Enzymatic synthesis of isopropyl myristate using immobilized lipase from Bacillus cereus MTCC 8372

A purified alkaline thermo-tolerant bacterial lipase from Bacillus cereus MTCC 8372 was immobilized on a Poly (MAc-co-DMA-cl-MBAm) hydrogel. The hydrogel showed approximately 94% binding capacity for lipase. The immobilized lipase (2.36 IU) was used to achieve esterification ofmyristic acid and isopropanol in n-heptane at 65 degrees C under continuous shaking. The myristic acid and isopropanol when used at a concentration of 100 mM each in n-heptane resulted in formation of isopropyl myristate (66.0 +/- 0.3 mM) in 15 h. The reaction temperature below or higher than 65 degrees C markedly reduced the formation of isopropyl myristate. Addition of a molecular sieve (3 A x 1.5 mm) to the reaction mixture drastically reduced the ester formation. The hydrogel bound lipase when repetitively used to perform esterification under optimized conditions resulted in 38.0 +/- 0.2 mM isopropyl myristate after the 3rd cycle of esterification.     

Effect of Solvents and Kinetic Parameters on Synthesis of Ethyl Propionate Catalysed by Poly (AAc-co-HPMA-cl-MBAm)-Matrix-Immobilized Lipase of Pseudomonas aeruginosa BTS-2.

Summary A purified alkaline thermo-tolerant bacterial lipase from Pseudomonas aeruginosa BTS-2 was immobilized on a poly (AAc-co-HPMA-cl-MBAm) hydrogel network. The hydrogel showed approximately 95% binding efficiency for lipase (specific activity 1.96 U mg⁻¹). The immobilized enzyme achieved 65.1% conversion of ethanol and propionic acid (100 mM each) into ethyl propionate in n-nonane at 65 °C in 9 h. When alkane of C-chain length lower than n-nonane was used as the organic solvent, the conversion of ethanol and propionic acid into ethyl propionate decreased with a decrease in the log P value of alkanes. The immobilized lipase retained approximately 30% of its original catalytic activity after five cycles of reuse for esterification of ethanol and propionic acid into ethyl propionate at temperature 65 °C in 3 h. Addition of a molecular sieve (3 ?) to the reaction mixture enhanced the formation of ethyl propionate to 89.3%. Moreover, ethanol and propionic acid when taken a molar ratio of 3:1 further promoted the conversion rate to 94%. However, an increase in the molar ratio of propionic acid with respect to ethanol resulted in a decline of ethyl propionate synthesis.     

Synthesis of ethyl ferulate in organic medium using celite-immobilized lipase

In the present work we have evaluated synthesis of ethyl ferulate by the esterification reaction of ferulic acid and ethanol catalyzed by a commercial lipase (Steapsin) immobilized onto celite-545 in a short period of 6 h in DMSO. The immobilized lipase was treated with cross-linking agent glutaraldehyde (1%; v/v). The optimum synthesis of ethyl ferulate was recorded at 45 °C, pH 8.5 and 1:1 ratio of ethanol and ferulic acid. Co²⁺, Ba²⁺and Pb²⁺ ions enhanced the synthesis of ethyl ferulate Hg²⁺, Cd³⁺and NH⁴⁺ ions had mild inhibitory effect. The celite-bound lipase produced 68 mM of ethyl ferulate under optimized reaction conditions.     

Evaluation of immobilized lipases on poly-hydroxybutyrate beads to catalyze biodiesel synthesis

Five microbial lipase preparations from several sources were immobilized by hydrophobic adsorption on small or large poly-hydroxybutyrate (PHB) beads and the effect of the support particle size on the biocatalyst activity was assessed in the hydrolysis of olive oil, esterification of butyric acid with butanol and transesterification of babassu oil (Orbignya sp.) with ethanol. The catalytic activity of the immobilized lipases in both olive oil hydrolysis and biodiesel synthesis was influenced by the particle size of PHB and lipase source. In the esterification reaction such influence was not observed. Geobacillus thermocatenulatus lipase (BTL2) was considered to be inadequate to catalyze biodiesel synthesis, but displayed high esterification activity. Butyl butyrate synthesis catalyzed by BTL2 immobilized on small PHB beads gave the highest yield (≈90 mmol L(-1)). In biodiesel synthesis, the catalytic activity of the immobilized lipases was significantly increased in comparison to the free lipases. Full conversion of babassu oil into ethyl esters was achieved at 72 h in the presence of Pseudozyma antarctica type B (CALB), Thermomyces lanuginosus lipase (Lipex(?) 100 L) immobilized on either small or large PHB beads and Pseudomonas fluorescens (PFL) immobilized on large PHB beads. The latter preparation presented the highest productivity (40.9 mg of ethyl esters mg(-1) immobilized protein h(-1)).     

Purification of a moderate thermotolerant Bacillus coagulans BTS1 lipase and its properties in a hydro-gel system

An alkaline thermotolerant lipase of Bacillus coagulans BTS1 was successively purified by ammonium sulfate precipitation and DEAE anion exchange chromatography. The purified lipase immobilized in alginate beads showed an optimal activity at pH 7.5 and 55 degrees C. A pH of 5.0 or 10.0 completely quenched the activity of immobilized lipase. The alginate-bound lipase retained its activity following exposure to most of the organic solvents including amines, alkanes and alcohols. Chloride salt of Al3+, Co2+, Mg2+ and NH4+ modulated the lipase activity of alginate-immobilized enzyme. The alginate entrapped lipase showed a preferentially high activity towards p-nitrophenyl palmitate (C: 16) and activity of matrix increased following exposure to SDS. Moreover, the immobilized lipase retained more than 50% of its activity after 3rd cycle of reuse.     

Purification and properties of a novel extra-cellular thermotolerant metallolipase of Bacillus coagulans MTCC-6375 isolate

A novel extra-cellular lipase from Bacillus coagulans MTCC-6375 was purified 76.4-fold by DEAE anion exchange and Octyl Sepharose chromatography. The purified enzyme was found to be electrophoretically pure by denaturing gel electrophoresis and possessed a molecular mass of approximately 103 kDa. The lipase was optimally active at 45 degrees C and retained approximately 50% of its original activity after 20 min of incubation at 55 degrees C. The enzyme was optimally active at pH 8.5. Mg2+, Cu2+, Ca2+, Hg2+, Al3+, and Fe3+ at 1mM enhanced hydrolytic activity of the lipase. Interestingly, Hg2+ ions resulted in a maximal increase in lipase activity but Zn2+ and Co2+ ions showed an antagonistic effect on this enzyme. EDTA at 150 mM concentration inhibited the activity of lipase but Hg2+ or Al3+ (10mM) restored most of the activity of EDTA-quenched lipase. Phenyl methyl sulfonyl fluoride (PMSF, 15 mM) decreased 98% of original activity of lipase. The lipase was more specific to p-nitrophenyl esters of 8 (pNPC) and 16 (pNPP) carbon chain length esters. The lipase had a Vmax and Km of 0.44 mmol mg(-1)min(-1) and 28 mM for hydrolysis of pNPP, and 0.7 mmol mg(-1)min(-1) and 32 mM for hydrolysis of pNPC, respectively.     

Ethyl oleate synthesis using Candida rugosa lipase in a solvent-free system. Role of hydrophobic interactions

The solvent-free esterification reaction of a commercial oleic acid and ethanol was selected as the test reaction for Candida rugosa lipase immobilized on polypropylene (PP) at 318 K (initial molar ratio 1:1). Adding of water from 0 to 30 wt. % (in gram per gram of fatty acid x 100) and the pretreatment of Candida rugosa lipase with polyethylenglycol (PEG), octane, and acetone increases the conversion to ethyl esters. The role of hydrophobic interactions of the lipase with PP and PEG was studied using molecular mechanics (MM2) for calculation of steric energies and the parametrized model (PM3) for calculation of enthalpy changes upon interaction. The nonpolar lateral groups of amino acids interact strongly with PP, whereas polar groups interact more strongly with PEG. Both interactions stabilize the open, active conformation of the lipase from Candida rugosa. Activities ranged from 5 x 10(-5) to 2.0 x 10(-4) mol ethyl oleate/h/mg enzyme, depending on reaction conditions. Steric energy changes vary between +30 and -10 kcal/mol, whereas the enthalpy changes ranged from +10 to -10 kcal/mol.     

Purification and properties of Amycolatopsis mediterranei DSM 43304 lipase and its potential in flavour ester synthesis

An extracellular thermostable lipase from Amycolatopsis mediterranei DSM 43304 has been purified to homogeneity using ammonium sulphate precipitation followed by anion exchange chromatography and hydrophobic interaction chromatography. This protocol resulted in a 398-fold purification with 36% final recovery. The purified A. mediterranei DSM 43304 lipase (AML) has an apparent molecular mass of 33 kDa. The N-terminal sequence, AANPYERGPDPTTASIEATR, showed highest similarity to a lipase from Streptomyces exfoliatus. The values of K(m)(app) and V(max)(app) for p-nitrophenyl palmitate (p-NPP) at the optimal temperature (60°C) and pH (8.0) were 0.099±0.010 mM and 2.53±0.06 mmol/min mg, respectively. The purified AML displayed significant activity towards a range of short and long chain triglyceride substrates and p-nitrophenyl esters. Hydrolysis of glycerol ester bonds occurred non-specifically. The purified AML displayed significant stability in the presence of organic solvents (40%, v/v) and catalyzed the synthesis of the flavour ester isoamyl acetate in free and immobilized states.     

Recombinant Candida rugosa lipase 2 from Pichia pastoris: immobilization and use as biocatalyst in a stereoselective reaction

The characterization of the recombinant Candida rugosa Lip2 (r-Lip2) isoenzyme obtained from fed-batch cultures of Pichia pastoris under PAOX promoter was carried out, determining the optimal pH and temperature as well as their catalytic performance in both hydrolysis and synthesis reactions comparing with purified native Lip2 (n-Lip2) previously determined. The substrate specificity of r-Lip2 in hydrolysis reactions was determined with a series of triacylglycerols and p-nitrophenyl esters of variable acyl chain length. r-Lip2 showed the maximum specificity for both substrates towards medium-chain esters (C-8), similar behavior was observed with n-Lip2. However, significant differences were observed towards unsaturated substrates (triolein) or short-chain esters. A statistical design applied to study the effect of pH and temperature on lipase stability shown that r-Lip2, like n-Lip2, was more sensitive to pH than temperature changes. Nevertheless, the overall stability of soluble r-Lip2 was lower than soluble n-Lip2. The stability of r-lip2 was significantly improved by immobilization onto EP100, an excellent support for lipases with yields around 95% for offered lipolytic activity lower than 600 AU/mL. Finally, immobilized r-Lip2 was tested in the resolution of ibuprofen in isooctane by means of enantioselective esterification using 1-butanol as esterifying agent. r-Lip2 showed a better performance in terms of enantiomeric excess (74%) and enatiomeric factor (96%) than n-Lip2 (56 and 80%, respectively) for the same conversion (40%). Thus, r-Lip2 should be considered a good and pure biocatalyst, easy to produce and with a remaining activity of ca. 90% after one reaction cycle when immobilized on EP100.     

Cloning, expression and characterization of a lipase gene from the Candida antarctica ZJB09193 and its application in biosynthesis of vitamin A esters

Lipase is one of the most important industrial enzymes, which has been widely used in the preparation of food additives, cosmetics and pharmaceuticals industries. In order to obtain a large amount of lipase, the lipase gene from Candida antarctica ZJB09193 was cloned, and expressed in Pichia pastoris with the vector pPICZαA. Under the optimal conditions, the yield of recombinant lipase in the culture broth reached 3.0 g/L. After purification, the properties of recombinant lipase were studied: the optimum pH and temperature were pH 8.0 and 52°C, Ca(2+) activated the activity of lipase, and the apparent K(m) and V(max) values for p-nitrophenyl acetate were 0.34 mM and 7.36 μmol min(-1) mg(-1), respectively. Furthermore, the recombinant lipase was immobilized on pretreated textile for biosynthesis of vitamin A esters. In a system of n-hexane, 0.3 g immobilized recombinant lipase was used in the presence of 0.06 g vitamin A acetate and 0.55 mmol fatty acid (nine different fatty acids were tested). The yield of all vitamin A esters exceeded 78% in 7h at 30°C except using lactic acid and hexanoic acid as substrates. After optimization, the yield of vitamin A palmitate reached 87%. This study has the potential to be developed into industrial application.     

Purification and characterization of an alkaline lipase from a newly isolated Acinetobacter radioresistens CMC-1

A novel alkaline lipase showing a broad range of specificity towards long chain triacylglycerols or p-nitrophenyl esters was purified to homogeneity from Acinetobacter radioresistens CMC-1. Its molecular mass was 45 kDa (by SDS-PAGE), pI of approx. 5.2, and optimally activity at 10.5 and 40°C. Using triolein as substrate, the lipase showed 1,3-positional specificity for hydrolyzing ester bonds. The enzyme was activated in 40% (v/v) dimethylsulfoxide and 20% (v/v) dimethylformamide. © Rapid Science Ltd. 1998     

A two steps enzymatic procedure to obtain sterol esters,tocopherols and fatty acid ethyl esters from soybean oil deodorizer distillate

Soybean oil deodorizer distillate (SODD) was enzymatically modified to obtain a product mixture comprised mainly of sterol esters, tocopherols, and fatty acid ethyl esters. Firstly, the original SODD was mixed with oleic acid to reduce its melting point from 65–70 to 30–35 °C and also to produce a reaction mixture with a ratio of free fatty acids (FFA) to sterols close to 2 to improve the progress of sterols esterification. Two enzymatic steps were used in order to separate sterols esterification and ethyl esterification in time and space. The first enzymatic step (in the presence of Candida rugosa lipase) allowed to efficiently transform more than 90% of the original sterols in a short period of time (5 h). The second enzymatic step (in the presence of Novozym 435) converted more than 95% of the FFA in less than 3 h. In addition, the stability of both biocatalysts has been evaluated and both bioprocesses have been scaled-up reutilizing the same batch of lipase up to 8 and 3 times for the first and the second enzymatic step, respectively. The final product obtained is intended to be used as starting material for the purification of sterol esters, tocopherols, and fatty acid ethyl esters via supercritical fluid extraction.     

Glutaraldehyde activation of polymer Nylon-6 for lipase immobilization: enzyme characteristics and stability

An extracellular alkaline lipase of a thermo tolerant Bacillus coagulans BTS-3 was immobilized onto glutaraldehyde activated Nylon-6 by covalent binding. Under optimum conditions, the immobilization yielded a protein loading of 228 microg/g of Nylon-6. Immobilized enzyme showed maximum activity at a temperature of 55 degrees C and pH 7.5. The enzyme was stable between pH 7.5-9.5. It retained 88% of its original activity at 55 degrees C for 2h and also retained 85% of its original activity after eight cycles of hydrolysis of p-NPP. Kinetic parameters Km and Vmax were found to be 4mM and 10 micromol/min/ml, respectively. The influence of organic solvents on the catalytic activity of immobilized enzyme was also evaluated. The bound lipase showed enhanced activity when exposed to n-heptane. The substrate specificity of immobilized enzyme revealed more efficient hydrolysis of higher carbon length (C-16) ester than other ones.     

Immobilization of Burkholderia sp. lipase on a ferric silica nanocomposite for biodiesel production

In this work, lipase produced from an isolated strain Burkholderia sp. C20 was immobilized on magnetic nanoparticles to catalyze biodiesel synthesis. Core-shell nanoparticles were synthesized by coating Fe(3)O(4) core with silica shell. The nanoparticles treated with dimethyl octadecyl [3-(trimethoxysilyl) propyl] ammonium chloride were used as immobilization supporters. The Burkholderia lipase was then bound to the synthesized nanoparticles for immobilization. The protein binding efficiency on alkyl-functionalized Fe(3)O(4)-SiO(2) was estimated as 97%, while the efficiency was only 76% on non-modified Fe(3)O(4)-SiO(2). Maximum adsorption capacity of lipase on alkyl-functionalized Fe(3)O(4)-SiO(2) was estimated as 29.45 mg g(-1) based on Langmuir isotherm. The hydrolytic kinetics (using olive oil as substrate) of the lipase immobilized on alkyl-grafted Fe(3)O(4)-SiO(2) followed Michaelis-Menten model with a maximum reaction rate and a Michaelis constant of 6251 Ug(-1) and 3.65 mM, respectively. Physical and chemical properties of the nanoparticles and the immobilized lipase were characterized by Brunauer-Emmett-Teller (BET) analysis, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR). Moreover, the immobilized lipase was used to catalyze the transesterification of olive oil with methanol to produce fatty acid methyl esters (FAMEs), attaining a FAMEs conversion of over 90% within 30 h in batch operation when 11 wt% immobilized lipase was employed. The immobilized lipase could be used for ten cycles without significant loss in its transesterification activity.     

Pseudomonas cepacia lipase catalyzed esterification and transesterification of 3-(furan-2-yl) propanoic acid/ethyl ester: A comparison in ionic liquids vs hexane

A comparison of the Pseudomonas cepacia lipase (lipase PS) catalyzed esterification of 3-(furan-2-yl) propanoic acid and transesterification of ethyl 3-(furan-2-yl) propanoate with six straight chain alcohols (propanol to octanol) in ionic liquids and hexane was carried out. The ionic liquids selected, [Bmim]BF₄, [Bmim]PF₆, and [Bmim]Tf₂N, consisted of an identical cation and different anions. This is the first report on the biocatalyzed synthesis of these esters. In all the media, lipase PS catalyzed esterification of 3-(furan-2-yl) propanoic acid resulted in high yields of the esters compared to the transesterification of ethyl 3-(furan-2-yl) propanoate. [Bmim]Tf₂N proved to be the best; yielding 98–67% of the product by lipase PS catalyzed esterification. The lipase PS–[Bmim]Tf₂N and lipase PS–[Bmim]PF₆ mixture was recycled five times without any decrease in the yields of the products and was found to be operationally stable up to 10 months at room temperature.     

Enhanced activity and stability of immobilized lipases by treatment with polar solvents prior to lyophilization

Lipases from Candida rugosa, Mucor javanicus and Rhizopus oryzae were respectively adsorbed on Amberlite XAD-7 followed by incubation in 2-propanol and then lyophilization. The activities of the immobilized enzymes were 1.6–3.4 times higher than those of the immobilized enzymes without incubation in the organic solvent before lyophilization for esterification of lauric acid (0.1 M) and 1-propanol (0.1 M) in isooctane at 37 °C. The immobilized C. rugosa lipase (Sigma) without the incubation did not show any activity but displayed considerable activity (19.8 μmol h⁻¹ mg⁻¹) after the incubation before lyophilization. Besides 2-propanol, acetone, 1-propanol and ethyl acetate were also found to be good solvents for treating M. javanicus lipase immobilized on Amberlite XAD-7 and acetone was the best among them. When incubated in isooctane at 25 °C for 120 h, the immobilized M. javanicus lipase prepared by incubation in acetone for 1 h before lyophilization retained 70% of its initial activity while the immobilized enzyme without the solvent treatment kept only 50% of its initial activity.     

Low-temperature lipase from psychrotrophic Pseudomonas sp. strain KB700A

We have previously reported that a psychrotrophic bacterium, Pseudomonas sp. strain KB700A, which displays sigmoidal growth even at -5 degrees C, produced a lipase. A genomic DNA library of strain KB700A was introduced into Escherichia coli TG1, and screening on tributyrin-containing agar plates led to the isolation of the lipase gene. Sequence analysis revealed an open reading frame (KB-lip) consisting of 1,422 nucleotides that encoded a protein (KB-Lip) of 474 amino acids with a molecular mass of 49,924 Da. KB-Lip showed 90% identity with the lipase from Pseudomonas fluorescens and was found to be a member of Subfamily I.3 lipase. Gene expression and purification of the recombinant protein were performed. KB-Lip displayed high lipase activity in the presence of Ca2+. Addition of EDTA completely abolished lipase activity, indicating that KB-Lip was a Ca2+-dependent lipase. Addition of Mn2+ and Sr2+ also led to enhancement of lipase activity but to a much lower extent than that produced by Ca2+. The optimal pH of KB-Lip was 8 to 8.5. The addition of detergents enhanced the enzyme activity. When p-nitrophenyl esters and triglyceride substrates of various chain-lengths were examined, the lipase displayed highest activity towards C10 acyl groups. We also determined the positional specificity and found that the activity was 20-fold higher toward the 1(3) position than toward the 2 position. The optimal temperature for KB-Lip was 35 degrees C, lower than that for any previously reported Subfamily I.3 lipase. The enzyme was also thermolabile compared to these lipases. Furthermore, KB-Lip displayed higher levels of activity at low temperatures than did other enzymes from Subfamily I.3, indicating that KB-Lip has evolved to function in cold environments, in accordance with the temperature range for growth of its psychrotrophic host, strain KB700A.     

Identification of the gene encoding esterase, a homolog of hormone-sensitive lipase, from an oil-degrading bacterium, strain HD-1.

The gene encoding an esterase (HDE) was cloned from an oil-degrading bacterium, strain HD-1. HDE is a member of the hormone-sensitive lipase family and composed of 317 amino acid residues with a molecular weight of 33,633. The HDE-encoding gene was expressed in Escherichia coli, and the recombinant protein was purified and characterized. Amino acid sequence analysis indicated that the methionine residue was removed from its NH(2)-terminus. The good agreement of the molecular weights estimated by SDS-PAGE (35,000) and gel filtration (38,000) suggests that it acts in a monomeric form. HDE showed hydrolytic activity towards p-nitrophenyl esters of fatty acids with an acyl chain length of 2 to 14 and tributyrin, whereas it showed little hydrolytic activity towards p-nitrophenyl oleate (C(18)), tricaprylin and triolein. Determination of the kinetic parameters for the hydrolyses of the p-nitrophenyl substrates from C(2) to C(14) indicated that HDE shows a relatively broad substrate specificity. However, comparison of the k(cat)/K(m) values indicated that the C(10)-C(14) substrates are the most preferred ones. Such a preference for substrates with long acyl chains may be a characteristic of HDE.     

A novel lipase/acyltransferase from the yeast Candida albicans: expression and characterisation of the recombinant enzyme

A gene encoding an extracellular lipase (CaLIP4) from Candida albicans was successfully expressed in Saccharomyces cerevisiae after mutagenesis of its unusual CUG serine codon into a universal one. The ability of this lipase, which shares 60% sequence homology with the lipase/acyltransferase from Candida parapsilosis, to synthesise esters was investigated. CaLIP4 behaved as a true lipase, displaying activity towards insoluble triglycerides and having no activity in the presence of short-chain fatty acid (FA) esters and phosphatidylcholine. Methyl, ethyl and propyl esters were efficiently used. The lipase exhibited highest selectivity for unsaturated FA. With saturated FAs, C14–C16 acyl chains were preferred. In a biphasic aqueous/lipid system, CaLIP4 displayed a high alcoholysis activity with a range of alcohols (e.g. methanol, ethanol, propanol and isopropanol) as acyl acceptor. During the course of the alcoholysis reaction, new esters are produced at concentrations above the thermodynamic equilibrium of the esterification reaction, indicating that ester synthesis does not proceed by esterification but mainly by direct acyltransfer. Ester synthesis is under kinetic control due to the high rate of alcoholysis. Unwanted hydrolysis is limited by competition between the acyl acceptor (alcohol) and water for the acyltransfer reaction, favouring the alcohol.     

Overexpression and characterization of a lipase from Bacillus subtilis

A novel plasmid, pBSR2, was constructed by incorporating a strong lipase promoter and a terminator into the original pBD64. A mature lipase gene from Bacillus subtilis strain IFFI10210, an existing strain for lipase expression, was cloned into the plasmid pBSR2 and transformed into B. subtilis A.S.1.1655. Thus, an overexpression strain, BSL2, was obtained. The yield of lipase is about 8.6 mg protein/g of wet weight of cell mass and 100-fold higher than that in B. subtilis strain IFFI10210. The recombinant lipase was purified in a three-step procedure involving ammonium sulfate fractionation, ion exchange, and gel filtration chromatography. Characterizations of the purified enzyme revealed a molecular mass of 24 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, maximum activity at 43 degrees C and pH 8.5 for hydrolysis of p-nitrophenyl caprylate. The values of Km and Vm were found to be 0.37 mM and 303 micromol mg-1 min-1, respectively. The substrate specificity study showed that p-nitrophenyl caprylate is a preference of the enzyme. The metal ions Ca2+, K+, and Mg2+ can activate the lipase, whereas Fe2+, Cu2+, and Co2+ inhibited it. The activity of the lipase can be increased about 48% by sodium taurocholate at the concentration of 7 mM and inhibited at concentrations over 10 mM.