Intraparticle cell growth and cell leakage in cultures of Nicotiana tabacum cells immobilized in calcium alginate gel beads

Immobilized Nicotiona tabacum cells in calcium alginate gel beads were prepared under various conditions and then were cultivated. The effects of different conditions of preparation, in relation to concentration of calcium ions (Ca²⁺), on intraparticle cell growth and cell leakage from beads were investigated experimentally. As the amount of Ca²⁺ incorporated into the beads increased, the numbers of cells leaked from the beads into the medium decreased. However, cell growth was inhibited by high Ca²⁺ concentrations in the beads. Optimal conditions existed, which prevented cell leakage without inhibiting intraparticle cell growth. The effect of adding CaCl₂ to the culture medium was also studied. The Ca²⁺, used for the alginate crosslinking, gradually leached from the beads with increasing cultivation time, such that the beads gradually became brittle and fragile. The addition of CaCl₂ was effective in preventing Ca²⁺ loss from the beads and cell leakage. © 2000 Society of Chemical Industry     

海藻酸钠包埋高效菌种强化处理聚酯废水的试验研究

对海藻酸钠-氯化钙法包埋某高效微生物菌种用于强化聚酯废水的生物处理进行了试验研究,同时将其与普通系统和高效菌种的悬浮投加型强化系统作了相应比较.结果表明:相对普通系统,悬浮投加高效菌种可使出水COD降低100mg/L,处理率提高8%,而用海藻酸钠-氯化钙法包埋固定化之后投加则可使出水COD降低200mg/L,处理率提高14%,使最终出水COD达到100mg/L以下,达到出水的排放要求,且减少了废水中对人类和环境有较大危害的1,4-二氧杂环己烷的含量.     

Production of lactic acid from beet molasses by calcium alginate immobilized Lactobacillus delbrueckii IFO 3202

Lactic acid was produced from pretreated beet molasses by the homofermentative organism Lactobacillus delbrueckii subsp delbrueckii IFO 3202 entrapped in calcium alginate gel using batch, repeated batch and continuous fermentation systems. In batch fermentation studies successful results were obtained with 2.0–2.4 mm diameter beads prepared from 2% sodium alginate solution. The highest effective yield (82.0%) and conversion yield (90.0%) were obtained from substrate concentrations of 52.1 and 78.2 g dm⁻³ respectively. The gel beads produced lactic acid for 14 consecutive batch fermentations without marked activity loss and deformation. In the continuous fermentation, the highest lactic acid (4.22%) was obtained at a dilution rate of 0.1 h⁻¹ while the highest productivity (13.92 g dm⁻³ h⁻¹) was obtained at a dilution rate of 0.4 h⁻¹. © 1999 Society of Chemical Industry     

海藻酸铝固定化糖化酶特性研究

采用海藻酸铝固定化糖化酶,对固定化酶和游离酶的特性进行了比较。结果表明,固定化酶米氏常数Km为13.72 mg/mL,最适温度为65℃,半衰期为100.7 d,固定化糖化酶的活力回收率达61.8%。     

Evaluation of lipase from Burkholderia cepacia immobilized in alginate beads and application in the synthesis of banana flavor (isoamyl acetate)

The alginate in bead forms was used to immobilize Burkholderia cepacia lipase. The microencapsulation technique for lipase entrapment was a 2% (w/v) of sodium alginate concentration prepared by ionic gelation using calcium chloride as the cross-linking agent in a gelling solution. The beads were tested in different solvents as acetone, chloroform, toluene, n-hexane, and n-heptane. Over a 5-day period (120?h), the n-heptane maintained the reasonable (excellent) residual activity of the immobilized lipase. Morphological studies on reused beads and new beads were performed. All beads for isoamyl acetate yield were tested. The reused bead leaches substantially, with a maximum ester yield of 92%. With modifications in the molar ratios, the synthesis of banana flavor (isoamyl acetate) was performed in both the alcohol per acid and acid per alcohol excesses.     

Modification of S1 subsite specificity in the cysteine protease cathepsin B

Cysteine proteases of the papain family generally exhibit broadP₁ specificity. A notable exception is papaya proteinase IV(PPIV), which only accepts Gly at this position. In all othercysteine proteases the S₁ subsite residues 23 and 65 (papainnumbering) are absolutely conserved as Gly, while in PPIV theyare replaced by Glu and Arg, respectively. These differencesappear to underlie both PPIV specificity and its resistanceto inhibition by cystatins. To test this hypothesis, the equivalentresidues (Gly27 and Gly73) in the mammalian cysteine proteasecathepsin B were changed to Glu and Arg, respectively. Relativeto the wild-type enzyme, the Gly27Glu and Gly73Arg mutants showeda drastic reduction in activity with substrates containing aP₁ Arg. In contrast, substrates having a Gly residue in P₁ werehydrolyzed effectively. The double mutant (Gly27Glu:Gly73Arg)exhibited no detectable activity against any substrate studied.Inhibition of the Gly73Arg mutant by E-64 [1-(L-trans-epoxysuccinyl-L-leucylamino)-4-guanidinobutane]was found to be similar to that of the wild-type enzyme. Incontrast, inhibition by cystatin C exhibited a 20 000-fold reduction.These results demonstrate the dramatic influence of side chainsat sequence locations 27 and 73 on the S₁ subsite specificityof cysteine proteases.     

丙烯腈接枝改性海藻酸钙水凝胶中水杨酸的释放行为

将海藻酸钙水凝胶与丙烯腈单体进行不同程度的接枝共聚改性,再由FTIR加以分析,并测定包埋了水杨酸模拟药物的改性海藻酸钙水凝胶在不同介质中的药物释放量。实验表明,改性海藻酸钙水凝胶的药物释放量既与介质有关,也取决于接枝率的大小。     

高压静电法制备单分散性的海藻酸钙微胶珠

In this paper, the effect of operation parameters on the monodispersity of calcium-alginate gel beads prepared in high-voltage electrostatic field were analyzed. The parameters included the applied potential （U）, the distribution of electrostatic field, the frequency and the flow rate of solution through the capillary. Furthermore, the process is analyzed with the theory of jet break-up in electrostatic field. The result showed that the modified symmetrical electrostatic field was more advantageous in preparing the monodispersed gel beads than the traditional method. Meanwhile, gel beads with good monodispersity （CV〈20%） and stability without aggregation were produced under a range of applied potential （U）, frequency and flow rate of solution through the capillary.     

Studies of L-phenylalanine production by immobilised aminoacylase in stabilized calcium alginate beads

Aminoacylase I (EC 3.5. 1.14) was immobilised by entrapment in uncoated calcium alginate beads and calcium alginate beads coated with chitosan, polyethyleneimine and polyethyleneimine-glutaraldehyde for the production of L-phenylalanine by the hydrolysis of a racemic mixture of N-acetyl-DL-phenylalanine. The operational stability, thermal stability, effects of pH and temperature and kinetic constants, K_m and V_max values of free and immobilised enzymes were studied. Scanning electron micrographs revealed differences in the structures of the surfaces of coated and uncoated beads. Chitosan-coated calcium alginate beads was found to be the best among the immobilised systems studied. The activity and the optimum temperature of immobilised aminoacylase were higher than those of the free enzyme. In addition, the beads showed stable activity under operational conditions. The immobilised aminoacylase lost about 20% of its initial activity after ten cycles of reuse. Polyethyleneimine and polyethyleneimine-glutaraldehyde treatments were also found to enhance the operational stability of the enzyme but its activity was greatly reduced.     

多通道微胶囊制备系统规模化制备海藻酸钙微胶珠

利用自制多通道强制电场微胶囊制备系统制备海藻酸钙微胶珠,分析了微胶囊制备系统中电极电场分布规律,考察了进料气压、脉冲电压、脉冲频率、脉冲宽度、辅助电压等系统调节参数对微胶珠制备过程的影响,发现制备过程中微胶珠粒径大小与产率主要由进料气压决定,而微胶珠的分散性则是由多个因素共同作用的结果。通过优化条件制备的微胶珠分散系数较小（CV<20%）,球形度良好,表面光洁,并且产率是传统静电法的20~40倍,使海藻酸钙微胶珠大规模制备成为可能。     

Characterization of the structure and diffusion behavior of calcium alginate gel beads

A simple and novel method using gel shrinkage to indirectly characterize the structure of calcium alginate gel (CAG) beads during the calcium alginate gelation process was presented in this study. The effect of preparation process parameters (gelling cations, bead diameter, and alginate M _w and concentration) on the structure of the CAG bead formation process was thoroughly investigated. It was found that (a) the concentration of the Na⁺ and Ca²⁺ ion in gel bath was found to be the determining factor in the gel structure formation process by regulating the dissociation of alginate and the complexation of the calcium; (b) Na⁺ acts as a competitor with calcium and a screen in the electrostatic repulsion; (c) the effect of beads size below 700 μm on the structure of CAG beads can be neglected; and (d) the sodium alginate concentration has no significant effect on the gel formation process. Furthermore, the diffusion of bovine serum albumin (BSA) was controlled by the density of CAG bead. Consequently, a faster diffusion rate of BSA within the looser structure of beads can be observed. These results are keys to understanding the behavior and performance of beads in their utilization medium. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48923.     

Immobilization of hybridoma cells in chitosan alginate beads

A new method for immobilizing hybridoma cells using chitosan-stabilized calcium alginate beads was developed. The ionotropic gelation of chitosan and calcium with alginate resulted in the formation of highly cross-linked, porous beads that were mechanically and chemically stable in phosphate buffered medium. Hybridomas entrapped in these beads were cultured semi-continuously using periodic medium exchange. Viable population densities in the order of 5 × I0⁷ cells/mL were attained within the beads and up to two-fold increases in volumetric monoclonal antibody (MAb) productivity over batch suspension cultures were observed. Oxygen mass transfer limitations within the chitosan-alginate beads were evaluated by considering biokinetics and diffusive transport. Model equations were developed and used to evaluate the effect of bead diameter on the contained cells. The predictions were consistent with experimental observations of maximum viable population densities attained in beads of various size.     

乙酸乙烯酯接枝改性海藻酸钙凝胶微球

为了降低海藻酸钙凝胶微球的溶胀度,以乙酸乙烯酯（VAc)对海藻酸钠进行自由基接枝共聚,进而制备具有较低溶胀度的聚乙酸乙烯酯改性海藻酸钙(Ca-SA-PVAc)凝胶微球。红外光谱表明,改性之后海藻酸钙的分子上生成新的化学键;热重分析表明,改性微球受热失水行为发生变化,热稳定性提高;扫描电镜表明,改性微球结构孔隙结构发达;接枝反应条件如反应温度、VAc的浓度、引发剂用量、海藻酸钠浓度、钙离子浓度及反应时间等对改性凝胶微球在生理盐水中的抗溶胀性具有不同程度的影响。通过改变反应条件以控制接枝反应参数,可以获得溶胀行为可控的改性海藻酸钙凝胶微球。     

Production of bioethanol by immobilized Saccharomyces Cerevisiae onto modified sodium alginate gel

BACKGROUND: Microbial bioethanol production is an important option in view of the finite global oil reserves. Bioethanol fermentation was carried out using immobilized microorganisms (Saccharomyces cerevisiae, Zymomonas mobilis, Pichia stipitis, etc.), which has many advantages compared with the use of free cells. Various support materials have been used for bioethanol fermentation, and alginate gels have been one of the most widely used matrices for cell entrapment. The aim of this study was increased bioethanol production by Saccharomyces cerevisiae immobilized on alginate gels. First, N‐vinyl‐2‐pyrrolidone was grafted onto sodium alginate. Then, the properties of ethanol production were investigated using the matrix obtained. RESULTS: The performance of ethanol fermentation was affected by calcium chloride concentration, N‐vinyl‐2‐pyrrolidone grafted onto the sodium alginate, sugar concentration and the percentage of immobilized cell beads. These effects were optimized to give maximum ethanol production. Ethanol production was accelerated when sodium alginate polymer was modified with N‐vinyl‐2‐pyrrolidone. The maximum concentration, productivity and yield of ethanol were 69.68 g L^?1, 8.71 g L^?1 h^?1 and 0.697 g g^?1, respectively. CONCLUSION: The new polymeric matrix, when compared with sodium alginate, showed better ethanol production due to the hydrophilic property of N‐vinyl‐2‐pyrrolidone. The results suggest that the proposed method for immobilization of Saccharomyces cerevisiae has potential in industrial applications of the ethanol production process. Copyright © 2011 Society of Chemical Industry     

海藻酸钙固定化零价铁抗团聚及堵塞的作用机制

以海藻酸钠(SA)、氯化钙、微米零价铁(MZVI)为原料,制备了海藻酸钙(CA)固定化MZVI填料(CAZ),通过静态烧杯实验和动态PRB模型实验,探讨了CA运用对Cr(Ⅵ)的去除性能的影响,并通过电镜扫描分析了CA避免团聚、堵塞机制。实验结果表明,CA凝胶颗粒的运用能显著提升MZVI的除Cr(Ⅵ)性能,CAZ相比MZVI对Cr(Ⅵ)的去除率和反应速率分别提升7.1倍、23.0倍;MZVI利用率的提高是CAZ反应器处理Cr(Ⅵ)水量显著大于MZVI反应器的主要原因,MZVI反应速率的提高是CAZ反应器出水Cr(Ⅵ)浓度显著低于MZVI反应器的主要原因。电镜扫描结果表明,SA与氯化钙交联形成的CA具有丰富的骨架孔道结构,具有骨架支撑作用,能有效克服MZVI颗粒因重力作用导致团聚、降低比表面积的缺陷。CA表层固定的MZVI颗粒与Cr(Ⅵ)反应生成的(Fe_xCr_1-x)(OH)₃络合沉淀会冲破CA表层外壳,释放到零价铁-渗透反应墙(Fe⁰-PRB)系统中,导致PRB反应初期出现堵塞现象;大部分MZVI颗粒...     

Investigations of cell immobilization in alginate: rheological and electrostatic extrusion studies

In this study, the process of electrostatic extrusion as a method for cell immobilization was investigated. We have assessed the effects of concentrations of yeast cells (as a model cell type) and Na alginate on the size of the resulting microbeads and attempted to rationalize the obtained findings by rheological characterization of the cell–alginate suspensions. Under the investigated conditions, microbeads, 50–600 µm in diameter, were produced and the increase in both alginate and cell concentrations resulted in larger microbeads with their sizes having higher standard deviations. Rheological characterization revealed non‐Newtonian, pseudoplastic behavior of cell–alginate suspensions with higher viscosities at higher alginate concentrations. However, the presence of cells even at high concentrations (5 × 10⁸ and 1 × 10⁹ cells mL^?1) did not significantly affect the rheological properties of the Na alginate solution. Finally, we have investigated the kinetics of alginate gelation with respect to the quantity of Ca²⁺ ions and the presence of cells. The molar ratio of α‐L ‐guluronic acid units to Ca²⁺ ions of 4:1 provided complete crosslinking. The presence of cells decreased the rate of network formation as well as the strength of the obtained Ca alginate hydrogel. Copyright © 2006 Society of Chemical Industry     

Development of silver nanoparticles‐loaded calcium alginate beads embedded in gelatin scaffolds for use as wound dressings

Silver nanoparticles (AgNPs)‐loaded calcium alginate beads embedded in gelatin scaffolds were developed to sustain and maintain the release of silver (Ag⁺) ions over an extended time period. The UV irradiation technique was used to reduce Ag⁺ ions in alginate solution to AgNPs. The average sizes of AgNPs ranged between ca 20 and ca 22 nm. The AgNPs‐loaded calcium alginate beads were prepared by electrospraying of a sodium alginate solution containing AgNPs into calcium chloride (CaCl₂) solution. The AgNPs‐loaded calcium alginate beads were then embedded into gelatin scaffolds. The release characteristics of Ag⁺ ions from both the AgNPs‐loaded calcium alginate beads and the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were determined in either deionized water or phosphate buffer solution at 37 °C for 7 days. Moreover, the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were tested for their antibacterial activity and cytotoxicity. © 2014 Society of Chemical Industry     

Modelling of phenol biodegradation by Candida tropicalis immobilised in alginate gel beads

Phenol‐degrading yeast Candida tropicalis were immobilised in alginate gel beads and photographed by scanning electron microscopy. Batch phenol biodegradation experiments were done in shaking flasks under varying conditions such as initial phenol concentrations and bead loadings. A mathematical model was proposed to simulate the batch phenol biodegradation process in the immobilised system, which took into account the internal and external mass transfer resistances of phenol and oxygen and the double‐substrate phenol–oxygen intrinsic kinetics. The validation of this model was done by the comparison between the model simulations and the experimental measurements of phenol concentration profiles in the main liquid phase. Moreover, the time and radius courses of phenol, oxygen, and cell concentration profiles within the alginate gel beads were reasonably predicted by the proposed model.     

固定化血红蛋白催化去除废水中的五氯酚

以海藻酸钙胶囊固定活性炭和血红蛋白,研究了H2O2存在下其对水溶液中五氯酚的吸附催化去除作用。讨论了H2O2及五氯酚的初始浓度、血红蛋白固定量以及pH等对五氯酚去除率的影响。结果表明,当溶液的pH为7、H2O2浓度为8.5×10-4 mol/L、血红蛋白固定量为6.6×10-6 mol/L、反应温度为25℃,反应时间为280 min时,五氯酚去除率可达到81.8%,且固定化血红蛋白可被反复使用多次。     

海藻酸凝胶性质对蛋白质扩散的影响

通过观察冷冻干燥海藻酸凝胶的断面扫描电镜(SEM)照片与卵清蛋白从海藻酸凝胶中的释放试验,分析了海藻酸凝胶性质对蛋白质在凝胶中扩散的影响。凝胶的SEM照片可见,海藻酸钙的冷冻干燥颗粒内为较大的圆孔,海藻酸锌凝胶内为较小的长孔,表明海藻酸锌高分子链在凝胶颗粒中的体积分率相对较大同时刚性较强;卵清蛋白从海藻酸凝胶颗粒中释放的试验结果表明,由于上述海藻酸锌凝胶的特性,导致海藻酸锌对卵清蛋白扩散阻滞作用相对较强;根据试验数据计算得卵清蛋白在海藻酸钙、海藻酸锌凝胶颗粒中的扩散系数分别为1.19×10-7、0.07×10-7cm2/s,利用阻滞模型计算得海藻酸锌高分子链在凝胶颗粒中体积分率约为海藻酸钙高分子链在凝胶颗粒中体积分率的1.7倍。