Rahman RNZ. Spray-dried immobilized lipase from Geobacillus sp. strain ARM in sago

Sago starch is traditionally used as food especially in Southeast Asia. Generally, sago is safe for consumption, biodegradable, easily available and inexpensive. Therefore, this research was done to expand the potential of sago by using it as a support for enzyme immobilization. In this study, ARM lipase, which was isolated from Geobacillus sp. strain ARM, was overexpressed in Escherichia coli system and then purified using affinity chromatography. The specific activity of the pure enzyme was 650 U/mg, increased 7 folds from the cell lysate. The purified enzyme was immobilized in gelatinized sago and spray-dried by entrapment technique in order to enhance the enzyme operational stability for handling at high temperature and also for storage. The morphology of the gelatinized sago and immobilized enzyme was studied by scanning electron microscopy. The results showed that the spray-dried gelatinized sago was shrunken and became irregular in structure as compared to untreated sago powder. The surface areas and porosities of spray-dried gelatinized sago with and without the enzyme were analyzed using BET and BJH method and have shown an increase in surface area and decrease in pore size. The immobilized ARM lipase showed good performance at 60-80  °C, with a half-life of 4 h and in a pH range 6-9. The immobilized enzyme could be stored at 10 °C with the half-life for 9 months. Collectively, the spray-dried immobilized lipase shows promising capability for industrial uses, especially in food processing.

Artificial Nanometalloenzymes for Cooperative Tandem Catalysis

Artificial metalloenzymes that combine the advantages of natural enzymes and metal catalysts have been getting more attention in research. As a proof of concept, an artificial nanometalloenzyme (CALB-Shvo@MiMBN) was prepared by co-encapsulation of metallo-organic catalyst and enzyme in a soft nanocomposite consisting of 2-methylimidazole, metal ions, and biosurfactant in mild reaction conditions using a one-pot self-assembly method. The artificial nanometalloenzyme with lipase acted as the core, and the metallo-organic catalyst embedded in micropore exhibited a spherical structure of 30-50 nm in diameter. The artificial nanometalloenzyme showed high catalytic efficiency in the dynamic kinetic resolution of racemic primary amines or secondary alcohols compared to the one-pot catalytic reaction of immobilized lipase and free metallo-organic catalyst. This artificial nanometalloenzyme holds great promise for integrated enzymatic and heterogeneous catalysis.

Tuning Pore Heterogeneity in Covalent Organic Frameworks for Enhanced Enzyme Accessibility and Resistance against Denaturants

Achieving high-performance biocomposites requires knowledge of the compatability between the immobilized enzyme and its host material. The modular nature of covalent organic frameworks (COFs), as a host, allows their pore geometries and chemical functionalities to be fine-tuned independently, permitting comparative studies between the individual parameters and the performances of the resultant biocomposites. This research demonstrates that dual pores in COFs have profound consequences on the catalytic activity and denaturation of infiltrated enzymes. This approach enforces a constant pore environment by rational building-block design, which enables it to be unequivocally determined that pore heterogeneity is responsible for rate enhancements of up to threefold per enzyme molecule. More so, the enzyme is more tolerant to detrimental by-products when occupying the larger pore in a dual-pore COF compared to a corresponding uniform porous COF. Kinetic studies highlight that pore heterogeneity facilitates mass transfer of both reagents and products. This unparalleled versatility of these materials allows many different aspects to be designed on demand, lending credence to their prospect as next-generation host materials for various enzyme biocomposites catalysts.

Enhanced Biocatalytic Activity of Recombinant Lipase Immobilized on Gold Nanoparticles

BACKGROUND

Bacterial lipases especially Pseudomonas lipases are extensively used for different biotechnological applications.

OBJECTIVES

With the better understanding and progressive needs for improving its activity in accordance with the growing market demand, we aimed in this study to improve the recombinant production and biocatalytic activity of lipases via surface conjugation on gold nanoparticles.

METHODS

The full length coding sequences of lipase gene (lipA), lipase specific foldase gene (lipf) and dual cassette (lipAf) gene were amplified from the genomic DNA of Pseudomonas aeruginosa PA14 and cloned into the bacterial expression vector pRSET-B. Recombinant lipases were expressed in E. coli BL-21 (DE3) pLysS then purified using nickel affinity chromatography and the protein identity was confirmed using SDS-PAGE and Western blot analysis. The purified recombinant lipases were immobilized through surface conjugation with gold nanoparticles and enzymatic activity was colorimetrically quantified.

RESULTS

Here, two single expression plasmid systems pRSET-B-lipA and pRSET-B-lipf and one dual cassette expression plasmid system pRSET-B-lipAf were successfully constructed. The lipolytic activities of recombinant lipases LipA, Lipf and LipAf were 4870, 426 and 6740 IUmg-1, respectively. However, upon immobilization of these recombinant lipases on prepared gold nanoparticles (GNPs), the activities were 7417, 822 and 13035 IUmg-1, for LipA-GNPs, Lipf-GNPs and LipAf-GNPs, respectively. The activities after immobilization have been increased 1.52 and 1.93 -fold for LipA and LipAf, respectively.

CONCLUSION

The lipolytic activity of recombinant lipases in the bioconjugate was significantly increased relative to the free recombinant enzyme where immobilization had made the enzyme attain its optimum performance.

Directly covalent immobilization of Candida antarctica lipase B on oxidized aspen powder by introducing poly‑lysines: An economical approach to improve enzyme performance

In our previous study, we could achieve high soluble expression of Candida antarctica lipase B (CalB) in E. coli by fusion poly‑amino acid tags on CalB (pCalB). Herein, we are surprised to find that pCalB can be easily and directly covalent binding on a simply oxidized aspen powder (OAP) by the aid of poly‑lysine tags. Under the optimal conditions, 72.9 ± 3.6% of the total protein could be immobilized, and the activity recovery of immobilized pCalB (pCalB-OAP) was 98.9 ± 3.8%. The analysis of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) indicated that OAP was a suitable carrier for enzyme immobilization. The immobilized pCalB-OAP could exhibit excellent thermal stabilities, and it retained a residual activity of 58.4 ± 2.8% at 55 °C, whereas only 21.2 ± 2.2% of its initial activity for free pCalB was observed. And it could also display a nice tolerance for the changes of pH environment, compared with that of free pCalB. The results that pCalB-OAP could retained 73.6 ± 2.9% of their initial activity in (R, S)-NEMPAME hydrolysis after the tenth cycles, suggested that pCalB-OAP could be effectively recycled. The immobilization strategies established here were simple and inexpensive.

Direct enzymatic ethanolysis of potential Nannochloropsis biomass for co-production of sustainable biodiesel and nutraceutical eicosapentaenoic acid

BACKGROUND

Marine microalga Nannochloropsis is a promising source for the production of renewable and sustainable biodiesel in replacement of depleting petroleum. Other than biodiesel, Nannochloropsis is a green and potential resource for the commercial production of nutraceutical eicosapentaenoic acid (EPA, C_20:5). In recent studies, low-value biodiesel can be achieved by transesterification of Nannochloropsis biomass. However, it is undoubtedly wasteful to produce microalgal biodiesel containing EPA from nutritional and economical aspects. A new strategy was addressed and exploited to produce low-value bulky biodiesel along with EPA enrichment via enzymatic ethanolysis of Nannochloropsis biomass with a specific lipase.

RESULTS

Cellulase pretreatment on Nannochloropsis sp. biomass significantly improved the biodiesel conversion by direct ethanolysis with five enzymes from Candida antarctica (CALA and CALB), Thermomyces lanuginosus (TL), Rhizomucor miehei (RM), and Aspergillus oryzae (PLA). Among these five biocatalysts, CALA was the best suitable enzyme to yield high biodiesel conversion and effectively enrich EPA. After optimization, the maximum biodiesel conversion (46.53-48.57%) was attained by CALA at 8:1 ethanol/biomass ratio (v/w) in 10-15% water content with 10% lipase weight at 35 °C for 72 h. Meanwhile, EPA (60.81%) was highly enriched in microalgae NPLs (neutral lipids and polar lipids), increasing original EPA levels by 1.51-fold. Moreover, this process was re-evaluated with two Nannochloropsis species (IMET1 and Salina 537). Under the optimized conditions, the biodiesel conversions of IMET1 and Salina 537 by CALA were 63.41% and 54.33%, respectively. EPA contents of microalgal NPLs were 50.06% for IMET1 and 53.73% for Salina 537.

CONCLUSION

CALA was the potential biocatalyst to discriminate against EPA in the ethanolysis of Nannochloropsis biomass. The biodiesel conversion and EPA enrich efficiency of CALA were greatly dependent on lipidic class and fatty acid compositions of Nannochloropsis biomass. CALA-catalyzed ethanolysis with Nannochloropsis biomass was a promising approach for co-production of low-value biodiesel and high-value microalgae products rich in EPA.

Effect of the Immobilization Strategy on the Efficiency and Recyclability of the Versatile Lipase from Ophiostoma piceae

The recombinant lipase from Ophiostoma piceae OPEr has demonstrated to have catalytic properties superior to those of many commercial enzymes. Enzymatic crudes with OPEr were immobilized onto magnetite nanoparticles by hydrophobicity (SiMAG-Octyl) and by two procedures that involve covalent attachment of the protein (mCLEAs and AMNP-GA), giving three nanobiocatalysts with different specific activity in hydrolysis of p-nitrophenyl butyrate (pNPB) and good storage stability at 4 °C over a period of 4 months. Free OPEr and the different nanobiocatalysts were compared for the synthesis of butyl esters of volatile fatty acids C4 to C7 in reactions containing the same lipase activity. The esterification yields and the reaction rates obtained with AMNP-GA-OPEr were in general higher or similar to those observed for the free enzyme, the mCLEAs-OPEr, and the non-covalent preparation SiMAG-Octyl-OPEr. The time course of the esterification of the acids C4 to C6 catalyzed by AMNP-GA-OPEr was comparable. The synthesis of the C7 ester was slower but very efficient, admitting concentrations of heptanoic acid up to 1 M. The best 1-butanol: acid molar ratio was 2:1 for all the acids tested. Depending on the substrate, this covalent preparation of OPEr maintained 80–96% activity over 7 cycles, revealing its excellent properties, easy recovery and recycling, and its potential to catalyze the green synthesis of chemicals of industrial interest.

Critical applications of Mucor circinelloides within a biorefinery context

The establishment of an efficient and feasible biorefinery model depends on, among other factors, particularly the selection of the most appropriate microorganism. Mucor circinelloides is a dimorphic fungus species able to produce a wide variety of hydrolytic enzymes, lipids prone to biodiesel production, carotenoids, ethanol, and biomass with significant nutritional value. M. circinelloides also has been selected as a model species for genetic modification by being the first filamentous oleaginous species to have its genome fully characterized, as well as being a species characterized as a potential bioremediation agent. Considering the potential of replacing several nonrenewable feedstocks is widely dependent on fossil fuels, the exploitation of microbial processes and products is a desirable solution for promoting a green and sustainable future. Here, we introduce and thoroughly describe the recent and critical applications of this remarkable fungus within the context of developing a fungal-based biorefinery.

Biochemical profiles of two thermostable and organic solvent-tolerant esterases derived from a compost metagenome

Owing to the functional versatility and potential applications in industry, interest in lipolytic enzymes tolerant to organic solvents is increasing. In this study, functional screening of a compost soil metagenome resulted in identification of two lipolytic genes, est1 and est2, encoding 270 and 389 amino acids, respectively. The two genes were heterologously expressed and characterized. Est1 and Est2 are thermostable enzymes with optimal enzyme activities at 80 and 70 °C, respectively. A second-order rotatable design, which allows establishing the relationship between multiple variables with the obtained responses, was used to explore the combined effects of temperature and pH on esterase stability. The response curve indicated that Est1, and particularly Est2, retained high stability within a broad range of temperature and pH values. Furthermore, the effects of organic solvents on Est1 and Est2 activities and stabilities were assessed. Notably, Est2 activity was significantly enhanced (two- to tenfold) in the presence of ethanol, methanol, isopropanol, and 1-propanol over a concentration range between 6 and 30% (v/v). For the short-term stability (2 h of incubation), Est2 exhibited high tolerance against 60% (v/v) of ethanol, methanol, isopropanol, DMSO, and acetone, while Est1 activity resisted these solvents only at lower concentrations (below 30%, v/v). Est2 also displayed high stability towards some water-immiscible organic solvents, such as ethyl acetate, diethyl ether, and toluene. With respect to long-term stability, Est2 retained most of its activity after 26 days of incubation in the presence of 30% (v/v) ethanol, methanol, isopropanol, DMSO, or acetone. All of these features indicate that Est1 and Est2 possess application potential.

All Wrapped up: Stabilization of Enzymes within Single Enzyme Nanoparticles

Enzymes are extremely useful in many industrial and pharmaceutical areas due to their ability to catalyze reactions with high selectivity. In order to extend their lifetime, significant efforts have been made to increase their stability using protein- or medium engineering as well as by chemical modification. Many researchers have explored the immobilization of enzymes onto carriers, or entrapment within a matrix, framework or nanoparticle with the hope of constricting the movement of the enzyme and shielding it from aggressive environments, thus delaying the denaturation. These strategies often balance three competing interests: (i) maintaining high enzymatic activity, (ii) ensuring good long-term stability against temperature, dehydration, organic solvents, and or aggressive pH, and (iii) enabling a tuning or reversible switching of enzyme activity. In most cases, multiple enzymes will be contained within a single nanoparticle or matrix, but in recent years researchers have begun to wrap up individual enzymes within single enzyme nanoparticles (SENs). In these nanoparticles the enzyme is stabilized by a thin shell, typically a polymer, prepared either by in situ polymerization from the enzyme surface or by assembling a preformed polymer around it. Because of the increased control over the environment directly around the enzyme, and the possibility of more directly controlling substrate diffusion, many SENs show remarkable stability while retaining high initial activities even for quite fragile enzymes. Moreover, the activity of the enzyme can often be more easily fine-tuned by adjusting the layer properties. We postulate that this emerging field will offer exciting and elegant opportunities to both extend the catalytic lifetime of enzymes in aggressive solvents, temperatures and pH, and enable their activity to be switched on and off on demand by modulation of the outer material layer.

A combination of absorption and enzymatic biodegradation: phenol elimination from aqueous and organic phase

Peroxidase from Brassica rapa was immobilized as cross-linked enzyme aggregates (CLEAs) and used to treat air containing phenol as a model molecule of volatile organic compounds (VOCs). Prior to an enzymatic treatment, phenol was absorbed into an aqueous or organic phase (silicone oil) to reach concentrations ranging from 20 to 160 mg/L. The process was carried out by introducing a desired weighing of BRP-CLEAs into preparations and reaction was started by injecting H₂O₂ solution to the medium. Optimization of the reaction conditions in the organic solvent revealed an optimal contact time of 60 min, 60 mg/L of phenol concentration and 3 mM H₂O₂, leading to a maximum removal yield of 70% for 3.4 UI/mL of BRP-CLEAs. These results were compared to those obtained in an aqueous medium that showed 90% of degradation yield after 40 min in the following conditions, 90 mg/L of initial phenol amount, 2 mM of H₂O₂ and 2.5 UI/mL of BRP-CLEAs. Parameters of the Michaelis-Menten model, Km and Vmax, were also determined for the reaction in both phases. Phenol removal by BRP-CLEAs in silicone oil succeeded with 70% of conversion yield. It is promising regarding the transposition of such enzymatic process to hydrophobic VOCs.

Preparation of Crosslinked Enzyme Aggregates of a Thermostable Cyclodextrin Glucosyltransferase from Thermoanaerobacter sp. Critical Effect of the Crosslinking Agent

Crosslinked enzyme aggregates (CLEAs) of a thermostable cyclodextrin glucosyltransferase (CGTase) from Thermoanaerobacter sp. have been prepared for the production of cyclodextrins (CDs). Different parameters in the precipitation (nature and concentration of precipitant) and crosslinking steps (time of reaction with cross-linker, nature and concentration of the crosslinker) were evaluated on the production of CLEAs of CGTase. Among the seven studied precipitants, acetone with a 75% (v/v) concentration produced the aggregates of CGTase with higher activity, which retained 97% of the initial activity. Concerning the cross-linker (glutaraldehyde, starch–aldehyde, and pectin–aldehyde), starch–aldehyde produced the most active CLEAs. The use of bovine serum albumin as co-feeder decreased the expressed activity. Addition of polyethylenimine at the end of cross-linking step prevented the leakage of the enzyme and the subsequent Schiff’s bases reduction with sodium borohydride permitted to maintain 24% of the initial activity even with the large dextrin as substrate. The optimal conditions for the immobilization process required were defined as 75% (v/v) acetone as precipitation reagent for 1 h at 20 °C, 20 mM starch–aldehyde as crosslinking reagent for 2 h at 20 °C, treatment with 1 mg/mL of polyethylenimine for 5 min, reduction with 1 mg/mL of sodium borohydride. The CLEAs of CGTase were active catalyst (similarly to the free enzyme) in the production of cyclodextrins at 50 °C and pH 6.0 for 6 h reaction, maintaining intact their structures. Besides this, after five cycles of 3 h the total cyclodextrin yield was 80% of the initial value (first batch, with around 45% CD yield).

A fluorescence-based activity assay for immobilized lipases in non-native media

A new method for the analysis of lipase activity in the immobilized state is developed. The fluorescence assay aims to quantify the potential of lipases for the application in organic solvents. As lipases are universally immobilized on polymeric carriers for the use in bioorganic synthesis, the assay includes an immobilization step on the walls of polymeric cuvettes. The activity of the immobilized lipase is probed by 4-methylumbelliferyl ester hydrolysis. The activity retention as a function of solvent concentration is used as a measure for the solvent resistance of the enzyme variant. The method is applied to two different lipases, Candida antarctica lipase B (CalB) and Bacillus subtilis lipase A (BSLA) in the presence of the solvents acetonitrile and ethanol. By comparison of the assay results with a commercial biocatalyst consisting of CalB on polymeric carrier (Novozyme 435) it is demonstrated that the assay allows a good prediction of the activity of the respective lipase as immobilisate on polymeric carriers. The assay surpasses the respective analysis in solution in terms of accuracy and precision.

Enzymatic synthesis of enantiopure alcohols: current state and perspectives

Enantiomerically pure alcohols, as key intermediates, play an essential role in the pharmaceutical, agrochemical and chemical industries. Among the methods used for their production, biotechnological approaches are generally considered a green and effective alternative due to their mild reaction conditions and remarkable enantioselectivity. An increasing number of enzymatic strategies for the synthesis of these compounds has been developed over the years, among which seven primary methodologies can be distinguished as follows: (1) enantioselective water addition to alkenes, (2) enantioselective aldol addition, (3) enantioselective coupling of ketones with hydrogen cyanide, (4) asymmetric reduction of carbonyl compounds, (5) (dynamic) kinetic resolution of racemates, (6) enantioselective hydrolysis of epoxides, and (7) stereoselective hydroxylation of unactivated C-H bonds. Some recent reviews have examined these approaches separately; however, to date, no review has included all the above mentioned strategies. The aim of this mini-review is to provide an overview of all seven enzymatic strategies and draw conclusions on the effect of each approach.

Characterization and application of chemical-resistant polyurethane-based enzyme and whole cell compartments

This study presents the preparation and physical-chemical characterization of chemical resistant polyurethane-based compartments for biocatalytic application. The artificial compartments were prepared from an emulsion of polymer precursor and an aqueous phase that includes a biocatalytic reaction system. After curing, highly dispersed aqueous domains were obtained, which still contain the entire biocatalytic reaction system and remain fixed in the solid polymer preparation. The tensile and compression behavior of the prepared polymeric material is not significantly affected by the incorporation and facilitates excellent stability against various organic solvents and acid solutions. Thereby, the compartments can be used not only for enantioselective alcohol-dehydrogenase catalyzed reduction but also for a whole cell catalyzed hydrolysis of esters. Moreover, the compartmented whole-cell system was considerably stable to allow multiple reuses without a noticeable loss of catalytic activity of the incorporated whole cell catalytic reaction system.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

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

Crackled nanocapsules: the “imperfect” structure for enzyme immobilization

Crackled organosilica nanocapsules (CONs) are prepared using a metal–organic framework (MOF) hard-templating method to directly immobilize enzymes without post modification.

Continuous flow kinetic resolution of a non-equimolar mixture of diastereoisomeric alcohol using a structured monolithic enzymatic microreactor

A remarkable space-time yield value of about 100 g h⁻¹ L⁻¹ has been achieved for the developed system.

Solvent stable microbial lipases: current understanding and biotechnological applications

OBJECTIVE

This review examines on our current understanding of microbial lipase solvent tolerance, with a specific focus on the molecular strategies employed to improve lipase stability in a non-aqueous environment.

RESULTS

It provides an overview of known solvent tolerant lipases and of approaches to improving solvent stability such as; enhancing stabilising interactions, modification of residue flexibility and surface charge alteration. It shows that judicious selection of lipase source supplemented by appropriate enzyme stabilisation, can lead to a wide application spectrum for lipases.

CONCLUSION

Organic solvent stable lipases are, and will continue to be, versatile and adaptable biocatalytic workhorses commonly employed for industrial applications in the food, pharmaceutical and green manufacturing industries.

Enhancing the thermostability of Rhizopus oryzae lipase by combined mutation of hot-spots and engineering a disulfide bond

Rhizopus oryzae lipase (ROL) is important because of its extreme sn-1,3-regioselectivity, but it shows poor thermostability, which severely restricts its application. In this work, the thermostability of ROL was greatly enhanced by rational design. First, several sites that may affect the thermostability of ROL were identified by multiple-sequence alignment. The half-lives of mutants V209L and D262G at 55 °C were about 4.38- and 4.2-times those of the wild-type, respectively. Then, a disulfide bond was introduced between positions 190 and 238 based on the prediction of Disulfide by Design 2, which greatly improved the thermostability of the protein. The activity of variant E190C/E238C retained about 58.2% after incubation at 55 °C for 720 min, whereas the half-life of wild type ROL was only about 11.7 min. On the basis of the results obtained by the two methods, we carried out a combined mutation. Quadruple mutant V209L/D262G/E190C/E238C was constructed and the thermostability was improved even further. The half-lives at 55 °C and 65 °C were 102.5- and 20-times those of the wild-type ROL. This improvement in thermostability will give ROL wider industrial applicability, especially in the preparation of structured lipids.

Application of lipase bearing dead mycelia as biocatalyst for octyl-octanoate synthesis

ABSTRACT

The present study scrutinizes lipases of different origins, immobilization methods, carriers, and reaction solvents to accelerate the octyl octanoate synthesis. The acylation reaction parameters including temperature, moisture level, shaking speed and enzyme dose were subsequently investigated and optimized following fully rotatable central composite design. The initial screening revealed that lipases of Rhizopus arrhizus, when applied as a biocatalyst (lipase bearing dead mycelia) furnished the highest acylation activity (147 μM L-1 min-1). Validation of reaction conditions disclosed that 250 I.U. of lipase based biocatalyst when incubated with 850 mM of acylating agent and 750 mM of the substrate at 35 °C, 3% moisture level and 150 RPM shaking speed produced 70% acylation yield with an acylation activity higher than 147 μM L-1 min-1. The observed results certify that lipase bearing dead mycelia of R. arrhizus might be an intelligent biocatalyst to manipulate the yield of acylation reactions encountered in the food industry.

GRAPHICAL ABSTRACT

Evaluation of Strategies to Produce Highly Porous Cross-Linked Aggregates of Porcine Pancreas Lipase with Magnetic Properties

The preparation of highly porous magnetic crosslinked aggregates (pm-CLEA) of porcine pancreas lipase (PPL) is reported. Some strategies to improve the volumetric activity of the immobilized biocatalyst were evaluated, such as treatment of PPL with enzyme surface-modifying agents (polyethyleneimine or dodecyl aldehyde), co-aggregation with protein co-feeders (bovine serum albumin and/or soy protein), use of silica magnetic nanoparticles functionalized with amino groups (SMNPs) as separation aid, and starch as pore-making agent. The combination of enzyme surface modification with dodecyl aldehyde, co-aggregation with SMNPs and soy protein, in the presence of 0.8% starch (followed by hydrolysis of the starch with α-amylase), yielded CLEAs expressing high activity (immobilization yield around 100% and recovered activity around 80%), high effectiveness factor (approximately 65% of the equivalent free enzyme activity) and high stability at 40 °C and pH 8.0, i.e., PPL CLEAs co-aggregated with SMNPs/bovine serum albumin or SMNPs/soy protein retained 80% and 50% activity after 10 h incubation, respectively, while free PPL was fully inactivated after 2 h. Besides, highly porous magnetic CLEAs co-aggregated with soy protein and magnetic nanoparticles (pm-SP-CLEAs) showed good performance and reusability in the hydrolysis of tributyrin for five 4h-batches.

A one-step method for covalent bond immobilization of biomolecules on silica operated in aqueous solution

A simple, one-step method for covalent bond immobilization of biomolecules on silica operated in water is described. In the approach, an NHS-ester linked methallylsilane is utilized as a bifunctional linker to couple the biomolecule to the silica surface. Weak organic acid such as acetic acid activates the silica surface enough to react with bifunctional linker without destroying activity of biomolecule.

Synthesis of a green polyurethane foam from a biopolyol obtained by enzymatic glycerolysis and its use for immobilization of lipase NS-40116

The use of green sources for materials synthesis has gained popularity in recent years. This work investigated the immobilization of lipase NS-40116 (Thermomyces lanuginosus lipase) in polyurethane foam (PUF) using a biopolyol obtained through the enzymatic glycerolysis between castor oil and glycerol, catalyzed by the commercial lipase Novozym 435 for the PUF formation. The reaction was performed to obtain biopolyol resulting in the conversion of 64% in mono- and diacylglycerol, promoting the efficient use of the reaction product as biopolyol to obtain polyurethane foam. The enzymatic derivative with immobilized lipase NS-40116 presented apparent density of 0.19 ± 0.03 g/cm³ and an immobilization yield was 94 ± 4%. Free and immobilized lipase NS-40116 were characterized in different solvents (methanol, ethanol, and propanol), temperatures (20, 40, 60 and 80 °C), pH (3, 5, 7, 9 and 11) and presence of ions Na⁺, Mg⁺⁺, and Ca⁺⁺. The support provided higher stability to the enzyme, mainly when subjected to acid pH (free lipase lost 80% of relative activity after 360 h of contact, when the enzymatic derivative lost around 22%) and high-temperature free lipase lost 50% of relative activity, while the immobilized remained 95%. The enzymatic derivative was also used for esterification reactions and conversions around 66% in fatty acid methyl esters, using abdominal chicken fat as feedstock, were obtained in the first use, maintaining this high conversion until the fourth reuse, proving that the support obtained using environmentally friendly techniques is applicable.

Fluorographene and Graphane as an Excellent Platform for Enzyme Biocatalysis

The application of enzymes is a crucial issue for current biotechnological application in pharmaceutical, as well as food and cosmetic industry. Effective platforms for enzyme immobilization are necessary for their industrial use in various biosynthesis procedures. Such platforms must provide high yield of immobilization and retain high activity at various conditions for their large-scale applications. Graphene derivatives such as hydrogenated graphene (graphane) and fluorographene can be applied for enzyme immobilization with close to 100 % yield that can result to activities of the composites significantly exceeding activity of free enzymes. The hydrophobic properties of graphene stoichiometric derivatives allowed for excellent non-covalent bonding of enzymes and their use in various organic solvents. The immobilized enzymes retain their high activities even at elevated temperatures. These findings show excellent application potential of enzyme biocatalysts immobilized on graphene stoichiometric derivatives.

Enhanced halophilic lipase secretion by Marinobacter litoralis SW-45 and its potential fatty acid esters release

An approach was made to enhance the halophilic lipase secretion by a newly isolated moderate halophilic Marinobacter litoralis SW-45, through the statistical optimization of Plackett-Burman (PB) experimental design and the Face Centered Central Composite Design (FCCCD). Initially, PB statistical design was used to screen the medium components and process parameters, while the One-factor-at-a-time technique was availed to find the optimum level of significant parameters. It was found that MgSO₄  · 7H₂ O, NaCl, agitation speed, FeSO₄  · 7H₂ O, yeast extract and KCl positively influence the halophilic lipase production, whereas temperature, carbon source (maltose), inducer (olive oil), inoculum size, and casein-peptone had a negative effect on enzyme production. The optimum level of halophilic lipase production was obtained at 3.0 g L^-1 maltose, 1% (v/v) olive oil, 30 °C growth temperature and 4% inoculum volume (v/v). Further optimization by FCCCD was revealed 1.7 folds improvement in the halophilic lipase production from 0.603 U ml^-1 to 1.0307 U ml^-1 . Functional and biochemical characterizations displayed that the lipase was significantly active and stable in the pH ranges of 7.0-9.5, temperature (30-50 °C), and NaCl concentration (0-21%). The lipase was maximally active at pH 8.0, 12% (w/v) NaCl, and 50 °C temperature. Besides, M. litoralis SW-45 lipase was found to possess the promising industrial potential to be utilized as a biocatalyst for the esterification.

Novel Sanger's Reagent-like Styrene Polymer for the Immobilization of Burkholderia cepacia Lipase

Sanger's reaction, which was originally developed for amino acid detection, was utilized for enzyme immobilization. The newly synthesized polymer support, which was called polymer NO₂-4-fluorostyrene-divinylbenzene (pNFD), was embedded with a Sanger's reagent-like functional group for immobilizing enzymes covalently under mild reaction conditions. Using Burkholderia cepacia lipase (BCL) as the target enzyme, the immobilization efficiency and activity of pNFD-BCL reached as high as 1.2 mg·g^-1 and 33.21 U·g^-1 (a specific activity of 27 675 U·g^-1), respectively, realizing 90% activity recovery. It also improved the optimal reaction temperature of BCL from 40 to 65 °C, under which its full activity could be retained for 4 h. The new carrier also widened the pH-adaptive range of BCL as 6.5-10.0, allowing the lipase to operate normally in weak acid environment. Reusability of pNFD-BCL was significantly improved as almost no activity and/or enantioselectivity loss was observed in 200 h of triglyceride hydrolysis reaction and 17 batches of ( R, S)-1-phenylethanol resolution reaction.

Investigating Enzyme Activity of Immobilized Candida rugosa Lipase

Candida rugosa lipase is a food-grade enzyme that is extensively utilized in the dairy processing industry for milk fat hydrolysis. The enzyme is mainly employed to modify the fatty acid chain length that results in the enhancement of flavors. The hydrolytic activities of C. rugosa lipase (fungal source) in its free and immobilized forms were investigated at different pH and temperature settings. The main objective of this study was to understand how different support materials (Celite-545, Sephadex G-25, and chitosan) and immobilization techniques alter lipase activity and stability. Our results indicated that hydrolytic activity increased significantly with immobilization on Celite-545. In general, immobilization resulted in considerable improvements in the stability of the enzyme with variations in pH and temperature. Immobilization on Celite-545 led to the highest catalytic efficiency. Remarkable improvements in the recovery and reusability of the immobilized lipases were noted. Comparatively, the acetone immobilization procedure resulted in higher activities than alcohol immobilization. In conclusion, the activity of C. rugosa lipase was enhanced most significantly when immobilized on Celite-545 using acetone as an adsorption solvent.

Sol-Gel Immobilisation of Lipases: Towards Active and Stable Biocatalysts for the Esterification of Valeric Acid

Alkyl esters are high added value products useful in a wide range of industrial sectors. A methodology based on a simple sol-gel approach (biosilicification) is herein proposed to encapsulate enzymes in order to design highly active and stable biocatalysts. Their performance was assessed through the optimization of valeric acid esterification evaluating the effect of different parameters (biocatalyst load, presence of water, reaction temperature and stirring rate) in different alcoholic media, and comparing two different methodologies: conventional heating and microwave irradiation. Ethyl valerate yields were in the 80–85% range under optimum conditions (15 min, 12% m/v biocatalyst, molar ratio 1:2 of valeric acid to alcohol). Comparatively, the biocatalysts were slightly deactivated under microwave irradiation due to enzyme denaturalisation. Biocatalyst reuse was attempted to prove that good reusability of these sol-gel immobilised enzymes could be achieved under conventional heating.