Efficient preparation of (R)-alpha-monobenzoyl glycerol by lipase catalyzed asymmetric esterification: optimization and operation in packed bed reactor

An overview on the conversion of glycerol to value-added industrial products via chemical and biochemical routes

Glycerol is a common by-product of industrial biodiesel syntheses. Due to its properties, availability, and versatility, residual glycerol can be used as a raw material in the production of high value-added industrial inputs and outputs. In particular, products like hydrogen, propylene glycol, acrolein, epichlorohydrin, dioxalane and dioxane, glycerol carbonate, n-butanol, citric acid, ethanol, butanol, propionic acid, (mono-, di-, and triacylglycerols), cynamoil esters, glycerol acetate, benzoic acid, and other applications. In this context, the present study presents a critical evaluation of the innovative technologies based on the use of residual glycerol in different industries, including the pharmaceutical, textile, food, cosmetic, and energy sectors. Chemical and biochemical catalysts in the transformation of residual glycerol are explored, along with the factors to be considered regarding the choice of catalyst route used in the conversion process, aiming at improving the production of these industrial products.

From batch to fed-batch and to continuous packed-bed reactors: Lipase-catalyzed esterifications in low viscous deep-eutectic-solvents with buffer as cosolvent

This work explores for the first time the use of Deep Eutectic Solvents (DES) with phosphate buffer 100 mM pH 7 as cosolvent (10% v/v) in biocatalytic reactions in fed-batch and packed-bed bioreactors. The lipase-catalyzed esterification of glycerol and benzoic acid is studied, as it involves two substrates with different polarities (for which DES are needed). In the fed-batch bioreactor, the highest conversion (90%) was obtained at a substrate flow rate of 0.01 mL/min. The fed-batch operation increased the conversion by 59% compared to the batch mode. Regarding productivity, semi-continuous and continuous bioreactors showed analogous results. Upon recirculation of the reaction media in the continuous bioreactor, a conversion of 67% was achieved in 7 cycles of operation. The stability of the biocatalyst in the packed-bed bioreactor decreased only 2% in 10 days, demonstrating the attractiveness that low viscous DES-water mixtures with continuous processes may have.

Continuous Production of Ursodeoxycholic Acid by Using Two Cascade Reactors with Co-immobilized Enzymes

Ursodeoxycholic acid (UDCA) is an effective drug for the treatment of hepatitis. In this study, 7α-hydroxysteroid dehydrogenase (7α-HSDH) and lactate dehydrogenase (LDH), as well as 7β-hydroxysteroid dehydrogenase (7β-HSDH) and glucose dehydrogenase (GDH), were co-immobilized onto an epoxy-functionalized resin (ES-103) to catalyze the synthesis of UDCA from chenodeoxycholic acid (CDCA). Through optimizing the immobilization pH, time, and loading ratio of enzymes to resin, the specific activities of immobilized LDH-7αHSDH@ES-103 and 7βHSDH-GDH@ES-103 were 43.2 and 25.8 U g^-1 , respectively, which were 12- and 516-fold higher than that under the initial immobilization conditions. Continuous production of UDCA from CDCA was subsequently achieved by using immobilized LDH-7αHSDH@ES-103 and 7βHSDH-GDH@ES-103 in two serial packed-bed reactors. The yield of UDCA reached nearly 100 % and lasted for at least 12 h in the packed-bed reactors, which was superior to that of the batchwise reaction. This efficient continuous approach developed herein might provide a feasible route for large-scale biotransformation of CDCA into UDCA.

Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR) studies

Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

The efficient desymmetrization of glycerol using scaffolding catalysis

Glycerol is an ideal building block for the synthesis of complex molecules, because it is inexpensive and highly functionalized. We report the desymmetrization of glycerol through silyl transfer, using a chiral organic catalyst in high yield and enantioselectivity.

A review on the effects of supercritical carbon dioxide on enzyme activity

Different types of enzymes such as lipases, several phosphatases, dehydrogenases, oxidases, amylases and others are well suited for the reactions in SC-CO₂. The stability and the activity of enzymes exposed to carbon dioxide under high pressure depend on enzyme species, water content in the solution and on the pressure and temperature of the reaction system. The three-dimensional structure of enzymes may be significantly altered under extreme conditions, causing their denaturation and consequent loss of activity. If the conditions are less adverse, the protein structure may be largely retained. Minor structural changes may induce an alternative active protein state with altered enzyme activity, specificity and stability.

Production, purification, characterization, and applications of lipases

Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of esters formed from glycerol and long-chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. The many applications of lipases include speciality organic syntheses, hydrolysis of fats and oils, modification of fats, flavor enhancement in food processing, resolution of racemic mixtures, and chemical analyses. This article discusses the production, recovery, and use of microbial lipases. Issues of enzyme kinetics, thermostability, and bioactivity are addressed. Production of recombinant lipases is detailed. Immobilized preparations of lipases are discussed. In view of the increasing understanding of lipases and their many applications in high-value syntheses and as bulk enzymes, these enzymes are having an increasing impact on bioprocessing.