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41.
Response surface methodology (RSM) and centre composite design (CCD) were used to optimize immobilization of β-galactosidase (BGAL) from Pisum sativum onto two matrices: Sephadex G-75 and chitosan beads. The immobilization efficiency of 75.66% and 75.19% were achieved with Sephadex G-75 and chitosan, respectively. There was broad divergence in physico-chemical properties of Sephadex-PsBGAL and chitosan-PsBGAL. Chitosan-PsBGAL was better suited for industrial application based on its broad pH and temperature optima, higher temperature stability, reusability etc. Sephadex-PsBGAL and chitosan-PsBGAL showed much variation in their catalytic properties with respect to soluble enzyme. About 50% loss in activity of Sephadex-PsBGAL and chitosan-PsBGAL were observed after 12 and 46 days at 4 °C, respectively. Chitosan-PsBGAL showed higher rate of lactose hydrolysis present in milk and whey at room temperature and 4 °C than Sephadex-PsBGAL. In both cases, lactose of milk whey was hydrolyzed at higher rate than that of milk. 相似文献
42.
利用基因工程菌HC01固定化细胞转化生产D-对羟基苯甘氨酸 总被引:1,自引:0,他引:1
对一菌两酶工程菌HC01转化底物DL-对羟基苯海因(DL-HPH)的最适条件及其细胞固定化进行了研究,HC01游离细胞转化DL-HPH的最适条件为40°C、pH7.5。通过对固定化细胞酶活力测定,确定细胞固定化的最优条件为海藻酸钠浓度2.5%、细胞浓度0.029g/mL、钙离子浓度3%。固定化HC01的热稳定性比游离细胞高5°C,二价金属离子Mn2+、Mg2+、Cu2+、Co2+和Ni2+在浓度为0.1mmol/L时对固定化细胞中D-海因酶(HYD)和N-氨甲酰-D-氨基酸酰胺水解酶(CAB)两酶的活力无显著影响,Mn2+和Mg2+可分别使游离细胞中CAB活力提高至原来的2.1和2.7倍。在氮气保护下,当初始pH为9.0、转化温度为40°C、转速为80r/min,利用固定化HC01转化30g/L的DL-HPH时,36h后转化率可达97%左右,产物D-HPG经纯化后光学纯度达到99.7%,得率可达85%。 相似文献
43.
Zhichao Pei Henrik Anderson Annica Myrskog Gunnar Dunér Teodor Aastrup 《Analytical biochemistry》2010,398(2):161-210
The performance of immunosensors is highly dependent on the amount of immobilized antibodies and their remaining antigen binding capacity. In this work, a method for immobilization of antibodies on a two-dimensional carboxyl surface has been optimized using quartz crystal microbalance biosensors. We show that successful immobilization is highly dependent on surface pKa, antibody pI, and pH of immobilization buffer. By the use of EDC/sulfo-NHS (1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysulfosuccinimide) activation reagents, the effect of the intrinsic surface pKa is avoided and immobilization at very low pH is therefore possible, and this is important for immobilization of acidic proteins. Antigen binding capacity as a function of immobilization pH was studied. In most cases, the antigen binding capacity followed the immobilization response. However, the antigen-to-antibody binding ratio differed between the antibodies investigated, and for one of the antibodies the antigen binding capacity was significantly lower than expected from immobilization in a certain pH range. Tests with anti-Fc and anti-Fab2 antibodies on different antibody surfaces indicated that the orientation of the antibodies on the surface had a profound effect on the antigen binding capacity of the immobilized antibodies. 相似文献
44.
Carla Silva Carla Joana Silva Andrea Zille Georg M. Guebitz Artur Cavaco-Paulo 《Enzyme and microbial technology》2007,41(6-7):867-875
Polyamide matrices, such as membranes, gels and non-wovens, have been applied as supports for enzyme immobilization, although in literature the enzyme immobilization on woven nylon matrices is rarely reported. In this work, a protocol for a Trametes hirsuta laccase immobilization using woven polyamide 6,6 (nylon) was developed. A 24 full factorial design was used to study the influence of pH, spacer (1,6-hexanediamine), enzyme and crosslinker concentration on the efficiency of immobilization. The factors enzyme dosage and spacer seem to have played a critical role in the immobilization of laccase onto nylon support. Under optimized working conditions (29 U mL−1 of laccase, 10% of glutaraldehyde, pH = 5.5, with the presence of the spacer), the half-life time attained was about 78 h (18% higher than that of free enzyme), the protein retention was 30% and the immobilization yield was 2%. The immobilized laccase has potential for application in the continuous decolourization of textile effluents, where it can be applied into a membrane reactor. 相似文献
45.
Pectinase was immobilized on a sodium alginate support using glutaraldehyde and retained 66% activity. The optimal pH for
activity shifted from 3.0 to 3.5 after immobilization; however, the optimum temperature remained unchanged at 40°C. The immobilized
enzyme also had a higher thermal stability and reusability than the free enzyme, and retained 80% of initial activity after
11 batch reactions. 相似文献
46.
Mineralization of diuron has not been previously demonstrated despite the availability of some bacteria to degrade diuron
into 3,4-dichloroaniline (3,4-DCA) and others that can mineralize 3,4-DCA. A bacterial co-culture of Arthrobacter sp. N4 and Delftia acidovorans W34, which respectively degraded diuron (20 mg l−1) to 3,4-DCA and mineralized 3,4-DCA, were able to mineralize diuron. Total diuron mineralization (20 mg l−1) was achieved with free cells in co-culture. When the bacteria were immobilized (either one bacteria or both), the degradation
rate was higher. Best results were obtained with free Arthrobacter sp. N4 cells co-cultivated with immobilized cells of D. acidovorans W34 (mineralization of diuron in 96 h, i.e., 0.21 mg l−1 h−1 vs. 0.06 mg l−1 h−1 with free cells in co-culture). 相似文献
47.
Lactic acid is a versatile organic acid, which finds major application in the food, pharmaceuticals, and chemical industries.
Microbial fermentation has the advantage that by choosing a strain of lactic acid bacteria producing only one of the isomers,
an optically pure product can be obtained. The production of l(+) lactic acid is of significant importance from nutritional viewpoint and finds greater use in food industry. In view of
economic significance of immobilization technology over the free-cell system, immobilized preparation of Lactobacillus casei was employed in the present investigation to produce l(+) lactic acid from whey medium. The process conditions for the immobilization of this bacterium using calcium pectate gel
were optimized, and the developed cell system was found stable during whey fermentation to lactic acid. A high lactose conversion
(94.37%) to lactic acid (32.95 g/l) was achieved with the developed immobilized system. The long-term viability of the pectate-entrapped
bacterial cells was tested by reusing the immobilized bacterial biomass, and the entrapped bacterial cells showed no decrease
in lactose conversion to lactic acid up to 16 batches, which proved its high stability and potential for commercial application. 相似文献
48.
Limbut W Loyprasert S Thammakhet C Thavarungkul P Tuantranont A Asawatreratanakul P Limsakul C Wongkittisuksa B Kanatharana P 《Biosensors & bioelectronics》2007,22(12):3064-3071
A microfluidic conductimetric bioreactor has been developed. Enzyme was immobilized in the microfluidic channel on poly-dimethylsiloxane (PDMS) surface via covalent binding method. The detection unit consisted of two gold electrodes and a laboratory-built conductimetric transducer to monitor the increase in the conductivity of the solution due to the change of the charges generated by the enzyme-substrate catalytic reaction. Urea–urease was used as a representative analyte-enzyme system. Under optimum conditions urea could be determined with a detection limit of 0.09 mM and linearity in the range of 0.1–10 mM (r = 0.9944). The immobilized urease on the microchannel chip provided good stability (>30 days of operation time) and good repeatability with an R.S.D. lower than 2.3%. Good agreement was obtained when urea concentrations of human serum samples determined by the microfluidic flow injection conductimetric bioreactor system were compared to those obtained using the Berthelot reaction (P < 0.05). After prolong use the immobilized enzyme could be removed from the PDMS microchannel chip enabling new active enzyme to be immobilized and the chip to be reused. 相似文献
49.
Extracellular exoinulinase from Kluyveromyces marxianus YS-1, which hydrolyzes inulin into fructose, was immobilized on Duolite A568 after partial purification by ethanol precipitation
and gel exclusion chromatography on Sephadex G-100. Optimum temperature of immobilized enzyme was 55 °C, which was 5 °C higher
than the free enzyme and optimal pH was 5.5. Immobilized biocatalyst retained more than 90% of its original activity after
incubation at 60 °C for 3 h, whereas in free form its activity was reduced to 10% under same conditions, showing a significant
improvement in the thermal stability of the biocatalyst after immobilization. Apparent K
m values for inulin, raffinose and sucrose were found to be 3.75, 28.5 and 30.7 mM, respectively. Activation energy (E
a) of the immobilized biocatalyst was found to be 46.8 kJ/mol. Metal ions like Co2+ and Mn2+ enhanced the activity, whereas Hg2+ and Ag2+ were found to be potent inhibitors even at lower concentrations of 1 mM. Immobilized biocatalyst was effectively used in
batch preparation of high fructose syrup from Asparagus racemosus raw inulin and pure inulin, which yielded 39.2 and 40.2 g/L of fructose in 4 h; it was 85.5 and 92.6% of total reducing sugars
produced, respectively. 相似文献
50.
We report an experimental procedure that results in the immobilization of the motile Tetraselmis in an alginate bead, thereby providing clonal populations for ultrastructure research and greatly facilitating transmission
electron microscope (TEM) studies. The Prasinophyte Tetraselmis CS317, which is a potential candidate species for aquaculture, was used in our study. The cells were immobilized in Ca-alginate
beads and allowed to grow within the beads for 2 weeks. Each cell in the bead divided repeatedly, resulting in a dense clonal
population which could be easily distinguished under a compound microscope. Portions of the Tetraselmis-alginate beads containing the clonal populations were then used for TEM processing for a fine structure study without the
need for centrifugation. The normal TEM processing of microalgae by repeated centrifugations during processing or a centrifugation-agar
embedding mixture is very time consuming and unreliable due to the nature of the agar and, in the case of the motile Tetraselmis, the force of centrifugation required to sediment the cells. Our results revealed that the alginate did not interfere with
the fixation, embedding and sectioning, and the cells appeared to possess all of the structural characteristics of Tetraselmis cells, including the flagella apparatus. We conclude that immobilized Tetraselmis in alginate provides a simple experimental system for ultrastructural research.
Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines. 相似文献