation behavior during those cultivation procedures has not yet been performed. Our study therefore aimed at answering the following question: is the redifferentiation pathway of chondrocytes altered by slight changes in the type of alginate biomaterial (pure alginate, alginate‐fibrin, alginate‐chitosan) and how do the cells behave in comparison to biomaterial‐free (pellet) three‐dimensional culturing? Monolayer‐expanded chondrocytes from healthy adult porcine knee joints were cultivated in alginate, alginate‐chitosan, alginate‐fibrin beads and as pellets up to 4 weeks. Quantitative PCR and Immunohistology were used to assess chondrogenic markers. Alginate‐fibrin—encapsulated chondrocytes behaved almost like monolayer chondrocytes. Alginate‐ and alginate‐chitosan encapsulation lead to a low chondrogenic marker gene expression. Although all 3D‐cultured chondrocytes showed a considerable amount of Sox9 expression, only pellet cultivation lead to a sufficient Collagen II expression. This puts the usage of alginate‐cultivated cartilage tissue engineering constructs under question. Fibrin addition is not beneficial for chondrogenic differentiation. Sox9 and Collagen II behave differently, depending upon the surrounding 3D‐environment. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Bridging the bio-electronic interface with biofabrication

Advancements in lab-on-a-chip technology promise to revolutionize both research and medicine through lower costs, better sensitivity, portability, and higher throughput. The incorporation of biological components onto biological microelectromechanical systems (bioMEMS) has shown great potential for achieving these goals. Microfabricated electronic chips allow for micrometer-scale features as well as an electrical connection for sensing and actuation. Functional biological components give the system the capacity for specific detection of analytes, enzymatic functions, and whole-cell capabilities. Standard microfabrication processes and bio-analytical techniques have been successfully utilized for decades in the computer and biological industries, respectively. Their combination and interfacing in a lab-on-a-chip environment, however, brings forth new challenges. There is a call for techniques that can build an interface between the electrode and biological component that is mild and is easy to fabricate and pattern. Biofabrication, described here, is one such approach that has shown great promise for its easy-to-assemble incorporation of biological components with versatility in the on-chip functions that are enabled. Biofabrication uses biological materials and biological mechanisms (self-assembly, enzymatic assembly) for bottom-up hierarchical assembly. While our labs have demonstrated these concepts in many formats, here we demonstrate the assembly process based on electrodeposition followed by multiple applications of signal-based interactions. The assembly process consists of the electrodeposition of biocompatible stimuli-responsive polymer films on electrodes and their subsequent functionalization with biological components such as DNA, enzymes, or live cells. Electrodeposition takes advantage of the pH gradient created at the surface of a biased electrode from the electrolysis of water. Chitosan and alginate are stimuli-responsive biological polymers that can be triggered to self-assemble into hydrogel films in response to imposed electrical signals. The thickness of these hydrogels is determined by the extent to which the pH gradient extends from the electrode. This can be modified using varying current densities and deposition times. This protocol will describe how chitosan films are deposited and functionalized by covalently attaching biological components to the abundant primary amine groups present on the film through either enzymatic or electrochemical methods. Alginate films and their entrapment of live cells will also be addressed. Finally, the utility of biofabrication is demonstrated through examples of signal-based interaction, including chemical-to-electrical, cell-to-cell, and also enzyme-to-cell signal transmission. Both the electrodeposition and functionalization can be performed under near-physiological conditions without the need for reagents and thus spare labile biological components from harsh conditions. Additionally, both chitosan and alginate have long been used for biologically-relevant purposes. Overall, biofabrication, a rapid technique that can be simply performed on a benchtop, can be used for creating micron scale patterns of functional biological components on electrodes and can be used for a variety of lab-on-a-chip applications.     

Development of a microchannel emulsification process for pancreatic beta cell encapsulation

In this study, we developed a high-throughput microchannel emulsification process to encapsulate pancreatic beta cells in monodisperse alginate beads. The process builds on a stirred emulsification and internal gelation method previously adapted to pancreatic cell encapsulation. Alginate bead production was achieved by flowing a 0.5–2.5% alginate solution with cells and CaCO₃ across a 1-mm thick polytetrafluoroethylene plate with 700 × 200 μm rectangular straight-through channels. Alginate beads ranging from 1.5–3 mm in diameter were obtained at production rates exceeding 140 mL/hr per microchannel. Compared to the stirred emulsification process, the microchannel emulsification beads had a narrower size distribution and demonstrated enhanced compressive burst strength. Both microchannel and stirred emulsification beads exhibited homogeneous profiles of 0.7% alginate concentration using an initial alginate solution concentration of 1.5%. Encapsulated beta cell viability of 89 ± 2% based on live/dead staining was achieved by minimizing the bead residence time in the acidified organic phase fluid. Microchannel emulsification is a promising method for clinical-scale pancreatic beta cell encapsulation as well as other applications in the pharmaceutical, food, and cosmetic industries.