Thermo-kinetics of lipase-catalyzed synthesis of 6-O-glucosyldecanoate

Post-Synthetic Enzymatic and Chemical Modifications for Novel Sustainable Polyesters

Because of their biodegradability, compostability, compatibility and flexible structures, biodegradable polymers such as polyhydroxyalkanoates (PHA) are an important class of biopolymers with various industrial and biological uses. PHAs are thermoplastic polyesters with a limited processability due to their low heat resistance. Furthermore, due to their high crystallinity, some PHAs are stiff and brittle. These features result sometimes in very poor mechanical characteristics with low extension at break values which limit the application range of some natural PHAs. Several in vivo approaches for PHA copolymer modifications range from polymer production to enhance PHA-based material performance after synthesis. The methods for enzymatic and chemical polymer modifications are aiming at modifying the structures of the polyesters and thereby their characteristics while retaining the biodegradability. This survey illustrates the efficient use of enzymes and chemicals in post-synthetic PHA modifications, offering insights on these green techniques for modifying and improving polymer performance. Important studies in this sector will be reviewed, as well as chances and obstacles for their stability and hyper-production.

An Integrated Enzymatic Approach to Produce Pentyl Xylosides and Glucose/Xylose Laurate Esters From Wheat Bran

Alkyl glycosides and sugars esters are non-ionic surfactants of interest for various applications (cosmetics, food, detergency,…). In the present study, xylans and cellulose from wheat bran were enzymatically converted into pentyl xylosides and glucose and xylose laurate monoesters. Transglycosylation reaction catalyzed by the commercial enzymatic cocktail Cellic Ctec2 in the presence of pentanol led to the synthesis of pentyl β-D-xylosides from DP1 to 3 with an overall yield of 520 mg/g of xylans present in wheat bran. Enzymatic hydrolysis of wheat bran with Cellic Ctec2 and subsequent acylation of the recovered D-glucose and D-xylose catalyzed by the commercial lipase N435 in the presence of lauric acid or methyl laurate produced one D-glucose laurate monoester and one D-xylose laurate monoester. An integrated approach combining transglycosylation and (trans)esterification reactions was successfully developed to produce both pentyl xylosides and D-glucose and D-xylose laurate esters from the same batch of wheat bran.

Solvent-free esterifications mediated by immobilized lipases: a review from thermodynamic and kinetic perspectives

Esters are a highly relevant class of compounds in the industrial context, and biocatalysis applied to ester syntheses is already a reality for some chemical companies.

Investigation of effect of ultrasound on immobilized C. rugosa lipase: Synthesis of biomass based furfuryl derivative and green metrics evaluation study

The present work deals with the synthesis of lab-made carboxymethyl cellulose (CMC) and chitosan (CHI) based co-polymer cross-linked with glutaraldehyde (GLU) which is used as immobilization matrix for the immobilization of Candida rugosa (CRL) lipase (CMC:CHI:GLU:CRL). This immobilized biocatalyst was subjected to characterization such as lipase-activity, kinetic-parameters, water-content, surface-texture, stability and half-life time etc. Effect of various ultrasound parameters (power, frequency, duty cycle, exposure time) on lipase activity is also tested which indicated that, developed biocatalyst has significant activity-stability and half-life-time in ultrasonicated medium. Further, this biocatalyst was applied to synthesize biomass-derived furfuryl derivative which offering excellent conversion of 99 % of bio-based furfuryl ester. The synthetic protocol is optimized in detail (with twelve reaction parameters) under ultrasonicated medium. Recyclability study offered 68 % conversion of the furfuryl ester after sixth reuse. Moreover, the developed protocol is well extended to synthesize various commercially important compounds. Besides this, we investigated thermodynamic parameters (ΔG*, ΔH*, ΔS*) which demonstrating more feasibility of biocatalytic synthesis in ultrasonicated medium than conventional medium. Finally, green metrics evaluation parameters (E-factor, carbon-efficiency and mass-intensity) are studied which indicating efficient synergetic role of immobilized CMC:CHI:GLU:CRL lipase biocatalysis and ultrasonication in green and sustainable synthesis.

Synthesis of lutein esters using a novel biocatalyst of Candida antarctica lipase B covalently immobilized on functionalized graphitic carbon nitride nanosheets

Lutein scavenges free radicals and inhibits vision damage caused by photo oxidation, while decomposing easily with light and heat. Its stability and bioavailability can be tremendously improved by lutein ester synthesis. However, green and efficient esterification preparation methods are urgently needed. In this study, which used functionalized graphitic carbon nitride nanosheets (g-C₃N₄-Ns) as the immobilized carrier, a novel biocatalyst was designed and prepared to accommodate Candida antarctica lipase B (CALB), considerably enhancing the performance. It was characterized by TEM, XRD, FTIR, XPS, TGA, and BET to demonstrate successful preparation and then applied to catalyze esterification between lutein and succinate anhydride in dimethyl formamide (DMF) solvent resulting in a conversion rate up to 92% at 50 °C in 60 h, 34% more than free CALB under the same conditions. We believe this is the highest esterification rate in lutein esters synthesis and it has great potential to facilitate eco-friendly and efficient preparation.

Microbial biosynthesis and in vivo depolymerization of intracellular medium-chain-length poly-3-hydroxyalkanoates as potential route to platform chemicals

Biosynthesis and in vivo depolymerization of intracellular medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 grown on lauric acid were studied. Highest mcl-PHA fraction (>50 % of total biomass) and cell concentration (8 g L^-1 ) were obtained at carbon-to-nitrogen (C/N) ratio 20, starting cell concentration 1 g L^-1 , and 48 H fermentation. The mcl-PHA comprised of 3-hydroxyhexanoate (C₆ ), 3-hydroxyoctanote (C₈ ), 3-hydroxydecanoate (C₁₀ ), and 3-hydroxydodecanoate (C₁₂ ) monomers. In vivo action was studied in a mineral liquid medium without carbon source, and in different buffer solutions with varied pH, molarity, ionic strength, and temperature. The monomer liberation rate reflected the mol percentage distribution of the initial polymer subunit composition. Rate and percentage of in vivo depolymerization were highest in 0.2 M Tris-HCl buffer (pH 9, strength = 0.2 M, 30 °C) at 0.21 g L^-1  H^-1 and 98.6 ± 1.3 wt%, respectively. There is a congruity vis-à-vis to specific buffer type, molarity, pH, ionic strength, and temperature values for superior in vivo depolymerization activities. Direct products from in vivo depolymerization matched the individual monomeric composition of native mcl-PHA. It points to exo-type reaction for the in vivo process, and potential biological route to chiral molecules.

d-Xylose and l-arabinose laurate esters: Enzymatic synthesis, characterization and physico-chemical properties

Efficient enzymatic synthesis of d-xylose and l-arabinose lauryl mono- and diesters has been achieved by transesterification reactions catalysed by immobilized Candida antarctica lipase B as biocatalyst, in organic medium in the presence of d-xylose or l-arabinose and vinyllaurate at 50 °C. In case of l-arabinose, one monoester and one diester were obtained in a 57% overall yield. A more complex mixture was produced for d-xylose as two monoesters and two diesters were synthesized in a 74.9% global yield. The structures of all these pentose laurate esters was solved. Results demonstrated that the esterification first occurred regioselectively onto the primary hydroxyl groups. Pentose laurate esters exhibited interesting features such as low critical aggregation concentrations values all inferior to 25 μM. Our study demonstrates that the enzymatic production of l-arabinose and d-xylose-based esters represents an interesting approach for the production of green surfactants from lignocellulosic biomass-derived pentoses.

Biosynthesis of Neokestose Laurate Catalyzed by Candida antarctica Lipase B and Its Antimicrobial Activity against Food Pathogenic and Spoilage Bacteria

To increase the functionality and broaden the potential application of neokestose, neokestose laurate was biosynthesized using Candida antarctica lipase B as biocatalyst, for which a mixture of 20% DMSO in 2-methyl-2-butanol (v/v) was chosen as the reaction medium. The optimum conditions for biosynthesis were as follows: a molar ratio of vinyl laurate to neokestose of 12, a temperature of 50 °C, molecular sieves of 100 g/L, and enzyme loading of 10 g/L. Under the optimal conditions, the conversion rate was achieved over 80%. The synthesized chemical 6'-O-lauroylneokestose confirmed by nuclear magnetic resonance (NMR) exhibited good emulsification with critical micelle concentration (CMC) of 352 μM and broad antibacterial activity against Gram-positive bacteria such as Staphylococcus aureus, Listeria monocytogenes, Streptococcus mutans, Bacillus subtilis, and Bacillus cereus. Conclusively, 6'-O-lauroylneokestose was evidenced to be a dual-functional agent with emulsification and antibacterial activity, showing promising application potential in the food industry.

Carbon nanotube filled with magnetic iron oxide and modified with polyamidoamine dendrimers for immobilizing lipase toward application in biodiesel production

Superparamagnetic multi-walled carbon nanotubes (mMWCNTs) were prepared by filling multi-walled carbon nanotubes (MWCNTs) with iron oxide, and further modified by linking polyamidoamine (PAMAM) dendrimers (mMWCNTs-PAMAM) on the surface. Then, mMWCNTs-PAMAM was employed as the carrier and successfully immobilized Burkholderia cepacia lipase (BCL) via a covalent method (BCL-mMWCNTs-G3). The maximum activity recovery of the immobilized lipase was 1,716% and the specific activity increased to 77,460 U/g-protein, 17-fold higher than that of the free enzyme. The immobilized lipase displayed significantly enhanced thermostability and pH-resistance, and could efficiently catalyze transesterification to produce biodiesel at a conversion rate of 92.8%. Moreover, it possessed better recycling performance. After 20 cycles of repeated used, it still retained ca. 90% of its original activity, since the carbon nanotube-enzyme conjugates could be easily separated from the reaction mixture by using a magnet. This study provides a new perspective for biotechnological applications by adding a magnetic property to the unique intrinsic properties of nanotubes.

Thermomyces lanuginosus lipase-catalyzed synthesis of natural flavor esters in a continuous flow microreactor

Enzymatic catalysis is considered to be among the most environmental friendly processes for the synthesis of fine chemicals. In this study, lipase from Thermomyces lanuginosus (Lecitase Ultra™) was used to catalyze the synthesis of flavor esters, i.e., methyl butanoate and methyl benzoate by esterification of the acids with methanol in a microfluidic system. Maximum reaction rates of 195 and 115 mM min⁻¹ corresponding to catalytic efficiencies (k_cat/K_M) of 0.30 and 0.24 min⁻¹ mM⁻¹ as well as yield conversion of 54 and 41 % were observed in methyl butanoate and methyl benzoate synthesis, respectively. Catalytic turnover (k_cat) was higher for methyl butanoate synthesis. Rate of synthesis and yield decreased with increasing flow rates. For both esters, increase in microfluidic flow rate resulted in increased advective transport over molecular diffusion and reaction rate, thus lower conversion. In microfluidic synthesis using T. lanuginosus lipase, the following reaction conditions were 40 °C, flow rate 0.1 mL min⁻¹, and 123 U g⁻¹ enzyme loading found to be the optimum operating limits. The work demonstrated the application of enzyme(s) in a microreactor system for the synthesis of industrially important esters.

Biodiesel production from microalgae oil catalyzed by a recombinant lipase

A recombinant Rhizomucor miehei lipase was constructed and expressed in Pichia pastoris. The target enzyme was termed Lipase GH2 and it can be used as a free enzyme for catalytic conversion of microalgae oil mixed with methanol or ethanol for biodiesel production in an n-hexane solvent system. Conversion rates of two major types of biodiesel, fatty acid methyl ester (FAME) and fatty acid ethyl ester (FAEE), reached maximal values (>90%) after 24h. The process of FAME production is generally more simple and economical than that of FAEE production, even though the two processes show similar conversion rates. In spite of the damaging effect of ethanol on enzyme activity, we successfully obtained ethyl ester by the enzymatic method. Our findings indicate that Lipase GH2 is a useful catalyst for conversion of microalgae oil to FAME or FAEE, and this system provides efficiency and reduced costs in biodiesel production.

Synthesis of lipase nano-bio-conjugates as an efficient biocatalyst: characterization and activity–stability studies with potential biocatalytic applications

Synthesis of lipase nano-bio-conjugate and their detail biocatalytic application studies.

Lipase catalyzed ultrasonic synthesis of poly-4-hydroxybutyrate-co-6-hydroxyhexanoate

Four different lipases were compared for ultrasound-mediated synthesis of the biodegradable copolymer poly-4-hydroxybutyrate-co-6-hydroxyhexanoate. The copolymerization was carried out in chloroform. Of the enzymes tested, Novozym 435 exhibited the highest copolymerization rate, in fact the reaction rate was observed to increase with about 26-fold from 30 to 50°C (7.9×10(-3)Ms(-1)), sonic power intensity of 2.6×10(3)Wm(-2) and dissipated energy of 130.4Jml(-1). Copolymerization rates with the Candida antarctica lipase A, Candida rugosa lipase, and Lecitase Ultra™ were lower at 2.4×10(-4), 1.3×10(-4) and 3.5×10(-4)Ms(-1), respectively. The catalytic efficiency depended on the enzyme. The efficiency ranged from 4.15×10(-3)s(-1)M(-1) for Novozym 435-1.48×10(-3)s(-1)M(-1) for C. rugosa lipase. Depending on the enzyme and sonication intensity, the monomer conversion ranged from 8.2% to 48.5%. The sonication power, time and temperature were found to affect the rate of copolymerization. Increasing sonication power intensity from 1.9×10(3) to 4.5×10(3)Wm(-2) resulted in an increased in acoustic pressure (P(a)) from 3.7×10(8) to 5.7×10(8)Nm(-2) almost 2.4-3.7 times greater than the acoustic pressure (1.5×10(8)Nm(-2)) that is required to cause cavitation in water. A corresponding acoustic particle acceleration (a) of 9.6×10(3)-1.5×10(4)ms(-2) was calculated i.e. approximately 984-1500 times greater than under the action of gravity.

Regioselective enzymatic undecylenoylation of 8-chloroadenosine and its analogs with biomass-based 2-methyltetrahydrofuran as solvent

2-Methyltetrahydrofuran (MeTHF), a biomass-derived compound, is a promising medium for biocatalysis and organometallic reactions. The regioselective acylation of 8-chloroadenosine (8-Cl-Ado) and its analogs was carried out in MeTHF with immobilized Penicillium expansum lipase. The lipase displayed more than twofold higher catalytic activity and much better thermostability in MeTHF than in other organic solvents and co-solvent systems. The optimum reaction medium, enzyme dosage, molar ratio of viny ester to nucleoside and reaction temperature for the enzymatic acylation of 8-Cl-Ado were MeTHF, 25 U/mL, 7.5 and 35 °C, respectively, under which the desirable 5'-O-undecylenoyl-8-Cl-Ado was obtained with a yield of 95% and a regioselectivity of >99% in 3 h. In addition, the lipase catalyzed regioselective undecylenoylation of other purine nucleosides, producing 5'-undecylenic acid esters with moderate to high yields (63-94%) and excellent 5'-regioselectivities (94->99%). Use of biomass-derived solvents might open up novel opportunities for sustainable and greener biocatalytic processes.

Lipase-mediated synthesis of water-soluble plant stanol derivatives in tert-butanol

The effects of solvents with different log P values, and of lipases on the synthesis of water-soluble plant stanol derivatives were investigated. Results showed that conversion in solvents with log P<0.37 was mainly controlled by the hydrophobicity of the solvent and subsequent complete or partial deactivation of the enzyme. The solubility of substrate was the leading factor for the conversion in solvents with log P>0.37. Lipozyme RM IM and tert-butanol was the most suitable biocatalyst and solvent, respectively. The highest yield (>51%) of plant stanyl sorbitol succinate was obtained under the selected conditions: 50 μmol/mL plant stanyl hemisuccinate, 1:3 molar ratio of plant stanyl hemisuccinate to d-sorbitol, 80 mg/mL 3 Å molecular sieves and 100mg/mL Lipozyme RM IM in tert-butanol, 150 r/min and 55 °C. Fourier transform infrared spectroscopy, mass spectroscopy and nuclear magnetic resonance spectroscopy were adopted to determine the structure of product, suggesting that water-soluble plant stanol derivatives were successfully synthesized.