High yield of wax ester synthesized from cetyl alcohol and octanoic acid by lipozyme RMIM and Novozym 435

Intensification of Enzymatic Sorbityl Laurate Production in Dissolved and Neat Systems under Conventional and Microwave Heating

Glycolipids such as sugar alcohol esters have been demonstrated to be relevant for numerous applications across various domains of specialty. The use of organic solvents and, more recently, deep eutectic solvents (DESs) to mediate lipase-supported bioconversions is gaining potential for industrial application. However, many challenges and limitations remain such as extensive time of production and relatively low productivities among others, which must be solved to strengthen such a biocatalytic process in industry. In this context, this study focuses on the intensification of sorbityl laurate production, as a model biocatalyzed reaction using Novozym 435, investigating the relevance of temperature, heating method, and solvent system. By increasing the reaction temperature from 50 to 90 °C, the space-time yield and product yield were considerably enhanced for reactions in DES and the organic solvent 2M2B, irrespective of the heating method (conventional or microwave heating). However, positive effects in 2M2B were more pronounced with conventional heating as 98% conversion yield was reached within 90 min at 90 °C, equating thus to a nearly 4-fold increase in performance yielding 118.0 ± 3.6 g/(L·h) productivity. With DES, the overall yield and space-time yield were lower with both heating methods. However, microwave heating enabled a 2-fold increase in both performance parameters when the reaction temperature was increased from 50 to 90 °C. Compared to conventional heating, a 7-fold increase in space-time yield at 50 °C and a 16-fold increase at 90 °C were achieved in DES by microwave heating. Furthermore, microwave irradiation enabled the usage of a neat, solvent-free system, representing an initial proof of concept with productivities of up to 13.3 ± 2.3 g/(L·h).

Improved antioxidant activity of rutin via lipase-mediated esterification with oleic acid

BACKGROUND

Oxidation is a major problem for oils and fats, which can be mitigated by antioxidants. Rutin has excellent antioxidant activity, but its poor lipid solubility greatly limits its practical application. In this study, an efficient enzymatic synthesis route of lipophilic rutin ester was established using oleic acid as an acyl donor, and the antioxidant potential of rutin oleate was evaluated for the first time by proton (¹ H) nuclear magnetic resonance (NMR) spectroscopy.

RESULTS

The synthesized product was finally identified as rutin oleate by Fourier transform infrared, high-performance liquid chromatography-mass spectrometry, and ¹ H, carbon-13, and DEPT-135 NMR analyses, and the acylation site was the 4‴-OH of the rhamnose group in the rutin molecule. The maximum conversion was over 93% after 48 h of reaction using Novozym 435 as catalyst under the best conditions among these tests. The conversion of rutin ester decreased with the increase of carbon chain length and the number of carbon-carbon double bonds of the fatty acid molecule. Most importantly, rutin oleate exhibited antioxidant capacity comparable to butylated hydroxytoluene and its counterparts (rutin and oleic acid) at low temperatures (60° C), but had a significant advantage at high temperatures (120° C).

CONCLUSION

The antioxidant activity of rutin was significantly enhanced by lipase-mediated esterification with oleic acid. Therefore, rutin oleate could be further developed as a novel antioxidant for use in oil- and fat-based foods. © 2023 Society of Chemical Industry.

The production of wax esters in transgenic plants: towards a sustainable source of bio-lubricants

Wax esters are high-value compounds used as feedstocks for the production of lubricants, pharmaceuticals, and cosmetics. Currently, they are produced mostly from fossil reserves using chemical synthesis, but this cannot meet increasing demand and has a negative environmental impact. Natural wax esters are also obtained from Simmondsia chinensis (jojoba) but comparably in very low amounts and expensively. Therefore, metabolic engineering of plants, especially of the seed storage lipid metabolism of oil crops, represents an attractive strategy for renewable, sustainable, and environmentally friendly production of wax esters tailored to industrial applications. Utilization of wax ester-synthesizing enzymes with defined specificities and modulation of the acyl-CoA pools by various genetic engineering approaches can lead to obtaining wax esters with desired compositions and properties. However, obtaining high amounts of wax esters is still challenging due to their negative impact on seed germination and yield. In this review, we describe recent progress in establishing non-food-plant platforms for wax ester production and discuss their advantages and limitations as well as future prospects.

A review of synthesis of esters with aromatic, emulsifying, and lubricant properties by biotransformation using lipases

The esterification reactions catalyzed by lipases are among the most significant biochemical processes of industrial relevance. The lipases have the function of versatility by catalyzing a diversity of reactions with extreme ease, obtaining quality products with high yield. Therefore, enzyme-catalyzed esterification has gained increasing attention in many applications, due to the importance of derived products. More specifically, lipase-catalyzed esterification reactions have attracted interest in research over the past decade, due to the increased use of organic esters in the chemical and biotechnology industry. These esters can be obtained by three techniques: extraction from natural sources, chemical and enzymatic syntheses. Biotechnological processes have offered several advantages and are shown as a competitive alternative to chemical methods due to high catalytic efficiency, mild operating conditions, and selectivity of natural catalysts. These an industrial point of view, reactions catalyzed by enzymes are the most economical approach to achieve green products with no toxicity and no harm to human health. Thus, this review presents a descriptive evaluation of the trends and perspectives applied to enzymatic esterification, mainly for the synthesis of esters with different properties, such as aromatics, emulsifiers, and lubricants using the esterification process. An emphasis is given to essential factors, which affect the lipase-catalyzed esterification reaction. In which, the parameters dependent on the lipase source, a form of the biocatalyst (free or immobilized), the polarity of the reaction medium, the molar ratio between alcohol and acid, among other variables, are also discussed. This article is protected by copyright. All rights reserved.

Selective production of retinol by engineered Saccharomyces cerevisiae through the expression of retinol dehydrogenase

Retinol is a fat-soluble vitamin A that is widely used in the food and pharmaceutical industries. Currently, retinol is commercially produced by chemical synthesis. Microbial production of retinol has been alternatively explored but restricted to a mixture of retinoids including retinol, retinal, and retinoic acid. Thus, we introduced heterologous retinol dehydrogenase into retinoids mixture-producing Saccharomyces cerevisiae for the selective production of retinol using xylose. Expression of human RDH10 and Escherichia coli ybbO led to increase in retinol production, but retinal remained as a major product. In contrast, S. cerevisiae harboring human RDH12 produced retinol selectively with negligible production of retinal. The resulting strain (SR8A-RDH12) produced retinol only. However, more glycerol was accumulated due to intracellular redox imbalance. Therefore, Lactococcus lactis noxE coding for H₂ O-forming NADH oxidase was additionally introduced to resolve the redox imbalance. The resulting strain produced 52% less glycerol and more retinol with a 30% higher yield than a parental strain. As the produced retinol was not stable, we examined culture and storage conditions including temperature, light, and antioxidants for the optimal production of retinol. In conclusion, we achieved selective production of retinol efficiently from xylose by introducing human RDH12 and NADH oxidase into S. cerevisiae.

Modification of Silica Xerogels with Polydopamine for Lipase B from Candida antarctica Immobilization

Silica xerogels have been proposed as a potential support to immobilize enzymes. Improving xerogels’ interactions with such enzymes and their mechanical strengths is critical to their practical applications. Herein, based on the mussel-inspired chemistry, we demonstrated a simple and highly effective strategy for stabilizing enzymes embedded inside silica xerogels by a polydopamine (PDA) coating through in-situ polymerization. The modified silica xerogels were characterized by scanning and transmission electron microscopy, Fourier tranform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and pore structure analyses. When the PDA-modified silica xerogels were used to immobilize enzymes of Candida antarctica lipase B (CALB), they exhibited a high loading ability of 45.6 mg/gsupport, which was higher than that of immobilized CALB in silica xerogels (28.5 mg/gsupport). The immobilized CALB of the PDA-modified silica xerogels retained 71.4% of their initial activities after 90 days of storage, whereas the free CALB retained only 30.2%. Moreover, compared with the immobilization of enzymes in silica xerogels, the mechanical properties, thermal stability and reusability of enzymes immobilized in PDA-modified silica xerogels were also improved significantly. These advantages indicate that the new hybrid material can be used as a low-cost and effective immobilized-enzyme support.

Candida rugosa lipase immobilized on hydrophobic support Accurel MP 1000 in the synthesis of emollient esters

OBJECTIVES

To immobilize Candida rugosa lipase in Accurel MP 1000 (CRL-AMP) by physical adsorption in organic medium and apply in the synthesis of wax esters dodecanoyl octadecanoate 1 and hexadecanoyl octadecanoate 2 in a heptane medium, as well as evaluating the stability and recyclability of CRL-AMP in six reaction cycles.

RESULTS

The specific activity (A_sp) for CRL-AMP was 200 ± 20 U mg^-1. Its catalytic activity was 1300 ± 100 U g^-1. CRL-AMP was used in the synthesis of esters in heptane medium with a 1:1 acid:alcohol molar ratio at 45 °C and 200 rpm. In synthesis 1, conversion was 62.5 ± 3.9% in 30 min at 10% m v^-1 and 56.9 ± 2.8% in 54 min at 5% m v^-1; while in synthesis 2, conversion was 79.0 ± 3.9% in 24 min at 10% m v^-1, and 46.0 ± 2.4% in 54 min at 5% m v^-1. Reuse tests after six consecutive cycles of reaction showed that the biocatalyst retained approximately 50% of its original activity for both reaction systems.

CONCLUSIONS

CRL-AMP showed a high potential in the production of wax esters, since it started from low enzymatic load and high specific activities and conversions were obtained, in addition to allowing an increase in stability and recyclability of the prepared biocatalyst.

Lipases of germinating jojoba seeds efficiently hydrolyze triacylglycerols and wax esters and display wax ester-synthesizing activity

BACKGROUND

Simmondsia chinensis (jojoba) is the only plant known to store wax esters instead of triacylglycerols in its seeds. Wax esters are composed of very-long-chain monounsaturated fatty acids and fatty alcohols and constitute up to 60% of the jojoba seed weight. During jojoba germination, the first step of wax ester mobilization is catalyzed by lipases. To date, none of the jojoba lipase-encoding genes have been cloned and characterized. In this study, we monitored mobilization of storage reserves during germination of jojoba seeds and performed detailed characterization of the jojoba lipases using microsomal fractions isolated from germinating seeds.

RESULTS

During 26 days of germination, we observed a 60-70% decrease in wax ester content in the seeds, which was accompanied by the reduction of oleosin amounts and increase in glucose content. The activity of jojoba lipases in the seed microsomal fractions increased in the first 50 days of germination. The enzymes showed higher activity towards triacylglycerols than towards wax esters. The maximum lipase activity was observed at 60 °C and pH around 7 for triacylglycerols and 6.5-8 for wax esters. The enzyme efficiently hydrolyzed various wax esters containing saturated and unsaturated acyl and alcohol moieties. We also demonstrated that jojoba lipases possess wax ester-synthesizing activity when free fatty alcohols and different acyl donors, including triacylglycerols and free fatty acids, are used as substrates. For esterification reactions, the enzyme utilized both saturated and unsaturated fatty alcohols, with the preference towards long chain and very long chain compounds.

CONCLUSIONS

In in vitro assays, jojoba lipases catalyzed hydrolysis of triacylglycerols and different wax esters in a broad range of temperatures. In addition, the enzymes had the ability to synthesize wax esters in the backward reaction. Our data suggest that jojoba lipases may be more similar to other plant lipases than previously assumed.

Biocatalytic Process Optimization

Biocatalysis refers to the use of microorganisms and enzymes in chemical reactions, has become increasingly popular and is frequently used in industrial applications due to the high efficiency and selectivity of biocatalysts [...]

Continuous Production of 2-Phenylethyl Acetate in a Solvent-Free System Using a Packed-Bed Reactor with Novozym® 435

2-Phenylethyl acetate (2-PEAc), a highly valued natural volatile ester, with a rose-like odor, is widely added in cosmetics, soaps, foods, and drinks to strengthen scent or flavour. Nowadays, 2-PEAc are commonly produced by chemical synthesis or extraction. Alternatively, biocatalysis is a potential method to replace chemical synthesis or extraction for the production of natural flavour. Continuous synthesis of 2-PEAc in a solvent-free system using a packed bed bioreactor through immobilized lipase-catalyzed transesterification of ethyl acetate (EA) with 2-phenethyl alcohol was studied. A Box–Behnken experimental design with three-level-three-factor, including 2-phenethyl alcohol (2-PE) concentration (100–500 mM), flow rate (1–5 mL min−1) and reaction temperature (45–65 °C), was selected to investigate their influence on the molar conversion of 2-PEAc. Then, response surface methodology and ridge max analysis were used to discuss in detail the optimal reaction conditions for the synthesis of 2-PEAc. The results indicated both 2-PE concentration and flow rate are significant factors in the molar conversion of 2-PEAc. Based on the ridge max analysis, the maximum molar conversion was 99.01 ± 0.09% under optimal conditions at a 2-PE concentration of 62.07 mM, a flow rate of 2.75 mL min−1, and a temperature of 54.03 °C, respectively. The continuous packed bed bioreactor showed good stability for 2-PEAc production, enabling operation for at least 72 h without a significant decrease of conversion.

Enhanced Ricinoleic Acid Preparation Using Lipozyme TLIM as a Novel Biocatalyst: Optimized by Response Surface Methodology

Ricinoleic acid (RA) is an important raw material for plasticizers, emulsifiers, and nanomaterials. In this work, a green and efficient method was developed for RA production. Results showed that Lipozyme TLIM can be used as a novel biocatalyst to catalyze the hydrolysis of castor oil (CO) for RA preparation. Response surface methodology (RSM) was used to evaluate and optimize the effects of reaction variables on the hydrolysis of CO. Reaction conditions were optimized as follows: 41.3 °C, enzyme load 8.9%, 39.2 h, and 40:1 molar ratio of water to oil. Under these optimized reaction variables, the maximum hydrolysis ratio of CO (96.2 ± 1.5%) was obtained. The effect of hydrolysis variables on the reaction was as follows: enzyme load > hydrolysis time > temperature. In conclusion, this is a green, simple, and efficient method for RA preparation and can provide a good alternative method for RA industrial production.

Structural and Biochemical Studies of a Biocatalyst for the Enzymatic Production of Wax Esters

Wax esters are high-value products whose enzymatic synthesis is of increasing biotechnological interest. The fabrication of cell factories that mass-produce wax esters may provide a facile route towards a sustainable, and environment-friendly approach to a large-scale process for this commodity chemical. An expedient route for wax-ester biocatalysis may be facilitated by the action of enzymes termed wax ester synthases/diacylglycerol acyltransferases (WS/DGAT), which produce wax esters using fatty acids and alcohols as a precursor. In this work, we report the structure for a member of the WS/DGAT superfamily. The structural data in conjunction with bioinformatics and mutational analyses allowed us to identify the substrate binding pockets, and residues that may be important for catalysis. Using this information as a guide, we generated a mutant with preference towards shorter acyl-substrates. This study demonstrates the efficacy of a structure-guided engineering effort towards a WS/DGAT variant with preference towards wax esters of desired lengths.

Kinetics and Optimization of Lipophilic Kojic Acid Derivative Synthesis in Polar Aprotic Solvent Using Lipozyme RMIM and Its Rheological Study

The synthesis of kojic acid derivative (KAD) from kojic and palmitic acid (C16:0) in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM), was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT) experiments, a high reaction rate (30.6 × 10⁻³ M·min⁻¹) of KAD synthesis was recorded using acetone, enzyme loading of 1.25% (w/v), reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM) whereby the optimized molar ratio (fatty acid: kojic acid), enzyme loading, reaction temperature and reaction time were 6.74, 1.97% (w/v), 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%). This condition was reevaluated in a 0.5 L stirred tank reactor (STR) where the agitation effects of two impellers; Rushton turbine (RT) and pitch-blade turbine (PBT), were investigated. In the STR, a very high yield of KAD synthesis (84.12%) was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation.

Lipase catalysed synthesis of cetyl oleate using ultrasound: Optimisation and kinetic studies

The current paper exemplifies the application of ultrasound technology to enzymatic synthesis of a cosmetic emollient ester, cetyl oleate. Fermase CALB™10000, a commercial Candida antarctica lipase B was used as a catalyst to accomplish the ultrasound supported synthesis. Multiple process parameters like reaction time, temperature, enzyme dose, alcohol to acid molar ratio, ultrasound power, frequency and speed of agitation were optimised. Maximum conversion of ∼95.96% was discerned at optimum conditions, i.e., 60°C temperature, 5% enzyme dose, 2:1 alcohol:acid ratio, 60 W ultrasound power, 25 kHz ultrasound frequency, 80% duty cycle and 80 rpm speed of agitation after purification steps. It was observed that the reaction reached equilibrium in a short duration of 30 min under the optimised conditions. This was considerably lesser than the time required for attaining equilibrium in conventional mechanical stirring method which was over 2h. Bisubstrate kinetic models like random bi-bi, ping pong bi-bi and ordered bi-bi were applied to the experimental data to determine initial rates and other kinetic parameters. Ordered bi-bi model showed the best fit with kinetic parameters, Vmax=0.029 M/min/gcatalyst, KA=0.00001 M, KB=4.8002 M, KiA=0.00014 M, KiB=3.7914 M & SSE=0.00022 for enzymatic cetyl oleate synthesis under ultrasound irradiation with inhibition by both acid and alcohol at high concentrations.