共查询到20条相似文献,搜索用时 62 毫秒
1.
Song-Se Yi Jin-Mi Noh Yoon-Sik Lee 《Journal of Molecular Catalysis .B, Enzymatic》2009,57(1-4):123-129
Amino acid modified chitosan beads (CBs) for immobilization of lipases from Candida rugosa were prepared by activation of a chitosan backbone with epichlorohydrin followed by amino acid coupling. The beads were analyzed by elemental analysis and solid state NMR with coupling yields of the amino acids ranging from 15 to 60%. The immobilized lipase on unmodified chitosan beads showed the highest immobilization yield (92.7%), but its activity was relatively low (10.4%). However, in spite of low immobilization yields (15–50%), the immobilized lipases on the amino acid modified chitosan beads showed activities higher than that of the unmodified chitosan beads, especially on Ala or Leu modified chitosan beads (Ala-CB or Leu-CB) with 49% activity for Ala-CB and 51% for Leu-CB. The immobilized lipases on Ala-CB improved thermal stability at 55 °C, compared to free and immobilized lipases on unmodified chitosan beads and the immobilized lipase on Ala-CB retained 93% of the initial activity when stored at 4 °C for 4 weeks. In addition, the activity of the immobilized lipase on Ala-CB retained 77% of its high initial activity after 10 times of reuse. The kinetic data (kcat/Km) supports that the immobilized lipase on Ala-CB can give better substrate specificity than the unmodified chitosan beads. 相似文献
2.
Maria Benedetta Fadda Maria Rita Dessì Raffaele Maurici Augusto Rinaldi Giuseppe Satta 《Applied microbiology and biotechnology》1984,19(5):306-311
Summary A commercial preparation of cellulase was immobilized on CNBr-sepharose, ConA-sepharose, and CNBr-glass beads. When filter paper was used as the substrate, the specific activity of the enzyme immobilized on ConA-sepharose was more than twice that of the soluble enzyme, while the activity of the enzymes immobilized on the other two substrates was either very slightly (CNBr-sepharose) or slightly (CNBr-glass beads) reduced. The immobilized enzymes showed alterations both in the Km and V max values: these were generally either slightly increased (Km) or reduced (V max). In addition, the immobilized enzymes were more resistant to inhibition both by glucose and cellobiose, they were all more stable than the soluble enzyme and solubilized three different natural lignocellulosic materials (alfa-alfa, wheat straw, and pine needles) to a much greater or significantly greater extext than the soluble enzyme: the ConA-sepharose cellulase was the most efficient. The possibility of reusing the immobilized enzyme was also tested. It was found that the ConA-sepharose cellulase could be reused five times with a final loss of activity that ranged between 30% and 50%. 相似文献
3.
Vellore Sunder Avinash Palna Dinesh Chauhan Shraddha Gaikwad 《Preparative biochemistry & biotechnology》2017,47(1):52-57
The production of 6-aminopenicillanic acid (6-APA) is a key step in the manufacture of semisynthetic antibiotics in the pharmaceutical industry. The penicillin G acylase from Escherichia coli has long been utilized for this purpose. However, the use of penicillin V acylases (PVA) presents some advantages including better stability and higher conversion rates. The industrial application of PVAs has so far been limited due to the nonavailability of suitable bacterial strains and cost issues. In this study, whole-cell immobilization of a recombinant PVA enzyme from Pectobacterium atrosepticum expressed in E. coli was performed. Membrane permeabilization with detergent was used to enhance the cell-bound PVA activity, and the cells were encapsulated in calcium alginate beads and cross-linked with glutaraldehyde. Optimization of parameters for the biotransformation by immobilized cells showed that full conversion of pen V to 6-APA could be achieved within 1?hr at pH 5.0 and 35°C, till 4% (w/v) concentration of the substrate. The beads could be stored for 28 days at 4°C with minimal loss in activity and were reusable up to 10?cycles with 1-hr hardening in CaCl2 between each cycle. The high enzyme productivity of the PVA enzyme system makes a promising case for its application for 6-APA production in the industry. 相似文献
4.
Graphene oxide/chitosan and reduced graphene oxide/chitosan (GO/CS and RGO/CS) beads were prepared by precipitation with NaOH. Porcine liver esterase was immobilized on these beads to give GO/CS/E and RGO/CS/E beads. The optimum conditions for the maximum activity of RGO/CS/E beads were pH 8 and 50°C. The stability of the enzyme immobilized on GO/CS/E and RGO/CS/E was high in the pH range of 5–8. The GO/CS/E beads showed superior stability compared to that of the free enzyme and CS/E beads between 20 and 50°C. Kinetic analysis showed that GO/CS/E was a better catalyst than the RGO/CS/E beads with a lower Km value of 0.9?mM. The hybrid beads also retained more than 95% activity after 10 consecutive cycles. The GO/CS/E and RGO/CS/E beads retained 84% and 87% activity after 40 days at 4°C. The GO/CS/E beads were used for the successful hydrolysis of methyl 4-hydroxy benzoate. 相似文献
5.
Polymer-coated magnetic beads have become widely used in biological applications because of their facile recovery and easily
modifiable surface. Herein, we report the application of magnetic beads to in vitro refolding of B. cepacia lipase. Magnetic particles (Fe3O4) prepared by co-precipitation of Fe2+ and Fe3+ ions under basic conditions were subsequently coated with carboxylic acid-containing polystyrene by emulsion polymerization.
The polymer-coated magnetic beads were then conjugated with molecular chaperone proteins to assist with refolding. The chaperone-conjugated
magnetic beads efficiently refolded B. cepacia lipase and were easily reused. The beads showed comparable refolding activity to the soluble chaperone, and retained more
than 95% of their refolding activity after five cycles of refolding B. cepacia lipase. 相似文献
6.
Kunio Ohmiya Chisako Terao Shoichi Shimizu Takeshi Kobayashi 《Bioscience, biotechnology, and biochemistry》2013,77(2):491-498
β-Galactosidase from Aspergillus oryzae was immobilized in crosslinked polyacrylamide gel beads. The presence of the enzyme inhibitor, such as glucono-δ-lactone or galactono-γ-lactone, during polymerization procedure enhanced the residual enzymatic activity in the polymer beads, and activity yield attained up to 45%. Such enhancement effect was also observed when bovine serum albumin, dithiothreitol or glutathione was added during polymerization. Temperature and pH optima were not affected by the immobilization. The Michaelis constants for free and immobilized β-galactosidase were comparable. Lyophilized beads exhibited good stability without loss of enzymatic activity when stored at 4°C for 47 days. 相似文献
7.
Li YG Xing JM Xiong XC Li WL Gao HS Liu HZ 《Journal of industrial microbiology & biotechnology》2008,35(3):145-150
The immobilization of Pseudomonas delafieldii R-8 in calcium alginate beads has been studied in order to improve biodesulfurization activity in oil/water (O/W) biphasic
systems. A gas jet extrusion technique was performed to produce immobilized beads. The specific desulfurization rate of 1.5 mm
diameter beads was 1.4-fold higher than that of 4.0 mm. Some nonionic surfactants can significantly increase the activity
of immobilized cells. The desulfurization rate with the addition of 0.5% Span 80 increased 1.8-fold compared with that of
the untreated beads. The rate of biodesulfurization was markedly enhanced by decreasing the size of alginate beads and adding
the surfactant Span 80, most likely resulting from the increasing mass transfer of substrate to gel matrix. 相似文献
8.
Enhancement and stabilization of the production of glucoamylase by immobilized cells of Aureobasidium pullulans in a fluidized-bed reactor 总被引:1,自引:0,他引:1
Federico Federici Maurizio Petruccioli Martin W. Miller 《Applied microbiology and biotechnology》1990,33(4):407-409
Summary Glucoamylase production by Aureobasidium pollulans A-124 was compared in free-living cells, cells immobilized in calcium alginate gel beads aerated on a rotary shaker (agitation rate 150 rpm), and immobilized cells aerated in an air bubble column reactor. Fermentation conditions in the bioreactor were established for bead concentration, substrate (starch) concentration, calcium chloride addition to the fermentation medium, and rate of aeration. Production of glucoamylase was optimized at approximately 1.5 units of enzyme activity/ml medium in the bioreactor under the following conditions: aeration rate, 2.0 vol air per working volume of the bioreactor (280 ml) per minute; gel bead concentration, 30% of the working volume; substrate (starch) concentration, at 0.3% (w/v); addition of calcium chloride to the medium at a final concentration of 0.01 M. Productivity levels were stabilized through the equivalent of ten batches of medium with the original inoculum of immobilized beads.
Offprint requests to: M. Petruccioli 相似文献
9.
Kati Réczey Ingrid Persson Folke Tjerneld Bärbel Hahn-Hägerdal 《Biotechnology Techniques》1989,3(3):205-210
Summary
Aspergillus phoenicis QM 329 was found to grow in the shape of beads in shake flasks and in an air-lift fermentor. Initial culture pH, pH profile during cultivation, carbon source, inoculum size and fermentor configuration influenced the retainment of the -glucosidase activty in the mycelium. Glucose and soluble starch produced beads with the highest activity and the best stability. Glucose-derived beads were more homogeneous in size and shape than the starch-derived beads. These beads kept their integrity for 10 d at 50° C. After 48 h hydrolysis of 50 g/l cellobiose 75% of the initial enzyme activity remained. The beads could be air-dried and alcohol-sterilized with only minor loss of activity. The size of the beads could be controlled by varying the size of the conidia inoculum. In an air-lift fermentor with a working volume of 1500 ml,900 ml beads with an average diameter of 2 mm (estimated to 37–45,000 beads) were produced in less than 3 d with glucose as carbon source. The beads held a -glucosidase activity of 0.140 IU/bead determined with the pNP assay. 相似文献
10.
Pallavi Tripathi Arpana Kumari Parthasarthi Rath Arvind M. Kayastha 《Journal of Molecular Catalysis .B, Enzymatic》2007,49(1-4):69-74
α-Amylase from mung beans (Vigna radiata) was immobilized on two different matrices, Amberlite MB 150 and chitosan beads. Maximum immobilization obtained was 72% and 69% in case of Amberlite and chitosan beads, respectively. The pH optima of soluble α-amylase were 5.6, whereas that for immobilized amylase on chitosan and Amberlite was 7.0. Soluble amylase and Amberlite immobilized amylase showed maximum activity at 65 °C, whereas chitosan immobilized amylase showed maximum activity at 75 °C. α-Amylase immobilized on Amberlite showed apparent Km of 2.77 mg/ml, whereas α-amylase immobilized on chitosan showed an apparent Km of 5 mg/ml. The Amberlite-amylase and chitosan-amylase showed a residual activity of 43% and 27%, respectively, after 10 uses. The loss of activity for free amylase after 100 days of storage at 4 °C was 70%, whereas that for Amberlite- and chitosan-amylases, under the same experimental conditions, the losses were 45% and 55%, respectively. The easy availability of mung bean α-amylase, the ease of its immobilization on low-cost matrices and good stability upon immobilization in the present study makes it a suitable product for further use in industrial applications. 相似文献
11.
Johannes Tramper Franz Müller Henk C. Van Der Plas 《Biotechnology and bioengineering》1978,20(10):1507-1522
Milk xanthine oxidase was immobilized by covalent attachment to CNBr-activated Sepharose 4B and by adsorption to n-octylamine-substituted Sepharose 4B. The amounts of activity immobilized for the two preparations were 30 and 90%, respectively. The pH optima for free and adsorbed xanthine oxidase were at 8.6 and 8.2, respectively. Both free and immobilized xanthine oxidase show substrate inhibition. The apparent inhibition constant (Ki′) found for adsorbed xanthine oxidase with xanthine as substrate was higher than the Ki for the free enzyme, which was shown to be due to substrate diffusion limitation in the pores of the carrier beads (internal diffusion limitation). Higher substrate concentrations, as desirable for practical application in organic synthesis, can therefore be used with the immobilized enzyme without decreasing the rate. As a result of the internal diffusion limitation the apparent Michaelis constant (Km′) for adsorbed xanthine oxidase was also higher than the Km for the free enzyme. Immobilized xanthine oxidase was more stable than the free enzyme during storage at 4 and 30°C. Both forms rapidly lost activity during catalysis. The loss was proportional to the amount of substrate converted. Coimmobilization of xanthine oxidase with superoxide dismutase and catalase improved the operational stability, suggesting that O2? and H2O2 side-products of the enzymatic reaction were involved in the inactivation. Coimmobilization with albumin also had some stabilizing effect. Complete surrounding of xanthine oxidase by protein, however, by means of etrapment in a glutaraldehyde-crosslinked gelatin matrix, considerably enhanced the operational half-life. This system was less efficient than the Sepharose preparations either because much activity was lost during the immobilization procedure and/or because it had poor flow properties. Xanthine (15 mg)was converted by an adsorbed xanthine oxidase preparation and product (uric acid) was isolated in high yield (84%). 相似文献
12.
Polyhydroxyalkanoate (PHA) beads, recombinantly produced in Escherichia coli, were functionalized to display lipase B from Candida antarctica as translational protein fusion. The respective beads were characterized in respect to protein content, functionality, long term storage capacity and re-usability. The direct fusion of the PHA synthase, PhaC, to lipase B yielded active PHA lipase beads capable of hydrolyzing glycerol tributyrate. Lipase B beads showed stable activity over several weeks and re-usability without loss of function. 相似文献
13.
Microsomes from grapewine (V. vinifera L. cv. Camay Fréaux) cell homogenates were immobilized in calcium alginate beads. Cinnamic acid-4-hydroxylase activities for both freely suspended and immobilized microsomes were compared, resulting in a decrease of 30–40% of the initial activity as a consequence of immobilization. This decrease was probably due to both protein denaturation and microsomal mass losses during the gelation process. Nevertheless, immobilized microsomes showed an enhanced thermostability. Only 35% of the initial activity was lost when immobilized microsomes were incubated at 45°C for 10 minutes, whereas a 68% activity loss was observed when dealing with free microsomes. 相似文献
14.
In this study, we developed a packed-bed immobilized cell reactor containing active β-gal (β-galactosidase) inclusion body
(IB)-containing Escherichia coli (E. coli) cells in alginate beads. This packed-bed reactor was operated using a substrate feed solution 0.72 ∼ 38.4 mM ONPG (o-nitrophenyl-β-D-galactoside) prepared in Z buffer supplemented with chloroform and 0.1% SDS (sodium dodecyl sulfate). The
production rate of ONP (o-nitrophenol) in the reactor containing cells that were incubated with α-MG (α-methyl D-glucospyranoside)
or D-fucose after induction was superior to those prepared with cells that were not incubated with α-MG or D-fucose. The ONP
production rate was increased proportionally with ONPG concentration in the substrate feed up to a concentration of 38.4 mM.
However, as the ONPG concentration was increased in the substrate feed solution, galactose inhibition inside the alginate
beads was increased. This most likely occurred due to problems with diffusion. In addition, partial breakage of alginate beads
was observed during the later periods of operation. In this study, we demonstrated that active β-gal IB-containing E. coli cells were sustained in the immobilized cell reactor during operation. Particularly, these findings demonstrate the feasibility
of using active IBs in an enzymatic reaction without the need for any purification step. In addition, we showed that these
IB-containing cells could be directly used in an immobilized reactor. 相似文献
15.
16.
《Process Biochemistry》2014,49(5):840-844
The effective system of reusing mycelial fructosyltransferase (FTase) immobilized with two polymers, chitosan and alginate were evaluated for continuous production of fructooligosaccharides (FOS). The alginate beads were successfully developed by maintaining spherical conformation of using 0.3% (w/v) sodium alginate with 0.1% (w/v) of CaCl2 solution for highest transfructosylating activity. The characteristics of free and immobilized FTase were investigated and results showed that optimum pH and temperature of FTase activity were altered by immobilized materials. A successive production of FOS by FTase entrapped alginate beads was observed at an average of 62.96% (w/w) up to 7 days without much losing its activity. The data revealed by HPLC analysis culminate 67.75% (w/w) of FOS formation by FTase entrapped alginate beads and 42.79% (w/w) by chitosan beads in 36 h of enzyme substrate reaction. 相似文献
17.
Bayramoglu G Karagoz B Altintas B Arica MY Bicak N 《Bioprocess and biosystems engineering》2011,34(6):735-746
Fibrous poly(styrene-b-glycidylmethacrylate) brushes were grafted on poly(styrene–divinylbenzene) (P(S–DVB)) beads using surface-initiated atom
transfer radical polymerization. Tetraethyldiethylenetriamine (TEDETA) ligand was incorporated on P(GMA) block. The ligand
attached beads were used for reversible immobilization of lipase. The influences of pH, ionic strength, and initial lipase
concentration on the immobilization capacities of the beads have been investigated. Lipase adsorption capacity of the beads
was about 78.1 mg/g beads at pH 6.0. The K
m value for immobilized lipase was about 2.1-fold higher than that of free enzyme. The thermal, and storage stability of the
immobilized lipase also was increased compared to the native lipase. It was observed that the same support enzyme could be
repeatedly used for immobilization of lipase after regeneration without significant loss in adsorption capacity or enzyme
activity. A lipase from Mucor miehei immobilized on styrene–divinylbenzene copolymer was used to catalyze the direct esterification of butyl alcohol and butyric
acid. 相似文献
18.
Saccharomyces cerevisiae cells were immobilized in calcium alginate beads for use in the continuous production of ethanol. Yeasts were grown in medium supplemented with ethanol to selectively screen for a culture which showed the greatest tolerance to ethanol inhibition. Yeast beads were produced from a yeast slurry containing 1.5% alginate (w/v) which was added as drops to 0.05M CaCl2 solution. To determine their optimum fermentation parameters, ethanol production using glucose as a substrate was monitored in batch systems at varying physiological conditions (temperature, pH, ethanol concentration), cell densities, and gel concentration. The data obtained were compared to optimum free cell ethanol fermentation parameters. The immobilized yeast cells examined in a packed-bed reactor system operated under optimized parameters derived from batch-immobilized yeast cell experiments. Ethanol production rates, as well as residual sugar concentration were monitored at different feedstock flow rates. 相似文献
19.
Heribert Keweloh Hermann-Josef Heipieper Hans-Jürgen Rehm 《Applied microbiology and biotechnology》1989,31(4):383-389
Summary The antibacterial activity of phenol was determined by measuring inhibition of exponentially growing free and immobilized cells of Escherichia coli, Pseudomonas putida and Staphylococcus aureus. Immobilization of microorganisms in calcium alginate beads reduced the growth inhibition caused by bacteriostatic concentrations of phenol. The increase in phenol tolerance occurred at different culture conditions and growth rates of the cells. The strength of the effect, however, was found to correlate with the formation of colonies in the gel matrix. Dissolution of gel beads led to a substantial loss of the protection against phenol of immobilized-grown cells. 相似文献
20.
G Zayed 《Journal of industrial microbiology & biotechnology》1997,19(1):39-42
Among three esters of p-hydroxybenzoate, n-butyl p-hydroxybenzoate was selected as the best antimicrobial substance. Molasses medium sterilized by this ester was used as
a substrate for ethanol production. n-Butyl p-hydroxybenzoate (0.15% w/v) completely inhibited the growth of free yeast cell inoculum, Ca-alginate immobilized yeast
inoculum and bacterial contaminants. Immobilization of the yeast cell inoculum in Ca-alginate with castor oil (6% v/v) offered
a yeast cell protection against the inhibitory effect of n-butyl p-hydroxybenzoate. The presence of castor oil in this immobilization system did not affect the metabolic activity of the yeast
in beads compared to the cells immobilized without castor oil. The yeast cell beads in this system completely utilized up
to 25% molasses sugar with an ethanol yield of 10.58%, equal to 83% of its theoretical value. The beads were stable and
could be used successfully for seven cycles of batch fermentation. The optimum fermentation temperature using this system
was 35°C.
Received 21 January 1997/ Accepted in revised form 05 May 1997 相似文献