Search

A novel approach to ultrasound-assisted Pickering interfacial biocatalysis (PIB) has been proposed and implemented for the efficient enzymatic transesterification production of vitamin A fatty acid esters. This is the first instance of exploiting the synergistic effect of ultrasound and the bifunctional modification of enzyme supports to accelerate biocatalytic performance in PIB systems. The optimal conditions were determined to be ultrasound power of 70 W, on/off time of 5 s/5 s, substrate molar ratio of 1:1, enzyme addition of 2 %, and a volume ratio of n-hexane to PBS of 3:1, a temperature of 40 °C, and a time of 30 min. The application of ultrasound technology not only improved lipase activity but also allowed for a reduction in emulsion droplet size to enhance interfacial mass transfer.Bifunctional modification of silica-based supports enhanced stability of immobilized enzymes by increasing hydrogen bonding while maintaining the active interface microenvironment. Compared with a non-ultrasound-assisted PIB system stabilized by mono-modified immobilized enzyme particles, the catalytic efficacy (CE) of the novel system reached 8.18 mmol g -1 min -1 , which was enhanced by 3.33-fold, while the interfacial area was found to have increased by 17.5-fold. The results facilitated the conversion of vitamin A palmitate (VAP), vitamin A oleate (VAO), vitamin A linoleate (VAL), and vitamin A linolenate (VALn), with conversion rates of approximately 98.2 %, 97.4 %, 96.1 %, and 94.7 %, respectively. This represents the most efficient example that has been reported to our knowledge. Furthermore, the system demonstrated improved reusability, with a conversion rate of 62.1 % maintained even after 10 cycles. The findings presented in this paper provide valuable insights into an efficient and conveniently promising protocol for the development of PIB systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

In this study, a continuous-flow bioreactor packed with well-organized lipase microarrays was developed for the sustainable synthesis of functional lipid-phytosterol esters (PEs). Hollow mesoporous silicon spheres with a suitable pore size were prepared for lipase immobilization, and the hydrophobic modification endowed the lipase with excellent catalytic activity and stability. The results showed that the condensely packed lipase microarrays offered large specific surface areas and guaranteed the thorough interaction between the lipase and substrates in the continuous-flow bioreactor. Meanwhile, the substrate could pass through the reactor at 1 mL/min with a high conversion of 93.6% due to the hollow structure of the packing spheres. Moreover, the reactors were able to produce 1564 g PEs/g catalyst in a continuous 30-day processing period, which set the highest records for PEs synthesis. This sustainable and highly-converting flow system provided a feasible path for scale-up production of PEs in the food processing area., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this study, a series of functional oils rich in feruloylated structured lipids (FSLs) was prepared by enzymatic transesterification of ethyl ferulate (EF) with triglycerides under ultrasound pretreatment. A conversion of more than 92.7% and controllable FSLs (3.1%-26.3%) can be obtained under the following conditions: 16% enzyme, substrate ratio 1:5 (oil/EF, mol/mol), 85 °C, ultrasound 1 h, pulse mode 3 s/3s (working/waiting), and 17.0 W/mL. Compared to conventional mechanical stirring, the activation energy decreased from 50.0 kJ/mol to 40.7 kJ/mol. The apparent kinetic constant increased by more than 13 times, and the time required for the maximum conversion reduced sharply from 20-60 h to 4-6h, which was the fastest rate for enzymatic synthesis of FSLs. The antioxidant activities of the functional oil significantly increased 1.0- to 8.1-fold more than that of the raw oil. The functional oil could be widely applied in various fields of functional foods., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Monoglyceryl phenolic acids (MPAs) were known as the natural hydrophilic antioxidants which could be used in different fields such as food, pharmaceutical, cosmetic etc. A novel enzymatic route of MPAs synthesis by the alcoholysis of phenolic acid ethyl esters with glycerol under ultrasound irradiation in solvent free system was developed. Optimization of reaction parameters shows that a high conversion of above 97.4% can be obtained under the following conditions: phenolic acid ethyl esters to glycerol molar ratio of 1:10, with 6% catalyst (Novozym 435), at 60°C and 200rpm, with ultrasound input of 250W, at 20kHz frequency. Compared to the conventional stirring method, the activation energy for phenolic acid ethyl esters conversion was decreased from 65.0kJ/mol to 32.1kJ/mol under ultrasound promotion; the apparent kinetic constant (V m /K m ) increased above 1.2-folds; the lipase amount decreased to 50%; the time required for the maximum conversion reduced up to 3-folds without damaging the lipase activity, which is the fastest report for enzymatic synthesis of MPAs., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this study, Candida lipolytica lipase (CLL) was immobilized on magnetic multi-walled carbon nanotubes (mMWCNTs) via hydrophobic and cation-exchange interaction. The resultant immobilized CLL showed much better thermal stability, biocatalyst activity and easier recycling than the free form. A method for efficient enzymatic acidolysis of tripalmitin (PPP) with oleic acid (OA), to produce OPO-rich TAGs, was developed, using the immobilized CLL as the biocatalyst. Under optimized conditions (2% water, 20mg/ml enzyme, 1:6 PPP/OA, 50°C, 2h), the content of OPO in the final product reached 46.5%. CLL@mMWCNTs had a better activity and manipulative stability than commercial lipases. More importantly, the feasibility of CLL@mMWCNTs was also validated in the practical production of OPO-rich TAGs, using lard and restructured palm oil as the raw material. These results suggest that CLL@mMWCNTs is a promising biocatalyst for the OPO-rich TAGs production and will be helpful for the infant formula industry., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Herein, a promising carrier, graphene oxide (GO) decorated with ZnO nanoparticles, denoted as GO/ZnO composite, has been designed and constructed. This carrier was characterized by X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetry. Then, Candida rugosa lipase (CRL) was immobilized onto the GO-based materials via physical adsorption. Our results indicated that the lipase loading amount on the GO/ZnO composites was about 73.52 mg of protein per g. In the activity assay, the novel immobilized lipase GO/ZnO@CRL, exhibited particularly excellent performance in terms of thermostability and reusability. Within 30 min at 50 °C, the free lipase, GO@CRL and ZnO@CRL had respectively lost 64%, 62% and 41% of their initial activity. However, GO/ZnO@CRL still retained its activity of 63% after 180 min at 50 °C. After reuse of the GO/ZnO@CRL 14 times, 90% of the initial activity can be recovered. Meanwhile, the relative activity of GO@CRL and ZnO@CRL was 28% and 23% under uniform conditions. Hence, GO-decorated ZnO nanoparticles may possess great potential as carriers for immobilizing lipase in a wide range of applications., Competing Interests: The authors declare no conflict of interest.

Objectives: To identify novel cold-active lipases from fungal sources and improve their production by heterologous expression in Pichia pastoris., Results: A novel cold-active lipase gene (ReLipB) from Rhizomucor endophyticus was cloned. ReLipB was expressed at a high level in Pichia pastoris using high cell-density fermentation in a 5-l fermentor with the highest lipase activity of 1395 U/ml. The recombinant lipase (RelipB) was purified and biochemically characterized. ReLipB was most active at pH 7.5 and 25 °C. It was stable from pH 4.5-9.0. It exhibited broad substrate specificity towards p-nitrophenyl (pNP) esters (C 2 -C 16 ) and triacylglycerols (C 2 -C 12 ), showing the highest specific activities towards pNP laurate (231 U/mg) and tricaprylin (1840 U/mg), respectively. In addition, the enzyme displayed excellent stability with high concentrations of organic solvents including cyclohexane, n-hexane, n-heptane, isooctane and petroleum ester and surfactants., Conclusions: A novel cold-active lipase from Rhizomucor endophyticus was identified, expressed at a high level and biochemically characterized. The high yield and unique enzymatic properties make this lipase of some potential for industrial applications.

Although Burkholderia cepacia lipase ( BCL ) has been proved to be a potential catalyst for chiral resolution, it is rarely applied in industry because of the low catalysis activity and poor stability of the free form. In this article, BCL was immobilized on the phenyl-modified ordered mesoporous silica (Ph-OMMs) to obtain a novel immobilized lipase. Benefits from the bottle-neck mesoporous structure, high loading of BCL could be completed within only 15 min. When BCL @Ph-OMMs was used as a catalyst for the resolution of 1-phenylethanol, up to 50% conversion with more than 99% ee s was obtained within only 25 min, which is about 65-folds faster than that of the free lipase. Stabilized BCL @Ph-OMMs was successfully used for the ultrafast resolution of six secondary alcohols by selectivity transesterification, which reached high conversion (50%) and high enantioselectivity (≥99%) within 20–180 min. The activity of BCL @Ph-OMMs was kept relatively constant in 50 consecutive cycles, which is the best result among the reported immobilized lipases. The study suggests that BCL @Ph-OMMs is an attractive catalyst in industrial applications. [ABSTRACT FROM AUTHOR]