Easy stabilization of interfacially activated lipases using heterofunctional divinyl sulfone activated-octyl agarose beads. Modulation of the immobilized enzymes by altering their nanoenvironment

Optimizing Thermal Stability: Evaluating the Impact of Heterofunctional Hydrophobic Supports on Immobilized Flaxseed Lipase

Lipases have catalytic capacity in various processes such as hydrolysis. Those derived from plant sources, such as linseed, offer an economical alternative. The immobilization process facilitates the recovery and reuse of lipase, providing advantages such as resistance to high temperatures and difficulties in recovering and reusing free lipases, which makes product separation difficult. This study presents the immobilization of lipases extracted from flax seeds on octylfunctional hydrophobic supports. Additionally, the thermal stability of the derived products was evaluated in comparison with freely soluble lipase. The lipase exhibited a strong affinity for the evaluated heterofunctional hydrophobic supports, with DVS-activated octylagarose emerging as the most efficient method for immobilization, thus increasing catalytic activity upon resuspension. Furthermore, the octylagarose derivative demonstrated a notable increase in thermal stability. The main results of the study include that the soluble enzyme showed greater activity after 24 h, regardless of the temperature evaluated. The benzamide extract showed greater thermal stability, and all supports evaluated showed greater activity than the soluble enzyme after immobilization. Notably, lipase immobilized on octyl glyoxyl agarose showed the highest activity, demonstrated stability for 840 h at 60 °C, and had a half-life of 1242 h. Furthermore, the lipase immobilized in octyl glyoxyl agarose showed a stabilization factor approximately nine times greater than the free enzyme. These results suggest that immobilization, probably achieved through interfacial activation and multipoint covalent bonds, prevented the release of the enzyme into the medium with increasing temperature. This study thus highlights the significant potential of immobilizing flaxseed-derived lipase.

A comprehensive review of lipase-catalyzed acidolysis as a method for producing structured glycerides

The production of structured lipids is a current trend in food technology in order to enhance the properties of fats and oils. Lipases have been utilized in many instances for this purpose, in most examples in an immobilized form. In this review, after discussing the different strategies to produce artificial lipids using lipases (esterification, transesterification, interesterification), we have focused on acidolysis. The reaction commences with hydrolysis at one position of the triglyceride molecule and is followed by the esterification between the released hydroxyl group and the target fatty acid (although other carboxylic acids can be used, such as phenolic acid derivatives). This means that water plays a double role, as substrate in the first step and as an undesired by-product in the second one. Therefore, the control of water activity becomes critical in these reactions. This review discusses the advantages, possibilities and drawbacks of this strategy to produce tailor-made designed lipids, summarizing many of the papers related to this strategy. The summarized results show the complexity of this reaction that can make the understanding and reproducibility of the reactions complex if there are no strict controls of all parameters determining the final yields.

Effect of the support alkyl chain nature in the functional properties of the immobilized lipases

Supports coated with amino-hexyl and amino octyl have been prepared from glyoxyl agarose beads and compared in their performance with octyl-agarose to immobilize lipases A and B from Candida antarctica (CALA and CALB). Immobilization courses were similar using all supports, but enzyme release was more difficult using the amino-alkyl supports suggesting a mixed interfacial activation/ionic exchange immobilization. The enzyme activity and specificity (using p-nitrophenyl propionate, triacetin and both isomers of methyl mandelate) greatly depended on the support. In many instances the enzymes immobilized on the new supports offered higher activities and enantiospecificity in the hydrolysis of both enantiomers of methyl mandelate (mainly using CALB). This was coupled to a lower enzyme stability using the new supports, even in the presence of high ionic strength, suggesting that the amphipathic could be responsible of the enzyme lower stability. Using CALB, it was possible to detect a higher exposition of the enzyme Trp groups to the medium by florescence spectra after its immobilization on the amino-alkyl-supports, correlating to the higher activity and lower stability results.

Changes in ficin specificity by different substrate proteins promoted by enzyme immobilization

Ficin extract has been immobilized using different supports: glyoxyl and Aspartic/1,6 hexamethylenediamine (Asp/HA) agarose beads. The latter was later submitted to glutaraldehyde modification to get covalent immobilization. The activities of these 3 kinds of biocatalysts were compared utilizing 4 different substrates, casein, hemoglobin and bovine serum albumin and benzoyl-arginine-p-nitroanilide at pH 7 and 5. Using glyoxyl-agarose, the effect of enzyme-support reaction time on the activity versus the four substrates at both pH values was studied. Reaction time has been shown to distort the enzyme due to an increase in the number of covalent support-enzyme bonds. Surprisingly, for all the substrates and conditions the prolongation of the enzyme-support reaction did not imply a decrease in enzyme activity. Using the Asp/HA supports (with different amount of HA) differences in the effect on enzyme activity versus the different substrates are much more significant, while with some substrates the immobilization produced a decrease in enzyme activity, with in other cases the activity increased. These different effects are even increased after glutaraldehyde treatment. That way, the conformational changes induced by the biocatalyst immobilization or the chemical modification fully altered the enzyme protein specificity. This may also have some implications when following enzyme inactivation.

Insights on the role of blocking agent on the properties of the lipase from Thermomyces lanuginosus immobilized on heterofunctional support for hydroesterification reactions

Here, we report a study of the effect of the blocking agent on the properties of the lipase from Thermomyces lanuginosus (TLL) immobilized on a heterofunctional support (Purolite C18-ethylnediamina (EDA)- vinyl sulfone (VS)-TLL-blocking agent) in different reactions. The performance of the biocatalysts was compared to those immobilized on standard hydrophobic support (Purolite C18-TLL) and the commercial one (TLL-IM). The nature of the blocking agent (Cys, Gly and Asp) altered the enzyme features. TLL-IM always gave a comparatively worse performance, with its specificity for the oil being very different to the Purolite biocatalysts. Under optimized conditions, Purolite C18-TLL yielded 97 % of hydrolysis conversion after 4 h using a water/waste cooking soybean oil (WCSO) mass ratio of 4.3, biocatalyst load of 6.5 wt% and a temperature of 44.2 °C (without buffer or emulsification agent). In esterification reactions of the purified free fatty acids (FFAs) obtained from WCSO, the best TLL biocatalysts depended on the utilized alcohol: linear amyl alcohol was preferred by Purolite C18-TLL and Purolite C18-EDA-VS-TLL-Gly, while higher activity was achieved utilizing isoamyl alcohol as nucleophile by Purolite C18-EDA-VS-TLL-Cys, Purolite C18-EDA-VS-TLL-Asp and IM-TLL as catalysts. All the results indicate the influence of the blocking step on the final biocatalyst features.

Optimized Spatial Configuration of Heterogeneous Biocatalysts Maximizes Cell-Free Biosynthesis of ω-Hydroxy and ω-Amino Acids

Cell-free biocatalysis is gaining momentum in producing value-added chemicals, particularly in stepwise reaction cascades. However, the stability of enzyme cascades in industrial settings is often compromised when free enzymes are involved. In this study, we have developed a stable multifunctional heterogeneous biocatalyst coimmobilizing five enzymes on microparticles to transform 1,ω-diols into 1,ω-hydroxy acids. We improved the operational efficiency and stability of the heterogeneous biocatalyst by fine-tuning the enzyme loading and spatial organization. Stability issues are overcome through postimmobilization polymer coating. The general applicability of this heterogeneous biocatalyst is demonstrated by its scale-up in both batch and packed bed reactors, allowing a product yield of >80%. The continuous process is fed with H2O2 as the oxygen source, reaching a space-time yield (STY) of 0.76 g·L-1·h-1, maintained for the first 12 h. Finally, this flow system is telescoped with a second plug-flow reactor packed with a different heterogeneous biocatalyst integrating an additional transaminase. As a result, this 6-enzyme 2-reactor system sequentially transforms 1,ω-diols into 1,ω-amino acids while in situ recycling NAD+, depleting H2O2, and generating O2.

Advancements in enzyme immobilization on magnetic nanomaterials: toward sustainable industrial applications

Enzymes are widely used in biofuels, food, and pharmaceuticals. The immobilization of enzymes on solid supports, particularly magnetic nanomaterials, enhances their stability and catalytic activity. Magnetic nanomaterials are chosen for their versatility, large surface area, and superparamagnetic properties, which allow for easy separation and reuse in industrial processes. Researchers focus on the synthesis of appropriate nanomaterials tailored for specific purposes. Immobilization protocols are predefined and adapted to both enzymes and support requirements for optimal efficiency. This review provides a detailed exploration of the application of magnetic nanomaterials in enzyme immobilization protocols. It covers methods, challenges, advantages, and future perspectives, starting with general aspects of magnetic nanomaterials, their synthesis, and applications as matrices for solid enzyme stabilization. The discussion then delves into existing enzymatic immobilization methods on magnetic nanomaterials, highlighting advantages, challenges, and potential applications. Further sections explore the industrial use of various enzymes immobilized on these materials, the development of enzyme-based bioreactors, and prospects for these biocatalysts. In summary, this review provides a concise comparison of the use of magnetic nanomaterials for enzyme stabilization, highlighting potential industrial applications and contributing to manufacturing optimization.

Adsorption features of reduced aminated supports modified with glutaraldehyde: Understanding the heterofunctional features of these supports

Immobilization of enzymes on aminated supports using the glutaraldehyde chemistry may involve three different interactions, cationic, hydrophobic, and covalent interactions. To try to understand the impact this heterofunctionality, we study the physical adsorption of the beta-galactosidase from Aspergillus niger, on aminated supports (MANAE) and aminated supports with one (MANAE-GLU) or two molecules of glutaraldehyde (MANAE-GLU-GLU). To eliminate the chemical reactivity of the glutaraldehyde, the supports were reduced using sodium borohydride. After enzyme adsorption, the release of the enzyme from the supports using different NaCl concentrations, Triton X100, ionic detergents (SDS and CTAB), or different temperatures (4 °C to 55 °C) was studied. Using MANAE support, at 0.3 M NaCl almost all the immobilized enzyme was released. Using MANAE-GLU, 0.3 M, and 0.6 M NaCl similar results were obtained. However, incubation at 1 M or 2 M NaCl, many enzyme molecules were not released from the support. For the MANAE-GLU-GLU support, none of the tested concentrations of NaCl was sufficient to release all enzyme bound to the support. Only using high temperatures, 0.6 M NaCl, and 1 % CTAB or SDS, could the totality of the proteins be released from the support. The results shown in this paper confirm the heterofunctional character of aminated supports modified with glutaraldehyde.

Biocatalytic production of biolubricants: Strategies, problems and future trends

The increasing worries by the inadequate use of energy and the preservation of nature are promoting an increasing interest in the production of biolubricants. After discussing the necessity of producing biolubricants, this review focuses on the production of these interesting molecules through the use of lipases, discussing the different possibilities (esterification of free fatty acids, hydroesterification or transesterification of oils and fats, transesterification of biodiesel with more adequate alcohols, estolides production, modification of fatty acids). The utilization of discarded substrates has special interest due to the double positive ecological impact (e.g., oil distillated, overused oils). Pros and cons of all these possibilities, together with general considerations to optimize the different processes will be outlined. Some possibilities to overcome some of the problems detected in the production of these interesting compounds will be also discussed.

Topochemical Design of Cellulose-Based Carriers for Immobilization of Endoxylanase

Xylooligosaccharides (XOSs) gained much attention for their use in food and animal feed, attributed to their prebiotic function. These short-chained carbohydrates can be enzymatically produced from xylan, one of the most prevalent forms of hemicellulose. In this work, endo-1,4-β-xylanase from Thermotoga maritima was immobilized on cellulose-based beads with the goal of producing xylooligosaccharides with degrees of polymerization (DPs) in the range of 4-6 monomeric units. More specifically, the impact of different spacer arms, tethers connecting the enzyme with the particle, on the expressed enzymatic activity and oligosaccharide yield was investigated. After surface functionalization of the cellulose beads, the presence of amines was confirmed with time of flight secondary ion mass spectrometry (TOF-SIMS), and the influence of different spacer arms on xylanase activity was established. Furthermore, XOSs (DPs 2-6) with up to 58.27 mg/g xylan were obtained, which were greatly enriched in longer oligosaccharides. Approximately 80% of these XOSs displayed DPs between 4 and 6. These findings highlight the importance of topochemical engineering of carriers to influence enzyme activity, and the work puts forward an enzymatic system focusing on the production of longer xylooligosaccharides.

Immobilization of Lipase B from Candida antarctica in Octyl-Vinyl Sulfone Agarose: Effect of the Enzyme-Support Interactions on Enzyme Activity, Specificity, Structure and Inactivation Pathway

Lipase B from Candida antarctica was immobilized on heterofunctional support octyl agarose activated with vinyl sulfone to prevent enzyme release under drastic conditions. Covalent attachment was established, but the blocking step using hexylamine, ethylenediamine or the amino acids glycine (Gly) and aspartic acid (Asp) altered the results. The activities were lower than those observed using the octyl biocatalyst, except when using ethylenediamine as blocking reagent and p-nitrophenol butyrate (pNPB) as substrate. The enzyme stability increased using these new biocatalysts at pH 7 and 9 using all blocking agents (much more significantly at pH 9), while it decreased at pH 5 except when using Gly as blocking agent. The stress inactivation of the biocatalysts decreased the enzyme activity versus three different substrates (pNPB, S-methyl mandelate and triacetin) in a relatively similar fashion. The tryptophane (Trp) fluorescence spectra were different for the biocatalysts, suggesting different enzyme conformations. However, the fluorescence spectra changes during the inactivation were not too different except for the biocatalyst blocked with Asp, suggesting that, except for this biocatalyst, the inactivation pathways may not be so different.

The response surface methodology for optimization of Halomonas sp. C2SS100 lipase immobilization onto CaCO3 for treatment of tuna wash processing wastewater

An immobilized enzyme could exhibit selectively modified physicochemical properties, and it might offer a better environment for the enzyme activity. In this study, the immobilization yield of crude Halomonas sp. lipase was optimized to improve its stability. Thanks to its high adsorption capacity, CaCO₃ has been chosen as support for the immobilization process. Furthermore, response surface methodology (RSM) was used to determine optimal conditions for the immobilization of the bacterial lipase. Five tested factors (enzyme solution, support amount, time, temperature, and acetone volume) were optimized applying a central composite design of RSM. The maximum yield of lipase immobilization was improved to 96%. Furthermore, a biochemical characterization proved a significant improvement of the immobilized lipase stability. The immobilized enzyme is more stable at extreme pH values and high temperatures than the free one. We also tested the reusability of the immobilized lipase by evaluating the recovery of the support using simple filtration. Thanks to its high stability, the immobilized lipase was invested in an effective treatment of tuna wash processing wastewater. The oil biodegradation efficiency was established at 81.5% and was confirmed by Fourier transformation infrared spectrometry. Likewise, the biological oxygen demand values were reduced which makes a possible reduction of the wastewater pollution degree.

Immobilization of Penicillin G Acylase on Vinyl Sulfone-Agarose: An Unexpected Effect of the Ionic Strength on the Performance of the Immobilization Process

Penicillin G acylase (PGA) from Escherichia coli was immobilized on vinyl sulfone (VS) agarose. The immobilization of the enzyme failed at all pH values using 50 mM of buffer, while the progressive increase of ionic strength permitted its rapid immobilization under all studied pH values. This suggests that the moderate hydrophobicity of VS groups is enough to transform the VS-agarose in a heterofunctional support, that is, a support bearing hydrophobic features (able to adsorb the proteins) and chemical reactivity (able to give covalent bonds). Once PGA was immobilized on this support, the PGA immobilization on VS-agarose was optimized with the purpose of obtaining a stable and active biocatalyst, optimizing the immobilization, incubation and blocking steps characteristics of this immobilization protocol. Optimal conditions were immobilization in 1 M of sodium sulfate at pH 7.0, incubation at pH 10.0 for 3 h in the presence of glycerol and phenyl acetic acid, and final blocking with glycine or ethanolamine. This produced biocatalysts with stabilities similar to that of the glyoxyl-PGA (the most stable biocatalyst of this enzyme described in literature), although presenting just over 55% of the initially offered enzyme activity versus the 80% that is recovered using the glyoxyl-PGA. This heterofuncionality of agarose VS beads opens new possibilities for enzyme immobilization on this support.

Switch off/switch on of a cysteinyl protease as a way to preserve the active catalytic group by modification with a reversible covalent thiol modifier: Immobilization of ficin on vinyl-sulfone activated supports

The immobilization of ficin (a cysteinyl proteases) on vinyl sulfone agarose produced its almost full inactivation. It was observed that the incubation of the free and immobilized enzyme in β-mercaptoethanol produced a 20 % of enzyme activity recovery, suggesting that the inactivation due to the immobilization could be a consequence of the modification of the catalytic Cys. To prevent the enzyme inactivation during the immobilization, switching off of ficin via Cys reaction with dipyridyl-disulfide was implemented, giving a reversible disulfide bond that produced a fully inactive enzyme. The switch on of ficin activity was implemented by incubation in 1 M β-mercaptoethanol. Using this strategy to immobilize the enzyme on vinyl sulfone agarose beads, the expressed activity of the immobilized ficin could be boosted up to 80 %. The immobilized enzyme presented a thermal stabilization similar to that obtained using ficin-glyoxyl-agarose beads. This procedure may be extended to many enzymes containing critical Cys, to permit their immobilization or chemical modification.

Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

Enzyme immobilization has been developing since the 1960s and although many industrial biocatalytic processes use the technology to improve enzyme performance, still today we are far from full exploitation of the field. One clear reason is that many evaluate immobilization based on only a few experiments that are not always well-designed. In contrast to many other reviews on the subject, here we highlight the pitfalls of using incorrectly designed immobilization protocols and explain why in many cases sub-optimal results are obtained. We also describe solutions to overcome these challenges and come to the conclusion that recent developments in material science, bioprocess engineering and protein science continue to open new opportunities for the future. In this way, enzyme immobilization, far from being a mature discipline, remains as a subject of high interest and where intense research is still necessary to take full advantage of the possibilities.

Chemical amination of immobilized enzymes for enzyme coimmobilization: Reuse of the most stable immobilized and modified enzyme

Although Lecitase and the lipase from Thermomyces lanuginosus (TLL) could be coimmobilized on octyl-agarose, the stability of Lecitase was lower than that of TLL causing the user to discard active immobilized TLL when Lecitase was inactivated. Here, we propose the chemical amination of immobilized TLL to ionically exchange Lecitase on immobilized TLL, which should be released to the medium after its inactivation by incubation at high ionic strength. Using conditions where Lecitase was only adsorbed on immobilized TLL after its amination, the combibiocatalyst was produced. Unfortunately, the release of Lecitase was not possible using just high ionic strength solutions, and if detergent was added, TLL was also released from the support. This occurred when using 0.25 M ammonium sulfate, Lecitase did not immobilize on aminated TLL. That makes the use octyl-vinylsulfone supports necessary to irreversibly immobilize TLL, and after blocking with ethylendiamine, the immobilized TLL was aminated. Lecitase immobilized and released from this biocatalyst using 0.25 M ammonium sulfate and 0.1% Triton X-100. That way, a coimmobilized TLL and Lecitase biocatalyst could be produced, and after Lecitase inactivation, it could be released and the immobilized, aminated, and fully active TLL could be utilized to build a new combibiocatalyst.

The combination of covalent and ionic exchange immobilizations enables the coimmobilization on vinyl sulfone activated supports and the reuse of the most stable immobilized enzyme

The coimmobilization of lipases from Rhizomucor miehei (RML) and Candida antarctica (CALB) has been intended using agarose beads activated with divinyl sulfone. CALB could be immobilized on this support, while RML was not. However, RML was ionically exchanged on this support blocked with ethylendiamine. Therefore, both enzymes could be coimmobilized on the same particle, CALB covalently using the vinyl sulfone groups, and RML via anionic exchange on the aminated blocked support. However, immobilized RML was far less stable than immobilized CALB. To avoid the discarding of CALB (that maintained 90% of the initial activity after RML inactivation), a strategy was developed. Inactivated RML was desorbed from the support using ammonium sulfate and 1% Triton X-100 at pH 7.0. That way, 5 cycles of RML thermal inactivation, discharge of the inactivated enzyme and re-immobilization of a fresh sample of RML could be performed. In the last cycle, immobilized CALB activity was still over 90% of the initial one. Thus, the strategy permits that enzymes can be coimmobilized on vinyl sulfone supports even if one of them cannot be immobilized on it, and also permits the reuse of the most stable enzyme (if it is irreversibly attached to the support).

Coimmobilization of lipases exhibiting three very different stability ranges. Reuse of the active enzymes and selective discarding of the inactivated ones

Lipase B from Candida antarctica (CALB) and lipases from Candida rugosa (CRL) and Rhizomucor miehei (RML) have been coimmobilized on octyl and octyl-Asp agarose beads. CALB was much more stable than CRL, that was significantly more stable than RML. This forces the user to discard immobilized CALB and CRL when only RML has been inactivated, or immobilized CALB when CRL have been inactivated. To solve this problem, a new strategy has been proposed using three different immobilization protocols. CALB was covalently immobilized on octyl-vinyl sulfone agarose and blocked with Asp. Then, CRL was immobilized via interfacial activation. After coating both immobilized enzymes with polyethylenimine, RML could be immobilized via ion exchange. That way, by incubating in ammonium sulfate solutions, inactivated RML could be released enabling the reuse of coimmobilized CRL and CALB to build a new combi-lipase. Incubating in triton and ammonium sulfate solutions, it was possible to release inactivated CRL and RML, enabling the reuse of immobilized CALB when CRL was inactivated. These cycles could be repeated for 3 full cycles, maintaining the activity of the active and immobilized enzymes.

Enzyme-support interactions and inactivation conditions determine Thermomyces lanuginosus lipase inactivation pathways: Functional and florescence studies

Lipase from Thermomyces lanuginosus (TLL) has been covalently immobilized on heterofunctional octyl-vinyl agarose. That way, the covalently immobilized enzymes will have identical orientation. Then, it has blocked using hexyl amine (HEX), ethylenediamine (EDA), Gly and Asp. The initial activity/stability of the different biocatalysts was very different, being the most stable the biocatalyst blocked with Gly. These biocatalysts had been utilized to analyze if the enzyme activity could decrease differently along thermal inactivation courses depending on the utilized substrate (that is, if the enzyme specificity was altered during its inactivation using 4 different substrates to determine the activity), and if this can be altered by the nature of the blocking agent and the inactivation conditions (we use pH 5, 7 and 9). Results show great changes in the enzyme specificity during inactivation (e.g., activity versus triacetin was much more quickly lost than versus the other substrates), and how this was modulated by the immobilization protocol and inactivation conditions. The difference in the changes induced by immobilization and inactivation were confirmed by fluorescence studies. That is, the functional and structural analysis of partially inactivated immobilized enzyme showed that their inactivation pathway is strongly depended on the support features and inactivation conditions.

Chemical modification of enzymes to improve biocatalytic performance

Improvement in intrinsic enzymatic features is in many instances a prerequisite for the scalable applicability of many industrially important biocatalysts. To this end, various strategies of chemical modification of enzymes are maturing and now considered as a distinct way to improve biocatalytic properties. Traditional chemical modification methods utilize reactivities of amine, carboxylic, thiol and other side chains originating from canonical amino acids. On the other hand, noncanonical amino acid- mediated 'click' (bioorthogoal) chemistry and dehydroalanine (Dha)-mediated modifications have emerged as an alternate and promising ways to modify enzymes for functional enhancement. This review discusses the applications of various chemical modification tools that have been directed towards the improvement of functional properties and/or stability of diverse array of biocatalysts.

Stabilization of enzymes via immobilization: Multipoint covalent attachment and other stabilization strategies

The use of enzymes in industrial processes requires the improvement of their features in many instances. Enzyme immobilization, a requirement to facilitate the recovery and reuse of these water-soluble catalysts, is one of the tools that researchers may utilize to improve many of their properties. This review is focused on how enzyme immobilization may improve enzyme stability. Starting from the stabilization effects that an enzyme may experience by the mere fact of being inside a solid particle, we detail other possibilities to stabilize enzymes: generation of favorable enzyme environments, prevention of enzyme subunit dissociation in multimeric enzymes, generation of more stable enzyme conformations, or enzyme rigidification via multipoint covalent attachment. In this last point, we will discuss the features of an "ideal" immobilization protocol to maximize the intensity of the enzyme-support interactions. The most interesting active groups in the support (glutaraldehyde, epoxide, glyoxyl and vinyl sulfone) will be also presented, discussing their main properties and uses. Some instances in which the number of enzyme-support bonds is not directly related to a higher stabilization will be also presented. Finally, the possibility of coupling site-directed mutagenesis or chemical modification to get a more intense multipoint covalent immobilization will be discussed.

Multi-Combilipases: Co-Immobilizing Lipases with Very Different Stabilities Combining Immobilization via Interfacial Activation and Ion Exchange. The Reuse of the Most Stable Co-Immobilized Enzymes after Inactivation of the Least Stable Ones

The lipases A and B from Candida antarctica (CALA and CALB), Thermomyces lanuginosus (TLL) or Rhizomucor miehei (RML), and the commercial and artificial phospholipase Lecitase ultra (LEU) may be co-immobilized on octyl agarose beads. However, LEU and RML became almost fully inactivated under conditions where CALA, CALB and TLL retained full activity. This means that, to have a five components co-immobilized combi-lipase, we should discard 3 fully active and immobilized enzymes when the other two enzymes are inactivated. To solve this situation, CALA, CALB and TLL have been co-immobilized on octyl-vinyl sulfone agarose beads, coated with polyethylenimine (PEI) and the least stable enzymes, RML and LEU have been co-immobilized over these immobilized enzymes. The coating with PEI is even favorable for the activity of the immobilized enzymes. It was checked that RML and LEU could be released from the enzyme-PEI coated biocatalyst, although this also produced some release of the PEI. That way, a protocol was developed to co-immobilize the five enzymes, in a way that the most stable could be reused after the inactivation of the least stable ones. After RML and LEU inactivation, the combi-biocatalysts were incubated in 0.5 M of ammonium sulfate to release the inactivated enzymes, incubated again with PEI and a new RML and LEU batch could be immobilized, maintaining the activity of the three most stable enzymes for at least five cycles of incubation at pH 7.0 and 60 °C for 3 h, incubation on ammonium sulfate, incubation in PEI and co-immobilization of new enzymes. The effect of the order of co-immobilization of the different enzymes on the co-immobilized biocatalyst activity was also investigated using different substrates, finding that when the most active enzyme versus one substrate was immobilized first (nearer to the surface of the particle), the activity was higher than when this enzyme was co-immobilized last (nearer to the particle core).

Rhizomucor miehei lipase-catalysed synthesis of cocoa butter equivalent from palm mid-fraction and stearic acid: Characteristics and feasibility as cocoa butter alternative

In this study, cocoa butter equivalents (CBEs) were prepared through enzymatic interesterification of palm mid-fraction (PMF) with stearic acid (SA). The reaction process parameters were experimented and the performance of the product was analysed. PMF and stearic acid (at a mass ratio of 1:2) were catalysed by 80 g kg^-1 enzyme loading of Lipozyme RM IM fromRhizomucor mieheiat 60 °C for 120 min. The yield of the CBE product was more than 92%, and the CBE resembled cocoa butter (CB) in terms of its triacylglycerol composition. The hardness of the CBE product was higher than that of CB at different storage temperatures, but this difference was not obvious at 25 °C. The polymorphic structures and SFC curve of the CBE were similar to those of the CB. In addition, the CBE could be mixed with CB in any ratio without an obvious eutectic phenomena. Up to 40% CBE could be added to CB without significantly affecting the thermodynamic properties of CB. Thus, replacing CB with the CBE product is feasible.

Enzyme-Coated Micro-Crystals: An Almost Forgotten but Very Simple and Elegant Immobilization Strategy

The immobilization of enzymes using protein coated micro-crystals (PCMCs) was reported for the first time in 2001 by Kreiner and coworkers. The strategy is very simple. First, an enzyme solution must be prepared in a concentrated solution of one compound (salt, sugar, amino acid) very soluble in water and poorly soluble in a water-soluble solvent. Then, the enzyme solution is added dropwise to the water soluble solvent under rapid stirring. The components accompanying the enzyme are called the crystal growing agents, the solvent being the dehydrating agent. This strategy permits the rapid dehydration of the enzyme solution drops, resulting in a crystallization of the crystal formation agent, and the enzyme is deposited on this crystal surface. The reaction medium where these biocatalysts can be used is marked by the solubility of the PCMC components, and usually these biocatalysts may be employed in water soluble organic solvents with a maximum of 20% water. The evolution of these PCMC was to chemically crosslink them and further improve their stabilities. Moreover, the PCMC strategy has been used to coimmobilize enzymes or enzymes and cofactors. The immobilization may permit the use of buffers as crystal growth agents, enabling control of the reaction pH in the enzyme environments. Usually, the PCMC biocatalysts are very stable and more active than other biocatalysts of the same enzyme. However, this simple (at least at laboratory scale) immobilization strategy is underutilized even when the publications using it systematically presented a better performance of them in organic solvents than that of many other immobilized biocatalysts. In fact, many possibilities and studies using this technique are lacking. This review tried to outline the possibilities of this useful immobilization strategy.

One Pot Use of Combilipases for Full Modification of Oils and Fats: Multifunctional and Heterogeneous Substrates

Lipases are among the most utilized enzymes in biocatalysis. In many instances, the main reason for their use is their high specificity or selectivity. However, when full modification of a multifunctional and heterogeneous substrate is pursued, enzyme selectivity and specificity become a problem. This is the case of hydrolysis of oils and fats to produce free fatty acids or their alcoholysis to produce biodiesel, which can be considered cascade reactions. In these cases, to the original heterogeneity of the substrate, the presence of intermediate products, such as diglycerides or monoglycerides, can be an additional drawback. Using these heterogeneous substrates, enzyme specificity can promote that some substrates (initial substrates or intermediate products) may not be recognized as such (in the worst case scenario they may be acting as inhibitors) by the enzyme, causing yields and reaction rates to drop. To solve this situation, a mixture of lipases with different specificity, selectivity and differently affected by the reaction conditions can offer much better results than the use of a single lipase exhibiting a very high initial activity or even the best global reaction course. This mixture of lipases from different sources has been called “combilipases” and is becoming increasingly popular. They include the use of liquid lipase formulations or immobilized lipases. In some instances, the lipases have been coimmobilized. Some discussion is offered regarding the problems that this coimmobilization may give rise to, and some strategies to solve some of these problems are proposed. The use of combilipases in the future may be extended to other processes and enzymes.

Immobilized microbial lipases in the food industry: a systematic literature review

Several studies describe the immobilization of microbial lipases aiming to evaluate the mechanical/thermal stability of the support/enzyme system, the appropriate method for immobilization, acid and alkaline stability, tolerance to organic solvents and specificity of fatty acids. However, literature reviews focus on application of enzyme/support system in food technology remains scarce. This current systematic literature review aimed to identify, evaluate and interpret available and relevant researches addressing the type of support and immobilization techniques employed over lipases, in order to obtain products for food industry. Fourteen selected articles were used to structure the systematic review, in which the discussion was based on six main groups: (i) synthesis/enrichment of polyunsaturated fatty acids; (ii) synthesis of structured lipids; (iii) flavors and food coloring; (iv) additives, antioxidants and antimicrobials; (v) synthesis of phytosterol esters and (vi) synthesis of sugar esters. In general, the studies discussed the synthesis of the enzyme/support system and the characteristics: surface area, mass transfer resistance, activity, stability (pH and temperature), and recyclability. Each immobilization technique is applicable for a specific production, depending mainly on the sensitivity and cost of the process.

Preparation of immobilized/stabilized biocatalysts of β-glucosidases from different sources: Importance of the support active groups and the immobilization protocol

β-Glucosidases from two different commercial preparations, Pectinex Ultra SP-L and Celluclast® 1.5L, were immobilized on divinylsulfone (DVS) supports at pH 5.0, 7.0, 9.0, and 10. In addition, the biocatalysts were also immobilized in agarose beads activated by glyoxyl, and epoxide as reagent groups. The best immobilization results were observed using higher pH values on DVS-agarose, and for Celluclast® 1.5L, good results were also obtained using the glyoxil-agarose immobilization. The biocatalyst obtained using Pectinex Ultra SP-L showed the highest thermal stability, at 65°C, and an operational stability of 67% of activity after 10 reuses cycles when immobilized on DVS-agarose immobilized at pH 10 and blocked with ethylenediamine. The β-glucosidase from Celluclast® 1.5L produced best results when immobilized on DVS-agarose immobilized at pH 9 and blocked with glycine, reaching 7.76-fold higher thermal stability compared to its free form and maintaining 76% of its activity after 10 successive cycles. The new biocatalysts obtained by these protocols showed reduction of glucose inhibition of enzymes, demonstrating the influence of immobilization protocols, pH, and blocking agent.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.

Production of Omegas-6 and 9 from the Hydrolysis of Açaí and Buriti Oils by Lipase Immobilized on a Hydrophobic Support

This paper describes a bioprocess to obtain omegas-6 and 9 from the hydrolysis of Açaí (Euterpe oleracea Martius) and Buriti (Mauritia flexuosa) oils by lipases immobilized on octyl-sepharose. For this, oils and butters were initially selected as the carbon source which resulted in higher production of lipases in Beauveria bassiana and Fusarium oxysporum cultures. The carbon source that provided secretion of lipase by B. bassiana was Açaí oil, and for F. oxysporum, Bacuri butter. Lipases obtained under these conditions were immobilized on octyl-sepharose, and both, the derivatives and the crude extracts were biochemically characterized. It was observed that the immobilization promoted an increase of stability in B. bassiana and F. oxysporum lipase activities at the given temperatures and pH. In addition, the immobilization promoted hyperactivation of B. bassiana and F. oxysporum lipase activities being 23.5 and 11.0 higher than free enzyme, respectively. The hydrolysis of Açaí and Buriti oils by the derivatives was done in a biphasic (organic/aqueous) system, and the products were quantified in RP-HPLC. The results showed the potential of these immobilized lipases to obtain omegas-6 and 9 from Brazilian natural oils. This work may improve the enzymatic methodologies for obtaining foods and drugs enriched with fatty acids.