共查询到20条相似文献,搜索用时 31 毫秒
1.
Summary A lipase from Candida rugosa immobilized on styrene-divinylbenzene copolymer was used to catalyse the direct esterification of butanol and butyric acid. A factorial design was employed to evaluate the effects of temperature (37–50 °C), substrate molar ratio of butyric acid to butanol (0.6 to 2.0) and enzyme amount (0.2–0.4 g) on the ester yield. The main effects were fitted by multiple regression analysis to a linear model and maximum ester yield could be obtained working at 41 °C with 0.4 g of lipase. The mathematical model obtained, representing the ester yield has been found to describe adequately the experimental results. Under optimal conditions, concentration of 32.4 g butyl butyrate/l that corresponds to a yield of 75% was obtained. 相似文献
2.
Xiao-Wei Yu Yong-Quan Li Shi-Miao Zhou Yu-Yi Zheng 《World journal of microbiology & biotechnology》2007,23(8):1091-1098
Aspergillus niger with mycelium-bound tannase activity was employed to investigate the synthesis of propyl gallate from gallic acid and 1-propanol
in organic solvents. The effects of various organic solvents (log P: −1.0 to 6.6) on the enzymatic reactions showed that benzene (log P: 2.0) was the most suitable solvent. The water content and protonation state of mycelium-bound enzyme both had significant
effects on the activity of tannase. The maximum molar conversion (65%) was achieved with 7.3% (v/v) 1-propanol and 5.56 mM
gallic acid at stirring speeds of 200 rev/min, 40 °C in presence of anhydrous sodium sulfate and PEG-10,000. Enzyme specificity
for the alcohol portion (C1–C8) of the ester showed that the optimum synthesis was observed with alcohols ranging from C3 to C5. 相似文献
3.
Naz Chaibakhsh Mohd Basyaruddin Abdul Rahman Suraini Abd-Aziz Mahiran Basri Abu Bakar Salleh Raja Noor Zaliha Raja Abdul Rahman 《Journal of industrial microbiology & biotechnology》2009,36(9):1149-1155
Immobilized Candida antarctica lipase-catalyzed esterification of adipic acid and oleyl alcohol was investigated in a solvent-free system (SFS). Optimum
conditions for adipate ester synthesis in a stirred-tank reactor were determined by the response surface methodology (RSM)
approach with respect to important reaction parameters including time, temperature, agitation speed, and amount of enzyme.
A high conversion yield was achieved using low enzyme amounts of 2.5% w/w at 60°C, reaction time of 438 min, and agitation
speed of 500 rpm. The good correlation between predicted value (96.0%) and actual value (95.5%) implies that the model derived
from RSM allows better understanding of the effect of important reaction parameters on the lipase-catalyzed synthesis of adipate
ester in an organic solvent-free system. Higher volumetric productivity compared to a solvent-based system was also offered
by SFS. The results demonstrate that the solvent-free system is efficient for enzymatic synthesis of adipate ester. 相似文献
4.
Regioselective undecylenoylation of purine nucleosides as potential dual prodrugs was achieved by Candida antarctica lipase B using adenosine as a model reactant. The optimum organic solvent, molar ratio of vinyl ester to nucleoside, enzyme
dosage, reaction temperature and molecular sieve amount were anhydrous THF, 5:1, 20 U/ml, 45°C and 75 mg/ml, respectively.
Under the optimum conditions, the initial reaction rate, yield and 5′-regioselectivity were 1.1 mM/h, 90% and >99%, respectively.
The enzymatic acylation of various nucleosides furnished the desired 5′-ester derivatives with the yields of 60–95% and 5′-regioselectivities
of >99%. In addition, the lipase displayed excellent operational stability in THF, and retained 96% of its initial activity
after reused for five batches. 相似文献
5.
Aline Richetti Selma G. F. Leite Octávio A. C. Antunes Lindomar A. Lerin Rogério M. Dallago Daniel Emmerich Marco Di Luccio J. Vladimir Oliveira Helen Treichel Débora de Oliveira 《Bioprocess and biosystems engineering》2010,33(3):331-337
This work reports the optimization of 2-ethylhexyl palmitate production by esterification reaction in a solvent-free system
using a commercial lipase as catalyst. For this, a sequential strategy was performed applying three experimental designs.
An empirical model was built so as to assess the effects of process variables on the reaction conversion. Afterward, the operating
conditions that optimized 2-ethylhexyl palmitate production were determined to be acid to alcohol molar ratio of 1:5.5, 70 °C,
150 rpm and 10.5 wt% of enzyme, leading to a reaction conversion as high as 93%. From this point, a kinetic study was carried
out evaluating the influence of acid to alcohol molar ratio, enzyme concentration and temperature on product yield. Results
obtained in this step allow to conclude that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme
concentration (10 wt%) and temperature of 70 °C led to nearly complete reaction conversion. 相似文献
6.
《Biocatalysis and Biotransformation》2013,31(5-6):303-308
Immobilized Candida antarctica lipase B, Novozym® 435, was used in the esterification of adipic acid and alcohols with different chain lengths (C1–C18). Optimum conditions for the synthesis of adipate esters were obtained using response surface methodology (RSM) with respect to important reaction parameters including time, temperature, substrate molar ratio and amount of enzyme. Alcohol chain length specificity of the enzyme in the synthesis of adipate esters was also determined. Minimum reaction time (215 min) for achieving maximum ester yield was obtained for butyl alcohol. Methanol required an increased time (358 min) and enzyme amount (10.2%, w/w) for attaining maximum yield. The maximum required temperature and time of 65°C and 523 min, respectively, were obtained for the synthesis of dioctadecyl adipate. The results demonstrate that alcohol chain length is a determining parameter in optimization of the lipase-catalyzed synthesis of adipate esters. Reactions under optimized conditions yielded a high percentage of esterification (>97%). The optimum conditions can be used to scale up the process. 相似文献
7.
Alankar Vaidya Gayatri Gera Sonti Ramakrishna 《World journal of microbiology & biotechnology》2008,24(12):2987-2995
Commercial available lipases viz. Lipozyme™, Novozyme-735 and Candida antartica lipase-B (CAL-B) were immobilized on seven different supports by simple adsorption process. The importance of suitable enzyme–support
combination in esterification of lauric acid and iso-propanol was validated experimentally. Effect of long chain fatty acids
(C4–C18) and small chain monohydric alcohols (C1–C6) on specific activities of different immobilized lipases were evaluated.
Lauric acid (C12) was found to be the most preferred fatty acid and t-amyl alcohol (C5) being the best alcohol. CAL-B adsorbed on Lewatit was the most efficient immobilized enzyme for esterification
reaction. Selectivity constant for lauric acid (3.4) was the highest among all fatty acids tested, whereas there was not much
difference in selectivity between different alcohols. Furthermore, increase in fatty acid unsaturation leads to decrease catalytic
efficiency of immobilized CAL-B. The optimum conditions for t-amyllaurate synthesis were as follows: lauric acid—0.5 M, t-amyl
alcohol—0.3 M and amount of immobilized enzyme—150 mg. Finally, CAL-B adsorbed on Lewatit was reused for three consecutive
cycles. 相似文献
8.
Lipase-catalyzed caffeic acid phenethyl ester (CAPE) synthesis in ionic liquid, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][Tf2N]), was investigated in this study. The effects of several reaction conditions, including reaction time, reaction temperature, substrate molar ratio of phenethyl alcohol to caffeic acid (CA), and weight ratio of enzyme to CA, on CAPE yield were examined. In a single parameter study, the highest CAPE yield in [Emim][Tf2N] was obtained at 70 °C with a substrate molar ratio of 30:1 and weight ratio of enzyme to CA of 15:1. Based on these results, response surface methodology (RSM) with a 3-level-4-factor central composite rotatable design (CCRD) was adopted to evaluate enzymatic synthesis of CAPE in [Emim][Tf2N]. The four major factors were reaction time (36–60 h), reaction temperature (65–75 °C), substrate molar ratio of phenethyl alcohol to CA (20:1–40:1), and weight ratio of enzyme to CA (10:1–20:1). A quadratic equation model was used to analyze the experimental data at a 95 % confidence level (p < 0.05). A maximum conversion yield of 99.8 % was obtained under the optimized reaction conditions [60 h, 73.7 °C, substrate molar ratio of phenethyl alcohol to CA (27.1:1), and weight ratio of enzyme to CA (17.8:1)] established by our statistical method, whereas the experimental conversion yield was 96.6 ± 2 %. 相似文献
9.
《Biocatalysis and Biotransformation》2013,31(3):192-200
AbstractImmobilized Candida antarctica lipase, Novozym 435, was used to catalyze the esterification reaction between betulinic acid and phthalic anhydride to synthesize 3-O-phthalyl betulinic acid in n-hexane/chloroform. Response surface methodology based on a five-level, four-variable central composite rotatable design was employed to evaluate the effects of synthesis parameters such as reaction time, reaction temperature, enzyme amount and substrate molar ratio on the yield of ester. Based on the response surface model, the optimal enzymatic synthesis conditions were predicted to be: reaction time 20.3 h, reaction temperature 53.9°C, enzyme amount 145.6 mg, betulinic acid to phthalic anhydride molar ratio 1:1.11. The predicted yield was 65.8% and the actual yield was 64.7%. 相似文献
10.
S.-W. Chang C.-J. Yang F.-Y. Chen C.C. Akoh C.-J. Shieh 《Journal of Molecular Catalysis .B, Enzymatic》2009,56(1):7-12
l-Ascorbyl laurate is a fatty acid derivative of l-ascorbic acid which can be widely used as a natural antioxidant in both lipid containing food and cosmetic applications. To avoid any possible harmful effects from chemically synthesized product, the enzymatic synthesis appears to be the best way to satisfy the consumer demand for natural antioxidants. The ability of immobilized lipase from Candida antarctica (Novozym® 435) to catalyze the direct esterification between l-ascorbic acid and lauric acid was investigated. Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time (2–10 h), temperature (25–65 °C), enzyme amount (10–50% w/w of l-ascorbic acid), and substrate molar ratio of l-ascorbic acid to lauric acid (1:1–1:5) on percentage molar conversion to l-ascorbyl laurate. Based on the analysis result of ridge max, the optimal enzymatic synthesis conditions were predicted as follows: reaction time 6.7 h, temperature 30.6 °C, enzyme amount 34.5%, substrate molar ratio 1:4.3; and the optimal actual yield was 93.2%. 相似文献
11.
Natália Paroul Adriana Biasi Ane Cheila Rovani Camile Prigol Rogerio Dallago Helen Treichel Rogério L. Cansian J. Vladimir Oliveira Débora de Oliveira 《Bioprocess and biosystems engineering》2010,33(5):583-589
This work investigated the influence of temperature, enzyme concentration, substrates molar ratio, in the absence and presence
of organic solvent, at two molar ratios of the substrates on the enzymatic production of linalil esters using the immobilized
lipase Novozym 435 as catalyst, different acids and linalool and Ho-Sho essential oil as substrates. The best reaction conversion
was obtained at the highest temperature (70 °C), for both solvent free (3.81%) and with solvent addition (2.25%), for a solvent
to substrates molar ratio of 2:1, enzyme concentration of 5 wt% and acid to alcohol molar ratio of 1:1. The reaction kinetics
revealed that Ho-Sho essential oil afforded the greatest conversions when compared with pure linalool. Higher linalil esters
production were achieved after 10 h reaction (5.58%) in 2:1 solvent to substrates molar ratio, with enzyme concentration of
5 wt%, at 70 °C and anhydride to alcohol molar ratio of 1:1 using Ho-Sho essential oil as substrate. 相似文献
12.
《Journal of Molecular Catalysis .B, Enzymatic》2011,70(3-4):107-111
A mild and efficient method for the conversion of fatty acid methyl esters from lard into ascorbyl esters via lipase-catalyzed transesterification in co-solvent mixture is described. A solvent engineering strategy was firstly applied to improve fatty acid ascorbyl esters production. The co-solvent mixture of 30% t-pentanol:70% isooctane (v/v) was optimal. Response surface methodology (RSM) and central composite design (CCD) were employed to estimate the effects of reaction parameters, such as reaction time (12–36 h), temperature (45–65 °C), enzyme amount (10–20%, w/w, of fat acid methyl esters), and substrate molar ratio of fatty acid methyl esters to ascorbic acid (8:1–12:1) for the synthesis of fatty acid ascorbyl esters in co-solvent mixture. Based on the RSM analysis, the optimal reaction conditions were determined as follows: reaction time 34.32 h, temperature 54.6 °C, enzyme amount 12.5%, substrate molar ratio 10.22:1 and the maximum conversion of fatty acid ascorbyl esters was 69.18%. The method proved to be applicable for the synthesis of ascorbyl esters using Novozym 435 in solvent. 相似文献
13.
《Journal of Molecular Catalysis .B, Enzymatic》2011,73(3-4):150-156
Short chain alkyl esters are well appreciated for fruity flavors they provide. These are mainly applied to the fruit-flavored products like jam, jelly, beverages, wine and dairy. Cutinase from Burkholderia cepacia NRRL B 2320 was found to be active in catalyzing the synthesis of alkyl esters in organic solvent. The optimal temperature range for the enzyme catalyzed synthesis was found to be from 35 °C to 40 °C. The maximum conversion (%) during synthesis of ester was obtained for butyric acid (C4) and valeric acid (C5) with butanol reflecting the specificity of the enzyme for short-chain length fatty acids. In case of alcohol specificity, butanol was found to be most preferred substrate by the enzyme and conversion (%) decreased with increasing carbon chain length of alcohol used in the esterification reaction. The kinetic analysis for the synthesis of butyl butyrate by varying concentration of one substrate at a time (butanol or butyric acid), showed that Ping–Pong Bi Bi model with acid inhibition and influence of initial water is most suitable model for the prediction of the reaction kinetics. 相似文献
14.
Paroul N Grzegozeski LP Chiaradia V Treichel H Cansian RL Oliveira JV de Oliveira D 《Bioprocess and biosystems engineering》2011,34(3):323-329
This study reports the maximization of geranyl oleate production by esterification of geraniol and oleic acid in a solvent-free
system using a commercial lipase as catalyst. The operating conditions that maximized geranyl oleate production were determined
to be 40 °C, geraniol to oleic acid molar ratio of 5:1, 150 rpm and 10 wt% of enzyme, with a resulting reaction conversion
of about 93%. After determining the best reaction parameters, a kinetic study was performed and the results obtained in this
step allow to conclude that an excess of alcohol (alcohol to acid molar ratio of 5:1), relatively low enzyme concentration
(5 wt%) and temperature of 50 °C afforded nearly complete reaction conversion after 1 h of reaction. New experimental data
on enzymatic esterification of geraniol and oleic acid for geranyl oleate production are reported in this work, showing a
promising perspective of the technique to overcome the inconvenience of the chemical-catalyzed route. 相似文献
15.
Identification and characterization of fermentation inhibitors formed during hydrothermal treatment and following SSF of wheat straw 总被引:1,自引:0,他引:1
Mette Hedegaard Thomsen Anders Thygesen Anne Belinda Thomsen 《Applied microbiology and biotechnology》2009,83(3):447-455
A pilot plant for hydrothermal treatment of wheat straw was compared in reactor systems of two steps (first, 80°C; second,
190–205°C) and of three steps (first, 80°C; second, 170–180°C; third, 195°C). Fermentation (SSF) with Sacharomyces cerevisiae of the pretreated fibers and hydrolysate from the two-step system gave higher ethanol yield (64–75%) than that obtained from
the three-step system (61–65%), due to higher enzymatic cellulose convertibility. At the optimal conditions (two steps, 195°C
for 6 min), 69% of available C6-sugar could be fermented into ethanol with a high hemicellulose recovery (65%). The concentration
of furfural obtained during the pretreatment process increased versus temperature from 50 mg/l at 190°C to 1,200 mg/l at 205°C
as a result of xylose degradation. S. cerevisiae detoxified the hydrolysates by degradation of several toxic compounds such as 90–99% furfural and 80–100% phenolic aldehydes,
which extended the lag phase to 5 h. Acetic acid concentration increased by 0.2–1 g/l during enzymatic hydrolysis and 0–3.4 g/l
during fermentation due to hydrolysis of acetyl groups and minor xylose degradation. Formic acid concentration increased by
0.5–1.5 g/l probably due to degradation of furfural. Phenolic aldehydes were oxidized to the corresponding acids during fermentation
reducing the inhibition level. 相似文献
16.
Optimized synthesis of (Z)-3-hexen-1-yl caproate using germinated rapeseed lipase in organic solvent
Muhammad Liaquat 《Journal of Molecular Catalysis .B, Enzymatic》2011,68(1):59-65
(Z)-3-hexen-1-yl esters are important green top-note components of food flavors and fragrances. Effects of various process conditions on (Z)-3-hexen-1-yl caproate synthesis employing germinated rapeseed lipase acetone powder in organic solvent were investigated. Rapeseed lipase catalyzed ester formation more efficiently with non-polar compared to polar solvents despite high enzyme stability in both types of solvents. Maximum ester yield (90%) was obtained when 0.125 M (Z)-3-hexen-1-ol and caproic acid were reacted at 25 °C for 48 h in the presence of 50 g/L enzyme in heptane. Enzyme showed little sensitivity towards aw with optimum yield at 0.45, while added water did not affect ester yield. Esterification reduced by increasing molecular sieves (>0.0125%, w/v). The highest yields of caproic acid were obtained with isoamyl alcohol (93%) followed by butanol and (Z)-3-hexen-1-o1 (88%) respectively reflecting the enzyme specificity for straight and branched chain alcohols. Secondary alcohols showed low reactivity, while tertiary alcohol had either very low reactivity or not esterified at all. A good relationship has been found between ester synthesis and the solvent polarity (log P value); while no correlation for the effect of solvents on residual enzyme activity was observed. It may be concluded that germinated rapeseed lipase is a promising biocatalyst for the synthesis of valuable green flavor note compound. The enzyme also showed a wide range of temperature stability (5–50 °C). 相似文献
17.
In this study, benzyl benzoate was successfully synthesized via enzymatic acylation using three immobilized enzymes as biocatalysts. Different acyl donors (benzoic acid and benzoic anhydride), operation regimes (batch, fed-batch), mixing modes (conventional mechanical stirring and ultrasound), process parameters (temperature, substrate molar ratio of acyl donor to acyl acceptor), presence or absence of solvents, enzyme amount and type were evaluated. Benzoic acid is a solid that is difficult to solubilize and, thus, was not efficient as acyl donor for the synthesis of benzyl benzoate. On the other hand, benzoic anhydride was very effective for the acylation of benzyl benzoate, and the presence of an excess of benzyl alcohol was essential to ensure the solute-solvent intermolecular attractions and good substrate solubilization, allowing the ester synthesis to be performed in the absence of organic solvents. The ultrasound was effective in increasing increase the initial reaction rate and the final conversion (88 %). However, the Lipozyme TL-IM and RM-IM supports were damaged, and the reuse was unfeasible. The batch and fed-batch approaches in conventional stirring ensured high conversions of 92 and 90 %, respectively, for batch (anhydride: alcohol 1:6) and fed-batch (1:3) using the Lipozyme TL-IM as biocatalyst. The controlled addition of the anhydride (fed-batch) allowed the reduction of alcohol molar ratio but decreased the reaction rates, and the maximum conversions were reached only after 24 h, while the batch approach had 92 % of conversion after 6 h. The yield of benzyl benzoate was high at 6 wt.% of enzyme, low temperature (50 °C), and simple reactor operation (batch). Results show the feasibility of the synthesis of benzyl benzoate via acylation using a green process that may be an alternative route to the chemical synthesis. 相似文献
18.
《Process Biochemistry》2007,42(9):1362-1366
Hexyl laurate, a medium-chain ester carried about fruity flavor, is primarily used in personal care formulations as an important emollient for cosmetic applications. On the basis of the hexyl laurate could be successfully synthesized by lipase within a batch system in our previous report. This study aimed to develop an optimal continuous procedure of lipase-catalyzed hexyl laurate synthesis in a packed-bed bioreactor to investigate the possibility of large-scale production further. The ability of lipase from Rhizomucor miehei (Lipozyme IM-77) to catalyze the direct-esterification of 1-hexanol and lauric acid in n-hexane was investigated. Response surface methodology (RSM) and 3-level-3-factor fractional factorial design were employed to evaluate the effects of synthesis parameters, such as reaction temperature (35–55 °C), mixture flow rate (1.5–4.5 mL/min) and substrate molar ratio 1-hexanol to lauric acid (1:1–1:3) on production rate (μmol/min) of hexyl laurate by direct-esterification. Based on the analysis of ridge max, the optimum synthesis conditions for hexyl laurate were as follows: 45 °C of reaction temperature, substrate molar ratio 1:2 and reaction flow rate 4.5 mL/min. The optimum predicted production rate was 435.6 ± 0.9 μmol/min and the actual value was 437.6 ± 0.4 μmol/min. 相似文献
19.
Purification and functional characterization of endo-β-mannanase MAN5 and its application in oligosaccharide production from konjac flour 总被引:1,自引:0,他引:1
Min Zhang Xiu-Lan Chen Zhi-Hua Zhang Cai-Yun Sun Lei-Lei Chen Hai-Lun He Bai-Cheng Zhou Yu-Zhong Zhang 《Applied microbiology and biotechnology》2009,83(5):865-873
MAN5, the main extracellular saccharide hydrolase from Bacillus sp. MSJ-5, is an endo-β-mannanase with a demand of at least five sugar moieties for effective cleavage. It has a pH optimum
of 5.5 and a temperature optimum of 50°C and is stable at pH 5–9 or below 65°C. MAN5 has a very high ability to hydrolyze
konjac flour, 10 U/mg of which could completely liquefy konjac flour gum in 10 min at 50°C. HPLC analysis showed that most
glucomannan in the konjac flour was hydrolyzed into a large amount of oligosaccharides with DP of 2–6 and a very small amount
of monosaccharide. With the culture supernatant as enzyme source, the optimum condition to prepare oligosaccharides from konjac
flour was obtained as 10 mg/ml konjac flour incubated with 10 U/mg enzyme at 50°C for 24 h. With this condition, more than
90% polysaccharides in the konjac flour solution were hydrolyzed into oligosaccharides and a little monosaccharide (2.98%
of the oligosaccharides). Konjac flour is an underutilized agricultural material with low commercial value in China. With
MAN5, konjac flour can be utilized to generate high value-added oligosaccharides. The high effectiveness and cheapness of
this technique indicates its potential in industry.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Min Zhang and Xiu-Lan Chen contributed equally to this work. 相似文献
20.
Soria F Ellenrieder G Oliveira GB Cabrera M Carvalho LB 《Applied microbiology and biotechnology》2012,93(3):1127-1134
α-l-Rhamnosidase from Aspergillus terreus was covalently immobilized on the following ferromagnetic supports: polyethylene terephthalate (Dacron-hydrazide), polysiloxane/polyvinyl
alcohol (POS/PVA), and chitosan. The powdered supports were magnetized by thermal coprecipitation method using ferric and
ferrous chlorides, and the immobilization was carried out via glutaraldehyde. The activity of the Dacron-hydrazide (0.53 nkat/μg
of protein) and POS/PVA (0.59 nkat/μg of protein) immobilized enzyme was significantly higher than that found for the chitosan
derivative (0.06 nkat/μg of protein). The activity–pH and activity–temperature profiles for all immobilized enzymes did not
show difference compared to the free enzyme, except the chitosan derivative that presented higher maximum temperature at 65 °C.
The Dacron-hydrazide derivative thermal stability showed a similar behavior of the free enzyme in the temperature range of
40–70 °C. The POS/PVA and chitosan derivatives were stable up to 60 °C, but were completely inactivated at 70 °C. The activity
of the preparations did not appreciably decrease after ten successive reuses. Apparent K
m of α-l-rhamnosidase immobilized on magnetized Dacron-hydrazide (1.05 ± 0.22 mM), POS/PVA (0.57 ± 0.09 mM), and chitosan (1.78 ± 0.24 mM)
were higher than that estimated for the soluble enzyme (0.30 ± 0.03 mM). The Dacron-hydrazide enzyme derivative showed better
performance than the free enzyme to hydrolyze 0.3% narigin (91% and 73% after 1 h, respectively) and synthesize rhamnosides
(0.116 and 0.014 mg narirutin after 1 h, respectively). 相似文献