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1.
Isomaltulose was obtained from sucrose solution by immobilized cells of Erwinia sp. D12 using a batch and a continuous process. Parameters for sucrose conversion into isomaltulose were evaluated using
both experimental design and response surface methodology. Erwinia sp. D12 cells were immobilized in different alginates, and the influence of substrate flow rate and concentration parameters
to produce isomaltulose from sucrose were observed. Response surface methodology demonstrated that packed bed columns containing
cells immobilized in low-viscosity sodium alginate (250 cP) presented a mean isomaltulose conversion rate of 47%. In a continuous
process, both sucrose substrate concentration and substrate flow rate parameters had a significant effect (p < 0.05) and influenced the conversion of sucrose into isomaltulose. Higher conversion rates of sucrose into isomaltulose,
from 53–75% were obtained using 75 g of immobilized cells at a substrate flow rate of 0.6 mL/min. 相似文献
2.
Sushovan Chatterjee Lepakshi Barbora Swaranjit Singh Cameotra Pinakeswar Mahanta Pranab Goswami 《Applied biochemistry and biotechnology》2009,157(3):593-600
Lipase was immobilized in silk fibers through glutaraldehyde cross-linking to a maximum loading of 59 U/g silk-fiber and the
immobilized lipase was utilized for the hydrolysis of sunflower oil (Helianthus annuus). The hydrolytic activity of the lipase, which was poor in biphasic oil in water system, was increased significantly when
the sunflower oil was emulsified in aqueous medium. The hydrolytic activities of the immobilized lipase were 48.73 ± 1.26 U,
36.11 ± 0.96 U, and nil when the substrate sunflower oil was used as emulsion created by a rhamnolipid biosurfactant, Triton
X100, and ultrasonication, respectively. Although the efficiency of the immobilized lipase was less than 12% than the corresponding
free lipase, the immobilized lipase could be reused for the biosurfactant-mediated hydrolysis of sunflower oil up to third
cycle of the reaction. The yield of the fatty acids in the second, third, and fourth cycles were 49.45%, 22.91%, and 5.09%,
respectively, of the yield obtained in the first cycle. 相似文献
3.
Pereira Ernandes B. de Castro Heizir F. De Moraes Flávio F. Zanin Gisella M. 《Applied biochemistry and biotechnology》2002,98(1-9):977-986
Microbial lipase from Candida rugosa immobilized into porous chitosan beads was tested for esterification selectivity with butanol and different organic acids
(C2–C12), and butyric acid and different aliphatic alcohols (C2–C10). After 24 h, the acids tested achieved conversions of
about 40–45%. Acetic acid was the only exception, and in this case butanol was not consumed. Different alcohols led to butyric
acid conversions >40%, except for ethanol, in which case butyric acid was converted only 26%. The system’s butanol and butyric
acid were selected for a detailed study by employing an experimental design. The influence of temperature, initial catalyst
concentration, and acid:alcohol molar ratio on the formation of butyl butyrate was simultaneously investigated, employing
a 23 full factorial design. The range studied was 37–50°C for temperature (X1), 1.25–2.5% (w/v) for the catalyst concentration (X2), and 1 and 2 for the acid:alcohol molar ratio (X3). Catalyst concentration (X2) was found to be the most significant factor and its influence was positive. Maximum ester yield (83%) could be obtained
when working at the lowest level for temperature (37°C), highest level for lipase concentration (2.5% [w/v]), and center level
of acid:alcohol molar ratio (1.5). The immobilized lipase was also used repeatedly in batch esterification reactions of butanol
with butyric acid, revealing a half-life of 86 h. 相似文献
4.
Hui-da Wan Shi-yu Sun Xue-yi Hu Yong-mei Xia 《Applied biochemistry and biotechnology》2012,166(6):1454-1462
Microwave has nonthermal effects on enzymatic reactions, mainly caused by the polarities of the solvents and substrates. In
this experiment, a model reaction with caprylic acid and butanol that was catalyzed by lipase from Mucor miehei in alkanes or arenes was employed to investigate the nonthermal effect in nonaqueous enzymatic esterification. With the comparison
of the esterification carried by conventional heating and consecutive microwave irradiation, the positive nonthermal effect
on the initial reaction rates was found substrate concentration-dependent and could be vanished ostensibly when the substrate
concentration was over 2.0 mol L−1. The polar parameter log P well correlates the solvent polarity with the microwave effect, comparing to dielectric constant and assayed solvatochromic
solvent polarity parameters. The log P rule presented in conventional heating-enzymatic esterification still fits in the microwaved enzymatic esterification. Alkanes
or arenes with higher log P provided positive nonthermal effect in the range of 2 ≤ log P ≤ 4, but yielded a dramatic decrement after log P = 4. Isomers of same log P with higher dielectric constant received stronger positive nonthermal effect. With lower substrate concentration, the total
log P of the reaction mixture has no obvious functional relation with the microwave effect. 相似文献
5.
Enzymatic regioselective acylation of 5-azacytidine with vinyl laurate was successfully conducted with an immobilized lipase
from Candida antarctica type B (i.e., Novozym 435) for the first time. The acylation of 5-azacytidine took place at its primary hydroxyl group and
the desired product 5′-O
-lauroyl-5-azacytidine could be prepared with high reaction rate, high conversion, and excellent regioselectivity. The influences
of several key variables on the enzymatic acylation were also systematically examined. Pyridine was found to be the best reaction
medium. The optimum initial water activity, the molar ratio of vinyl laurate to 5-azacytidine and reaction temperature were
0.07, 30:1, and 50 °C, respectively. Under the optimized conditions described above, the initial reaction rate, the substrate
conversion, and the regioselectivity were as high as 0.58 mM/min, 95.5%, and >99%, respectively, after a reaction time of
around 5 h. 相似文献
6.
Production of biodiesel from pure oils through chemical conversion may not be applicable to waste oils/fats. Therefore, enzymatic
conversion using immobilized lipase based on Rhizopus orzyae is considered in this article. This article studies this technological process, focusing on optimization of several process
parameters, including the molar ratio of methanol to waste oils, biocatalyst load, and adding method, reaction temperature,
and water content. The results indicate that methanol/oils ratio of 4, immobilized lipase/oils of 30 wt% and 40°C are suitable
for waste oils under 1 atm. The irreversible inactivation of the lipase is presumed, and a stepwise addition of methanol to
reduce inactivation of immobilized lipases is proposed. Under the optimum conditions the yield of methyl esters is around
88–90%. 相似文献
7.
In this study, the immobilized lipase was prepared by fabric membrane adsorption in fermentation broth. The lipase immobilization
method in fermentation broth was optimized on broth activity units and pH adjustments. The viscose fermentation broth can
be used with a certain percentage of dilution based on the original broth activity units. The fermentation broth can be processed
directly without pH adjustment. In addition, the oleic acid ethyl ester production in solvent-free system catalyzed by the
immobilized lipase was optimized. The molar ratio of ethanol to oil acid, the enzyme amount, the molecular amount, and the
temperature were 1:1, 12% (w/w), 9% (w/w)(based the total amount of reaction mixture), and 30 °C, respectively. Finally, the
optimal condition afforded at least 19 reuse numbers with esterification rate above 80% under stepwise addition of ethanol.
Due to simple lipase immobilization preparation, acceptable esterification result during long-time batch reactions and lower
cost; the whole process was suitable for industrial ethyl oleate production. 相似文献
8.
《Arabian Journal of Chemistry》2014,7(6):1159-1165
The ability of Candida cylindracea lipase produced using palm oil mill effluent (POME) as a basal medium to catalyze the esterification reaction for butyl butyrate formation was investigated. Butyric acid and n-butanol were used as substrates at different molar ratios. Different conversion yields were observed according to the affinity of the produced lipase toward the substrates. The n-butanol to butyric acid molar ratio of 8 and lipase concentration of 75 U/mg gave the highest butyl butyrate formation of 63.33% based on the statistical optimization using face centered central composite design (FCCCD) after 12 h reaction. The esterification potential of the POME based lipase when compared with the commercial lipase from the same strain using the optimum levels was found to show a similar pattern. It can be concluded therefore that the produced lipase possesses appropriate characteristics to be used as a biocatalyst in the esterification reactions for butyl butyrate formation. 相似文献
9.
A new process for enzymatic synthesis of biodiesel at high water content (10–20%) with 96% conversion by lipase from Candida sp. 99–125 was studied. The lipase, a no-position-specific lipase, was immobilized by a cheap cotton membrane and the membrane-immobilized
lipase could be used at least six times with high conversion. The immobilized lipase could be used for different oil conversion
and preferred unsaturated fatty acids such as oleic acid to staturated fatty acids such as palmitic acid. The changes in concentration
of fatty acids, diglycerides, and methyl esters in the reaction were studied and a mechanism of synthesis of biodiesel was
suggested: the triglycerides are first enzymatically hydrolyzed into fatty acids, and then these fatty acids are further converted
into methyl esters. 相似文献
10.
Yi Wang Jian Zhao Jian-He Xu Li-Qiang Fan Su-Xia Li Li-Li Zhao Xiao-Bo Mao 《Applied biochemistry and biotechnology》2010,162(8):2387-2399
A lipase gene from Serratia marcescens ECU1010 was cloned into expression vector pET28a, sequenced, and overexpressed as an N terminus His-tag fusion protein in
Escherichia coli. Through the optimization of culture conditions in shake flask, the lipase activity was improved up to 1.09 × 105 U/l, which is a great improvement compared to our previous reports. It was purified to homogeneity by Ni-NTA affinity chromatography
with an overall yield of 59.4% and a purification factor of 2.4-fold. This recombinant lipase displayed excellent stability
below 30 °C and within the pH range of 5.0−6.8, giving temperature and pH optima at 40 °C and pH 9.0, respectively. The lipase
activity was found to increase in the presence of metal ions such as Ca2+, Cu2+, and some nonionic surfactants such as PEG series. In addition, among p-nitrophenyl esters of fatty acids with varied chain length, the recombinant lipase showed the maximum activity on p-nitrophenyl laurate (C12). Using racemic trans-3-(4′-methoxy-phenyl)-glycidyl methyl ester [(±)-MPGM] as substrate, which is a key chiral synthon for production of diltiazem,
a 50% conversion yield was achieved after 4 h in toluene–water (100 mM KPB phosphate buffer, pH 7.5) biphasic system (5:5 ml)
at 30 °C under shaking condition (160 rpm), affording (−)-MPGM in nearly 100% ee. The K
m and V
max values of the lipase for (±)-MPGM were 222 mM and 1.24 mmol min−1 mg−1, respectively. The above-mentioned features make the highly enantioselective lipase from Serratia marcescens ECU1010 a robust biocatalyst for practical use in large-scale production of diltiazem intermediate. 相似文献
11.
Alexsandra Valério Karina G. Fiametti Suzimara Rovani Helen Treichel Débora de Oliveira J. Vladimir Oliveira 《Applied biochemistry and biotechnology》2010,160(6):1789-1796
The aim of this work is to report the production of mono- and diglycerides from olive oil at ambient condition and in pressurized
n-butane as solvent medium. For this purpose, a commercial immobilized lipase (Novozym 435) was employed as catalyst and sodium
(bis-2-ethyl-hexyl) sulfosuccinate (Aerosol-OT or AOT) as surfactant. The experiments were conducted in batch mode varying
the temperature, pressure, and AOT concentration. Results showed that lipase-catalyzed glycerolysis either with compressed
n-butane or in solvent-free system with AOT as surfactant might be a potential alternative route to conventional methods, as
high contents of reaction products, especially monoglycerides (∼ 60 wt.%), were achieved at mild temperature and pressure
with a relatively low solvent to substrates mass ratio (4:1) in short reaction times (2 h). 相似文献
12.
Ariela Veloso de Paula Gisele Fátima Morais Nunes Josiane de Lourdes Silva Heizir Ferreira de Castro Júlio César dos Santos 《Applied biochemistry and biotechnology》2010,160(4):1146-1156
Seven food grade commercially available lipases were immobilized by covalent binding on polysiloxane–polyvinyl alcohol (POS-PVA)
hybrid composite and screened to mediate reactions of industrial interest. The synthesis of butyl butyrate and the interesterification
of tripalmitin with triolein were chosen as model reactions. The highest esterification activity (240.63 μM/g min) was achieved
by Candida rugosa lipase, while the highest interesterification yield (31%, in 72 h) was achieved by lipase from Rhizopus oryzae, with the production of about 15 mM of the triglycerides C50 and C52. This lipase also showed a good performance in butyl butyrate synthesis, with an esterification activity of 171.14 μM/g min.
The results demonstrated the feasibility of using lipases from C. rugosa for esterification and R. oryzae lipase for both esterification and interesterification reactions. 相似文献
13.
Arriagada-Strodthoff P Karboune S Neufeld RJ Kermasha S 《Applied biochemistry and biotechnology》2007,142(3):263-275
The effects of selected reaction parameters, including solvent hydrophobicity, initial water activity, agitation speed, temperature
and enzyme concentration, on the biocatalytic efficiency of a chlorophyllase enzymatic extract from Phaeodactylum tricornutum in neat organic solvent media were investigated. The highest chlorophyllase specific activity of 322 nmol hydrolyzed chlorophyll
per gram of protein per minute and bioconversion yield of 91% were obtained in the reaction mixture of hexane/2-octanone (98.3:1.7,
v/v), at a controlled initial water activity of 0.90. R
O/A value, which is the ratio of the specific activity in the organic solvent to that in the aqueous/miscible organic solvent
medium, was 1.5 × 10−3. To reduce the substrate diffusional limitations, the appropriate agitation speed and enzyme concentration were determined.
The optimum temperature for maximal enzymatic activity and activation energy were 35°C and 105.0 kJ/mol, respectively. Although
the catalytic efficiency of chlorphyllase in the neat organic solvent mixture was lower than that in the aqueous medium, its
half-life time in the first environment at temperature ranging from 35 to 50°C was increased by 5.0 to 15.0 times. 相似文献
14.
J. Pablo Tomba Daniel Portinha Walter F. Schroeder Mitchell A. Winnik Willie Lau 《Colloid and polymer science》2009,287(3):367-378
This paper describes experiments that investigate the use of low glass transition temperature (T
g) latex particles consisting of oligomer to promote polymer diffusion in films formed from high molar mass polymer latex.
The chemical composition of both polymers was similar. Fluorescence resonance energy transfer (FRET) was used to follow the
rate of polymer diffusion for samples in which the high molar mass polymer was labeled with appropriate donor and acceptor
dyes. In these latex blends, the presence of the oligomer (with M
n = 24,000 g/mol, M
w/M
n = 2) was so effective at promoting the interdiffusion of the higher molar mass poly(butyl acrylate-co-methyl methacrylate; PBA/MMA = 1:1 by weight) polymer (with M
n = 43,00 g/mol, M
w/M
n = 3) that a significant amount of interdiffusion occurred during film drying. Additional polymer diffusion occurred during
film aging and annealing, and this effect could be described quantitatively in terms of free-volume theory.
This paper is dedicated to Professor Haruma Kawaguchi to honor his many contributions to the field of latex particles and
their applications. 相似文献
15.
Xu Z Li S Fu F Li G Feng X Xu H Ouyang P 《Applied biochemistry and biotechnology》2012,166(4):961-973
d-tagatose is a ketohexose that can be used as a novel functional sweetener in foods, beverages, and dietary supplements. This
study was aimed at developing a high-yielding d-tagatose production process using alginate immobilized Lactobacillus fermentum CGMCC2921 cells. For the isomerization from d-galactose into d-tagatose, the immobilized cells showed optimum temperature and pH at 65 °C and 6.5, respectively. The alginate beads exhibited
a good stability after glutaraldehyde treatment and retained 90% of the enzyme activity after eight cycles (192 h at 65 °C)
of batch conversion. The addition of borate with a molar ratio of 1.0 to d-galactose led to a significant enhancement in the d-tagatose yield. Using commercial β-galactosidase and immobilized L. fermentum cells, d-tagatose was successfully obtained from lactose after a two-step biotransformation. The relatively high conversion rate and
productivity from d-galactose to d-tagatose of 60% and 11.1 g l−1 h−1 were achieved in a packed-bed bioreactor. Moreover, lactobacilli have been approved as generally recognized as safe organisms,
which makes this L. fermentum strain an attracting substitute for recombinant Escherichia coli cells among d-tagatose production progresses. 相似文献
16.
Costa Rodrigues R Volpato G Wada K Záchia Ayub MA 《Applied biochemistry and biotechnology》2009,152(3):394-404
In this work, we describe the optimization of the ethanolysis of soybean oil by the enzyme Lipozyme™ TL-IM in the lipase-catalyzed
biodiesel synthesis and the improvement of the enzyme stability over repeated batches. The studied process variables were:
reaction temperature, substrate molar ratio, enzyme content, and volume of added water. Fractional factorial design was used
to analyze the variables so as to select those with higher influence on the reaction and then perform a central composite
design to find the optimal reaction conditions. The optimal conditions found were: temperature, 26 °C; substrate molar ratio,
7.5:1 (ethanol/oil); enzyme content, 25% in relation to oil weight; and added water, 4% in relation to oil weight. Under these
conditions, the yield conversion obtained was 69% in 12 h. The enzyme stability assessment in repeated batches was carried
out by washing the immobilized enzyme with different solvents (n-hexane, water, ethanol, and propanol) after each batch. In the treatment with n-hexane, around 80% of the enzyme activity still remains after seven cycles of synthesis, suggesting its economical application
on biodiesel production. 相似文献
17.
Laura M. Bruno José L. de Lima Filho Eduardo H. de M. Melo Heizir F. de Castro 《Applied biochemistry and biotechnology》2004,113(1-3):189-199
Mucor miehei lipase was immobilized on magnetic polysiloxane-polyvinyl alcohol particles by covalent binding with high activity recovered.
The performance of the resulting immobilized biocatalyst was evaluated in the synthesis of flavor esters using heptane as
solvent. The impact on reaction rate was determined for enzyme concentration, molar ratio of the reactants, carbon chain length
of the reactants, and alcohol structure. Ester synthesis was maximized for substrates containing excess acyl donor and lipase
loading of 25 mg/mL. The biocatalyst selectivity for the carbon chain length was found to be different concerning the organic
acids and alcohols. High reaction rates were achieved for organic acids with 8 or 10 carbons, whereas increasing the alcohol
carbon chain length from 4 to 8 carbons gave much lower esterification yields. Optimal reaction rate was determined for the
synthesis of butyl caprylate (12 carbons). Esterification performance was also dependent on the alcohol structure, with maximum
activity occurring for primary alcohol. Secondary and tertiary alcohols decreased the reaction rates by more than 40%. 相似文献
18.
Marta A. P. Langone Geraldo L. Sant'Anna Jr. 《Applied biochemistry and biotechnology》1999,79(1-3):759-770
The synthesis of tricaprylin, tricaprin, trilaurin, and trimyristin in a solvent-freesystem was conducted by mixing a commercial
immobilized lipase (Lipozyme IM 20, Novo Nordisk, Bagsvaerd, Denmark) with the organic reactants (glycerol and fatty acids)
in a 20-mL batch reactor with constant stirring. In a first set of experiments, the effect of water concentration (0–6%) on
the reaction conversion was shown to be negligible. In a second set of experiments, the effects of temperature (70–90°C),
fatty acid/glycerol molar ratio (1–5), and enzyme concentration (1–9%[w/w]) on the reaction conversion were determined by
the application of a 3×3 experimental design. The reactions were carried out for 26 h and the nonpolar phase was analyzed
by gas chromatography (GC). Appreciable levels of medium-chain triglycerides were achieved, except for tricaprylin. For the
triglyceride production, higher selectivity was attained under the following conditions: molar ratio of 5, enzyme concentration
of 5 or 9% (w/w) and temperatures of 70°C (Tricaprin), 80°C (trilaurin), and 90°C (trimyristin). Statistical analysis indicated
that the fatty acid/glycerol molar ratio was the most significant variable affecting the synthesis of triglycerides. 相似文献
19.
Phenylalanine dehydrogenase (l-PheDH) from Sporosarcina ureae was immobilized on DEAE-cellulose, modified initially with 2-amino-4,6-dichloro-s-triazine followed by hexamethylenediamine
and glutaraldehyde. The highest activity of immobilized PheDH was determined as 95.75 U/g support with 56% retained activity.
The optimum pH value of immobilized l-PheDH was shifted from pH 10.4 to 11.0. The immobilized l-PheDH showed activity variations close to the maximum value in a wider temperature range of 45–55 °C, whereas it was 40 °C
for the native enzyme. The pH and the thermal stability of the immobilized l-PheDH were also better than the native enzyme. At pH 10.4 and 25 °C, K
m values of the native and the immobilized l-PheDH were determined as K
m Phe = 0.118, 0.063 mM and K
m NAD+ = 0.234, 0.128 mM, respectively. Formed NADH at the exit of packed bed reactor column was detected by the flow-injection
analysis system. The conversion efficiency of the reactor was found to be 100% in the range of 5–600 μM Phe at 9 mM NAD+ with a total flow rate of 0.1 mL/min. The reactor was used for the analyses of 30 samples each for 3 h per day. The half-life
period of the reactor was 15 days. 相似文献
20.
Karra-Châabouni M Bouaziz I Boufi S Botelho do Rego AM Gargouri Y 《Colloids and surfaces. B, Biointerfaces》2008,66(2):168-177
Rhizopus oryzae lipase (ROL) was immobilized by adsorption onto oxidized cellulose fibers and regenerated films. The maximum adsorption level increases with the raise in the amount of carboxylic groups on cellulose surface confirming that adsorption is being governed mainly by electrostatic interaction between the enzyme and the substrate. This hypothesis was further confirmed by zeta-potential measurements showing a decrease in the zeta-potential of the fibers after enzyme adsorption. XPS analysis showed an intensification of the N 1s peak attesting the presence of the enzyme on the surface. The effect of temperature, pH and solvent polarity on the immobilized enzyme activity and stability was investigated. The catalytic esterification of oleic acid with n-butanol has been carried on using hexane as an organic solvent. A high conversion yield was obtained (about 80%) at 37 degrees C with a molar ratio of oleic acid to butanol 1:1 and 150IU immobilized lipase. The adsorption achieved two successive cycles with the same efficiency, and started to lose its activity during the third cycle. 相似文献