Rhizomucor miehei lipase immobilized on reinforced chitosan–chitin nanowhiskers support for synthesis of eugenyl benzoate

Designing Sites in Heterogeneous Catalysis: Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts?

A critical review of different prominent nanotechnologies adapted to catalysis is provided, with focus on how they contribute to the improvement of selectivity in heterogeneous catalysis. Ways to modify catalytic sites range from the use of the reversible or irreversible adsorption of molecular modifiers to the immobilization or tethering of homogeneous catalysts and the development of well-defined catalytic sites on solid surfaces. The latter covers methods for the dispersion of single-atom sites within solid supports as well as the use of complex nanostructures, and it includes the post-modification of materials via processes such as silylation and atomic layer deposition. All these methodologies exhibit both advantages and limitations, but all offer new avenues for the design of catalysts for specific applications. Because of the high cost of most nanotechnologies and the fact that the resulting materials may exhibit limited thermal or chemical stability, they may be best aimed at improving the selective synthesis of high value-added chemicals, to be incorporated in organic synthesis schemes, but other applications are being explored as well to address problems in energy production, for instance, and to design greener chemical processes. The details of each of these approaches are discussed, and representative examples are provided. We conclude with some general remarks on the future of this field.

Application of Rhizomucor miehei lipase-displaying Pichia pastoris whole cell for biodiesel production using agro-industrial residuals as substrate

This work aimed the application of a new biocatalyst for biodiesel production from residual agro-industrial fatty acids. A recombinant Pichia pastoris displaying lipase from Rhizomucor miehei (RML) on the cell surface, using the PIR-1 anchor system, were prepared using glycerol as the carbon source. The biocatalyst, named RML-PIR1 showed optimum temperature of 45 °C (74.0 U/L). The stability tests resulted in t_1/2 of 3.49 and 2.15 h at 40 and 45 °C, respectively. RML-PIR1 was applied in esterification reactions using industrial co-products as substrates, palm fatty acid distillate (PFAD) and soybean fatty acid distillate (SFAD). The highest productivity was observed for SFAD after 48 h presenting 79.1% of conversion using only 10% of biocatalyst and free-solvent system. This is about ca. eight times higher than commercial free RML in the same conditions. The stabilizing agents study revealed that the treatment using glutaraldehyde (GA) and poly(ethylene glycol) (PEG) enabled increased stability and reuse of biocatalyst. It was observed by SEM analysis that the treatment modified the cell morphology. RML-PIR1-GA presented 87.9% of the initial activity after 6 reuses, whilst the activity of unmodified RML-PIR decreased by 40% after the first use. These results were superior to those obtained in the literature, making this new biocatalyst promising for biotechnological applications, such as the production of biofuels on a large scale.

Current Status and Future Perspectives of Supports and Protocols for Enzyme Immobilization

The market for industrial enzymes has witnessed constant growth, which is currently around 7% a year, projected to reach $10.5 billion in 2024. Lipases are hydrolase enzymes naturally responsible for triglyceride hydrolysis. They are the most expansively used industrial biocatalysts, with wide application in a broad range of industries. However, these biocatalytic processes are usually limited by the low stability of the enzyme, the half-life time, and the processes required to solve these problems are complex and lack application feasibility at the industrial scale. Emerging technologies create new materials for enzyme carriers and sophisticate the well-known immobilization principles to produce more robust, eco-friendlier, and cheaper biocatalysts. Therefore, this review discusses the trending studies and industrial applications of the materials and protocols for lipase immobilization, analyzing their advantages and disadvantages. Finally, it summarizes the current challenges and potential alternatives for lipases at the industrial level.

Lipase From Rhizomucor miehei Immobilized on Magnetic Nanoparticles: Performance in Fatty Acid Ethyl Ester (FAEE) Optimized Production by the Taguchi Method

In this communication, it was evaluated the production of fatty acid ethyl ester (FAAE) from the free fatty acids of babassu oil catalyzed by lipase from Rhizomucor miehei (RML) immobilized on magnetic nanoparticles (MNP) coated with 3-aminopropyltriethoxysilane (APTES), Fe₃O₄@APTES-RML or RML-MNP for short. MNPs were prepared by co-precipitation coated with 3-aminopropyltriethoxysilane and used as a support to immobilize RML (immobilization yield: 94.7 ± 1.0%; biocatalyst activity: 341.3 ± 1.2 U_p–NPB/g), which were also activated with glutaraldehyde and then used to immobilize RML (immobilization yield: 91.9 ± 0.2%; biocatalyst activity: 199.6 ± 3.5 U_p–NPB/g). RML-MNP was characterized by X-Ray Powder Diffraction (XRPD), Fourier Transform-Infrared (FTIR) spectroscopy and Scanning Electron Microscope (SEM), proving the incorporation and immobilization of RML on the APTES matrix. In addition, the immobilized biocatalyst presented at 60°C a half-life 16–19 times greater than that of the soluble lipase in the pH range 5–10. RML and RML-MNP showed higher activity at pH 7; the immobilized enzyme was more active than the free enzyme in the pH range (5–10) analyzed. For the production of fatty acid ethyl ester, under optimal conditions [40°C, 6 h, 1:1 (FFAs/alcohol)] determined by the Taguchi method, it was possible to obtain conversion of 81.7 ± 0.7% using 5% of RML-MNP.

Robust Magnetized Oil Palm Leaves Ash Nanosilica Composite as Lipase Support: Immobilization Protocol and Efficacy Study

Strategies to immobilize the individual enzymes are crucial for enhancing catalytic applicability and require a controlled immobilization process. Herein, protocol for immobilizing Candida rugosa lipase (CRL) onto modified magnetic silica derived from oil palm leaves ash (OPLA) was optimized for the effects of concentration of CRL, immobilization time, and temperature, monitored by titrimetric and spectrometric methods. XRD and TGA-DTG spectrometric observations indicated that OPLA-silica was well coated over magnetite (SiO₂-MNPs) and CRLs were uniformly bound by covalent bonds to SiO₂-MNPs (CRL/Gl-A-SiO₂-MNPs). The optimized immobilization protocol showed that in the preparation of CRL/Gl-A-SiO₂-MNPs, CRL with 68.3 mg/g protein loading and 74.6 U/g specific activity was achieved using 5 mg/mL of CRL, with an immobilization time of 12 h at 25 °C. The present work also demonstrated that acid-pretreated OPLA is a potential source of renewable silica, envisioning its applicability for practical use in enzymatic catalysis on solid support.