Improvement of biodiesel production from palm oil by co-immobilization of Thermomyces lanuginosa lipase and Candida antarctica lipase B: Optimization using response surface methodology

Fabrication of immobilized lipases from Candida rugosa on hierarchical mesoporous silica for enzymatic enrichment of ω-3 polyunsaturated fatty acids by selective hydrolysis

In this study, lipase from Candida rugosa was immobilized on hydrophobic hierarchical porous hollow silica microsphere (HPHSM-C3) via adsorption. The prepared biocatalyst HPHSM-C3@CRL exhibited higher activity, thermal and pH stability. HPHSM-C3@CRL remained 70.2% of initial activity after 30 days of storage at 24 °C and 50.4% of initial activity after 10 cycles. Moreover, HPHSM-C3@CRL was utilized in enzymatic enrichment of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in glycerides, achieving ω-3 PUFAs content of 53.42% with the hydrolysis rate of 48.78% under optimal condition. The Km and Vmax value of HPHSM-C3@CRL was 42.2% lower and 63.5% higher than those of CRL, respectively. The 3D structure analysis of CRL, substrates and pore structure of HPHSM-C3 suggested that the hierarchical pore improved activity and selectivity of immobilized lipase. This result demonstrated that HPHSM-C3@CRL may be an effective biocatalyst for the enzymatic enrichment of ω-3 PUFAs in food industries.

Improvement of combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase and maltogenic amylase by functionalization of cross-linker for maltooligosaccharides synthesis

Combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase (CGTase) and maltogenic amylase (Mag1) from Bacillus lehensis G1 (Combi-CLEAs-CM) were successfully developed to synthesis maltooligosaccharides (MOS). Yet, the poor cross-linking performance between chitosan (cross-linker) and enzymes resulting low activity recovery and catalytic efficiency. In this study, we proposed the functionalization of cross-linkers with the integration of computational analysis to study the influences of different functional group on cross-linkers in combi-CLEAs development. From in-silico analysis, O-carboxymethyl chitosan (OCMCS) with the highest binding affinity toward both enzymes was chosen and showed alignment with the experimental result, in which OCMCS was synthesized as cross-linker to develop improved activity recovery of Combi-CLEAs-CM-ocmcs (74 %). The thermal stability and deactivation energy (205.86 kJ/mol) of Combi-CLEAs-CM-ocmcs were found to be higher than Combi-CLEAs-CM (192.59 kJ/mol). The introduction of longer side chain of carboxymethyl group led to a more flexible structure of Combi-CLEAs-CM-ocmcs. This alteration significantly reduced the Km value of Combi-CLEAs-CM-ocmcs by about 3.64-fold and resulted in a greater Kcat/Km (3.63-fold higher) as compared to Combi-CLEAs-CM. Moreover, Combi-CLEAs-CM-ocmcs improved the reusability with retained >50 % of activity while Combi-CLEAs-CM only 36.18 % after five cycles. Finally, maximum MOS production (777.46 mg/g) was obtained by Combi-CLEAs-CM-ocmcs after optimization using response surface methodology.

Lipase-mediated alcoholysis for in situ production of ester bioaromas in licuri oil for cosmetic applications

Bioaromas can be produced by lipases either through their hydrolytic or (trans)esterifying activities. Therefore, this work reports the development of a lipase-catalyzed biotransformed licuri oil, forming volatile ethyl esters with odor notes resembling tropical fruits. Ethyl octanoate formation was promoted when 7.0 % (m/v) Lipozyme 435® was used to convert a grain alcohol:licuri oil mixture (51:49, v/v) at 58ºC and 70 rpm for 6 hours. The biotransformed oil has shown antimicrobial activity against Staphylococcus hominis, S. epidermidis, and Corynebacterium xerosis, bacteria associated with bad skin odor. Finally, this biotransformed oil was used without further treatments (e.g., recovery or purification procedures) to prepare two cosmetic formulations (in a dosage of 1.5 %), aiming for both fragrant and deodorant activity.

Optimization of Ti-PA efficiently catalytic the alcoholysis of waste PET using response surface methodology

A new type of titanium phthalate (Ti-PA) catalyst was prepared by exchange method of phthalic acid and isopropyl titanate, which is never been reported before. The Ti-PA catalyst was characterized by FT-IR, TG, Uv-vis, BET, SEM, and EDS. The Ti-PA catalyst shows good catalytic activity in the alcoholysis reaction of polyethylene terephthalate (PET) and optimal experimental conditions for the alcoholysis process were optimized by response surface methodology; the Ti-PA catalyst provided a BHET yield of 81.98% for reaction lasting 3.98 h at 191 °C of 0.86% catalyst and 13.7 ml ethylene glycol; the model has good reliability. The kinetics and reaction mechanism of the process were explored and apparent activation energy is 75.52 kJ/mol. Finally, the good catalytic activity of Ti-PA was illustrated by comparing it with currently reported catalysts.

Nano-based biofuel production from low-cost lignocellulose biomass: environmental sustainability and economic approach

The use of nanomaterials in biofuel production from lignocellulosic biomass offers a promising approach to simultaneously address environmental sustainability and economic viability. This review provides an overview of the environmental and economic implications of integrating nanotechnology into biofuel production from low-cost lignocellulosic biomass. In this review, we highlight the potential benefits and challenges of nano-based biofuel production. Nanomaterials provide opportunities to improve feedstock pretreatment, enzymatic hydrolysis, fermentation, and catalysis, resulting in enhanced process efficiency, lower energy consumption, and reduced environmental impact. Conducting life cycle assessments is crucial for evaluating the overall environmental footprint of biofuel production. An economic perspective that focuses on the cost implications of utilizing nanomaterials in biofuel production is also discussed. A comprehensive understanding of both environmental and economic dimensions is essential to fully harness the potential of nanomaterials in biofuel production from lignocellulosic biomass and to move towards sustainable future energy.

Hyperactivation of lipases by immobilization on superhydrophobic graphene quantum dots inorganic hybrid nanoflower

Various nanoflowers are synthesized for enzyme immobilization. In order to increase the activity of nanoflowers, in this study, 3D flower-like structured organic-inorganic hybrid nanoflowers (hNFs) with various lipases Rhizomucor miehei lipase (RML), Candida antarctica lipase B (CALB), Humicola insolens lipase (HIL), Thermomyces lanuginosus lipase (TLL), Eversa® Transform 2.0 (ET) a genetically modified enzyme derived of TLL and graphene quantum dots (GQDs) were prepared and characterized.Lipase hNFs [lipase-(Cu/Co)3(PO4)2] and lipase@GQDs hNFs [lipase@GQDs-(Cu/Co)3(PO4)2] were straightforwardly prepared through mixing with metal ion (Cu2+or Co2+) aqueous solutions with or without GQDs. The ET@GQDs-(Cu)3(PO4)2 hNFs demonstrated 687 % higher activity than ET-(Cu)3(PO4)2 hNFs and 650 % higher activity than the free ET. Similar results were also observed with other lipase hybrid nanoflowers. For example, TLL@GQDs-(Cu)3(PO4)2 hNFs exhibited a 557 % higher activity than TLL-(Cu)3(PO4)2 hNFs and a 463 % higher activity than free TLL. Additionally, TLL@GQDs-(Co)3(PO4)2 hNFs showed a 141 % higher activity than TLL-(Co)3(PO4)2 hNFs and a 304 % higher activity than free TLL. Upon examining pH and thermal stability, it was revealed that lipase@GQDs hNFs exhibited higher activity compared to free lipase and other hNFs without GQDs. The effect of metal ions, enzyme concentrations and amount of GQDs on the morphology and enzyme activity of the lipase-hNFs was examined.

The Isolation, Identification and Immobilization Method of Three Novel Enzymes with Diosgenin-Producing Activity Derived from an Aspergillus flavus

Diosgenin is an important raw material used in the synthesis of steroid drugs, and it is widely used in the pharmaceutical industry. The traditional method of producing diosgenin is through using raw materials provided via the plant Dioscorea zingiberensis C. H. Wright (DZW), which is subsequently industrially hydrolyzed using a high quantity of hydrochloric and sulfuric acids at temperatures ranging from 70 °C to 175 °C. This process results in a significant amount of unmanageable wastewater, creates issues of severe environmental pollution and consumes high quantities of energy. As an alternative, the enzymolysis of DZW to produce diosgenin is an environmentally and friendly method with wide-ranging prospects for its application. However, there are still only a few enzymes that are suitable for production on an industrial scale. In this study, three new key enzymes, E1, E2, and E3, with a high conversion stability of diosgenin, were isolated and identified using an enzyme-linked-substrate autography strategy. HPLC-MS/MS identification showed that E1, a 134.45 kDa protein with 1019 amino acids (AAs), is a zinc-dependent protein similar to the M16 family. E2, a 97.89 kDa protein with 910 AAs, is a type of endo-β-1,3-glucanase. E3, a 51.6 kDa protein with 476 AAs, is a type of Xaa-Pro aminopeptidase. In addition, the method to immobilize these proteins was optimized, and stability was achieved. The results show that the optimal immobilization parameters are 3.5% sodium alginate, 3.45% calcium chloride concentration, 1.4 h fixed time, and pH 8.8; and the recovery rate of enzyme activity can reach 43.98%. A level of 70.3% relative enzyme activity can be obtained after employing six cycles of the optimized technology. Compared with free enzymes, immobilized enzymes have improved stability, acid and alkaline resistance and reusability, which are conducive to large-scale industrial production.

Effects of kosmotropic, chaotropic, and neutral salts on Candida antarctica B lipase: An analysis of the secondary structure and its hydrolytic activity on triglycerides

The effects of different concentrations of Hofmeister salts on the hydrolytic activity on triglycerides and the secondary structure of lipase B from Candida antarctica (CALB) were investigated. Structural changes after short- and long-time incubation at high salt concentrations were determined using circular dichroism (CD), fluorescence, and RMSD-RMSF simulations. At 5.2 M NaCl, the hydrolytic activity of CALB on tributyrin (TC4) and trioctanoin (TC8) was enhanced by 1.5 (from 817 ± 3.9 to 1228 ± 4.3 U/mg)- and 8.7 (from 25 ± 0.3 to 218 ± 2.3 U/mg)-folds compared with 0.15 M NaCl, respectively at pH 7.0 and 40 °C. An activity activation was seen with other salts tested; however, long-time incubation (24 h) did not result in retention of the activation effect for any of the salts tested. Secondary structure CD and fluorescence spectra showed that long-time incubation with NaCl, KCl, and CsCl provokes a compact structure without loss of native conformation, whereas chaotropic LiCl and CaCl2 induced an increase in the α-helical content, and kosmotropic Na2SO4 provoked a molten globule state with rich β-sheet content. The RMSD-RMSF simulation agreed with the CD analysis, highlighting a principal salt-induced effect at the α-helix 5 region, promoting two different conformational states (open and closed) depending on the type and concentration of salt. Lastly, an increase in the interfacial tension occurred when high salt concentrations were added to the reaction media, affecting the catalytic properties. The results indicate that high-salt environments, such as 2-5.2 M NaCl, can be used to increase the lipolytic activity of CALB on TC4 and TC8.

Novel biocatalysts based on enzymes in complexes with nano- and micromaterials

In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.

Preparation of water-insoluble lignin nanoparticles by deep eutectic solvent and its application as a versatile and biocompatible support for the immobilization of α-amylase

As one of the most abundant biopolymers, lignin is a widely available resource. However, its potential largely remains untapped, with most of it ending up as waste from industries like paper production, pulp processing, and bio-refining. The research undertaken in this study focused on the extraction of lignin from agroforestry waste using a deep eutectic solvent (DES) as a carrier for α-amylase immobilization, resulting in high stability and reusability. Several techniques, including Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and the Brunauer-Emmett-Teller (BET) method were employed to examine the structure and morphology of both the extracted lignin and the immobilized enzyme. The temperature used to recover lignin by DES would affect immobilization efficiency and enzyme loading by influencing its specific surface area, pore size, and volume distribution. Investigations using Nuclear Overhauser Effect Spectroscopy (NOESY) uncovered that the hydroxyl groups in G, H, and S units and the β-O-4 structure of lignin primarily serve as binding sites for enzyme molecules. Immobilized α-amylase demonstrated a higher pH and thermal stability level, with an optimal pH of 7.0 and temperature of 100 °C, compared to the free enzyme, which exhibited optimal activity at a pH of 6.5 and temperature of 90 °C. Importantly, immobilized α-amylase retained >80 % of its initial activity even after 28 days at room temperature, and it maintained 70 % of its activity after being reused 12 times. These findings strongly suggest that lignin derived from agroforestry residues holds promising potential as a future versatile immobilization material, a prospect integral to society's sustainable development.

Optimization of Ti-BA efficiently for the catalytic alcoholysis of waste PET using response surface methodology

A titanium benzoate (Ti-BA) catalyst was prepared by hydrothermal method, which has an ordered eight-face structure, and was used for polyethylene terephthalate (PET) depolymerization. With bis(2-hydroxyethyl)terephthalate (BHET) as the target molecule and ethylene glycol (EG) as the solvent, the best reaction conditions for catalytic alcoholysis via a PET alcoholic solution were investigated via response surface experiments and found to be a EG/PET mass ratio of 3.59, temperature of 217 °C and reaction time of 3.3 h. Under these conditions, the amount of the catalyst required was only 2% of the mass of the PET, and the yield of BHET reached 90.01% and under the same conditions, the yield of BHET could still reach 80.1%. Based on the experimental results, the mechanism of alcoholysis, Ti-BA catalyst activated ethylene glycol deprotonation to achieve the progressive degradation of polymers. This experiment provides a reference for the degradation of polymer waste and other transesterification reactions.

Co-Immobilization of Lipases with Different Specificities for Efficient and Recyclable Biodiesel Production from Waste Oils: Optimization Using Response Surface Methodology

Lipase-catalyzed transesterification is a promising and sustainable approach to producing biodiesel. To achieve highly efficient conversion of heterogeneous oils, combining the specificities and advantages of different lipases is an attractive strategy. To this end, highly active Thermomyces lanuginosus lipase (1,3-specific) and stable Burkholderia cepacia lipase (non-specific) were covalently co-immobilized on 3-glycidyloxypropyltrimethoxysilane (3-GPTMS) modified Fe₃O₄ magnetic nanoparticles (co-BCL-TLL@Fe₃O₄). The co-immobilization process was optimized using response surface methodology (RSM). The obtained co-BCL-TLL@Fe₃O₄ exhibited a significant improvement in activity and reaction rate compared with mono and combined-use lipases, achieving 92.9% yield after 6 h under optimal conditions, while individually immobilized TLL, immobilized BCL and their combinations exhibited yields of 63.3%, 74.2% and 70.6%, respectively. Notably, co-BCL-TLL@Fe₃O₄ achieved 90-98% biodiesel yields after 12 h using six different feedstocks, demonstrating the perfect synergistic effect of BCL and TLL remarkably motivated in co-immobilization. Furthermore, co-BCL-TLL@Fe₃O₄ could maintain 77% of initial activity after nine cycles by removing methanol and glycerol from catalyst surface, accomplished by washing with t-butanol. The high catalytic efficiency, wide substrate adaptability and favorable reusability of co-BCL-TLL@Fe₃O₄ suggest that it will be an economical and effective biocatalyst for further applications.

Climatic Chamber Stability Tests of Lipase-Catalytic Octyl-Sepharose Systems

The application of the climatic chamber presented in this paper to assess the storage stability of immobilized lipases is a new approach characterized by the potential of unifying the study conditions of biocatalysts created in various laboratories. The data achieved from storing lipases in the climatic chambers may be crucial for the chemical and pharmaceutical industry. Our paper describes the developed protocols for immobilization via interfacial activation of lipase B from Candida antarctica (CALB) and lipase OF from Candida rugosa (CRL-OF) on the Octyl-Sepharose CL-4B support. Optimization included buffers with different pH values of 4–9 and a wide range of ionic strength from 5 mM to 700 mM. It has been shown that the optimal medium for the CALB immobilization process on the tested support is a citrate buffer at pH 4 and high ionic strength of 500 mM. Implementing new optimal procedures enabled the hyperactivation of immobilized CALB (recovery activity 116.10 ± 1.70%) under the applicable reaction conditions using olive oil as a substrate. Importantly, CALB storage stability tests performed in a climatic chamber under drastic temperature and humidity conditions proved good stability of the developed biocatalyst (residual activity 218 ± 7.3% of dry form, after 7 days). At the same time, the low storage stability of CRL OF in a climatic chamber was demonstrated. It should be emphasized that the use of a climatic chamber to test the storage stability of a dry form of the studied lipases immobilized on Octyl-Sepharose CL-4B is, to our knowledge, described for the first time in the literature.

The vital use of isocyanide-based multicomponent reactions (MCR) in chemical synthesis

Multicomponent (MCRs) reactions are classified as one-pot reaction where more than two starting materials are employed to form a single product that contains the building blocks of the starting components. MCRs are considered a convenient approach in synthetic chemistry and have many advantages over the traditional one or two-component reaction, by reducing the number of sequential multiple steps required and often producing better yields. This chapter dissects the use of isocyanide-based MCRs and the elegant chemistry that they offer to build useful scaffolds in the chemical synthetic field. In addition MCRs are considered as one of the recognisable options for increasing “greenness” during the synthesis of pharmaceutical and industrial products.

Designing multifunctional biocatalytic cascade system by multi-enzyme co-immobilization on biopolymers and nanostructured materials

In recent decades, enzyme-based biocatalytic systems have garnered increasing interest in industrial and applied research for catalysis and organic chemistry. Many enzymatic reactions have been applied to sustainable and environmentally friendly production processes, particularly in the pharmaceutical, fine chemicals, and flavor/fragrance industries. However, only a fraction of the enzymes available has been stepped up towards industrial-scale manufacturing due to low enzyme stability and challenging separation, recovery, and reusability. In this context, immobilization and co-immobilization in robust support materials have emerged as valuable strategies to overcome these inadequacies by facilitating repeated or continuous batch operations and downstream processes. To further reduce separations, it can be advantageous to use multiple enzymes at once in one pot. Enzyme co-immobilization enables biocatalytic synergism and reusability, boosting process efficiency and cost-effectiveness. Several studies on multi-enzyme immobilization and co-localization propose kinetic advantages of the enhanced turnover number for multiple enzymes. This review spotlights recent progress in developing versatile biocatalytic cascade systems by multi-enzyme co-immobilization on environmentally friendly biopolymers and nanostructured materials and their application scope in the chemical and biotechnological industries. After a succinct overview of carrier-based and carrier-free immobilization/co-immobilizations, co-immobilization of enzymes on a range of biopolymer and nanomaterials-based supports is thoroughly compiled with contemporary and state-of-the-art examples. This study provides a new horizon in developing effective and innovative multi-enzymatic systems with new possibilities to fully harness the adventure of biocatalytic systems.

Coimmobilized enzymes as versatile biocatalytic tools for biomass valorization and remediation of environmental contaminants - A review

Due to stringent regulatory norms, waste processing faces confrontations and challenges in adapting technology for effective management through a convenient and economical system. At the global level, attempts are underway to achieve a green and sustainable treatment for the valorization of lignocellulosic biomass as well as organic contaminants in wastewater. Enzymatic treatment in the environmental aspect thrived on being the promising rapid strategy that appeased the aforementioned predicament. On that account, coimmobilization of various enzymes on single support enhances the catalytic activity ensuing operational stability with industrial applications. This review pivoted towards the coimmobilization of enzymes on diverse supports and their applications in biomass conversion to industrial value-added products and removal of contaminants in wastewater. The limelight of this study chronicles the unique breakthroughs in biotechnology for the production of reusable biocatalysts, which inculcating various enzymes towards the scope of environment application.

Biochemical and Physical Characterization of Immobilized Candida rugosa Lipase on Metal Oxide Hybrid Support

Enzyme immobilization on inorganic materials is gaining more attention with the potential characteristics of high-surface-area-to-volume ratios, increasing the efficiency of enzyme loading on the support. Metal oxide hybrid support was prepared by a wetness impregnation of five metal precursors, including CaO, CuO, MgO, NiO, and ZnO, on Al2O3 and used as a support for the immobilization of Candida rugosa lipase (CRL) by adsorption. Maximum activity recovery (70.6%) and immobilization efficiency (63.2%) were obtained after optimization of five parameters using response surface methodology (RSM) by Box–Behnken design (BBD). The biochemical properties of immobilized CRL showed high thermostability up to 70 °C and a wide range in pH stability (pH 4–10). TGA-DTA and FTIR analysis were conducted, verifying thermo-decomposition of lipase and the presence of an amide bond. FESEM-EDX showed the homogeneous distribution and high dispersion of magnesium and CRL on MgO-Al2O3, while a nitrogen adsorption–desorption study confirmed MgO-Al2O3 as a mesoporous material. CRL/MgO-Al2O3 can be reused for up to 12 cycles and it demonstrated high tolerance in solvents (ethanol, isopropanol, methanol, and tert-butanol) compared to free CRL.

Biocatalytic decarboxylative Michael addition for synthesis of 1,4-benzoxazinone derivatives

The Candida antarctica lipase B (Novozym 435) is found to catalyze a novel decarboxylative Michael addition in vinylogous carbamate systems for the synthesis of 1,4-benzoxazinone derivatives. The reaction goes through Michael addition, ester hydrolysis and decarboxylation. A possible mechanism is suggested, with simultaneous lipase-catalyzed Michael addition and ester hydrolysis. The present methodology offers formation of complex products through multi-step reactions in a one pot process under mild and facile reaction conditions with moderate to high yields (51–90%) and no side product formation. The reaction seems to be is a great example of enzymatic promiscuity.

Chemical amination of immobilized enzymes for enzyme coimmobilization: Reuse of the most stable immobilized and modified enzyme

Although Lecitase and the lipase from Thermomyces lanuginosus (TLL) could be coimmobilized on octyl-agarose, the stability of Lecitase was lower than that of TLL causing the user to discard active immobilized TLL when Lecitase was inactivated. Here, we propose the chemical amination of immobilized TLL to ionically exchange Lecitase on immobilized TLL, which should be released to the medium after its inactivation by incubation at high ionic strength. Using conditions where Lecitase was only adsorbed on immobilized TLL after its amination, the combibiocatalyst was produced. Unfortunately, the release of Lecitase was not possible using just high ionic strength solutions, and if detergent was added, TLL was also released from the support. This occurred when using 0.25 M ammonium sulfate, Lecitase did not immobilize on aminated TLL. That makes the use octyl-vinylsulfone supports necessary to irreversibly immobilize TLL, and after blocking with ethylendiamine, the immobilized TLL was aminated. Lecitase immobilized and released from this biocatalyst using 0.25 M ammonium sulfate and 0.1% Triton X-100. That way, a coimmobilized TLL and Lecitase biocatalyst could be produced, and after Lecitase inactivation, it could be released and the immobilized, aminated, and fully active TLL could be utilized to build a new combibiocatalyst.

A Review of the Existing Potentials in Biodiesel Production in Iran

Petroleum fuel plays an important role in industry, transportation, agriculture and other related industries in Iran. Iran has about 9.5% of the world’s total oil reserves in 2020 and is ranked 4th in the world. The presence of sufficient conventional fossil fuels for internal combustion engines has caused environmental problems. If these Iranian fossil fuels were to run out right now, there is no suitable alternative that is just as effective. The need to research alternative fuels in Iran is therefore unavoidable. In this study, the potential and available resources of raw materials, including rapeseed oil, palm oil, fish oil, waste oil, algae, animal fat, olive oil and jatropha oil for biodiesel production in different regions of Iran, have been reviewed. Given the potentials and resources described in this study, it is hoped that the findings of this study will play an important role in biodiesel production in Iran in the future and stimulate more researchers to create biodiesel from existing sources. It is also expected that this study will increase the attention of the governmental and non-governmental organizations in Iran to the existing resources for biodiesel production and development of these resources and get rid of the existing problems of fossil fuels by investing in this field.

Coimmobilization of lipases exhibiting three very different stability ranges. Reuse of the active enzymes and selective discarding of the inactivated ones

Lipase B from Candida antarctica (CALB) and lipases from Candida rugosa (CRL) and Rhizomucor miehei (RML) have been coimmobilized on octyl and octyl-Asp agarose beads. CALB was much more stable than CRL, that was significantly more stable than RML. This forces the user to discard immobilized CALB and CRL when only RML has been inactivated, or immobilized CALB when CRL have been inactivated. To solve this problem, a new strategy has been proposed using three different immobilization protocols. CALB was covalently immobilized on octyl-vinyl sulfone agarose and blocked with Asp. Then, CRL was immobilized via interfacial activation. After coating both immobilized enzymes with polyethylenimine, RML could be immobilized via ion exchange. That way, by incubating in ammonium sulfate solutions, inactivated RML could be released enabling the reuse of coimmobilized CRL and CALB to build a new combi-lipase. Incubating in triton and ammonium sulfate solutions, it was possible to release inactivated CRL and RML, enabling the reuse of immobilized CALB when CRL was inactivated. These cycles could be repeated for 3 full cycles, maintaining the activity of the active and immobilized enzymes.

Enhancing the methanol tolerance of Candida antarctica lipase B by saturation mutagenesis for biodiesel preparation

Methanol tolerance of lipase is one of the important factors affecting its esterification ability in biodiesel preparation. By B factor indicated prediction of Candida antarctica lipase B (CalB) surface amino acids, eight sites (Val¹³⁹, Ala¹⁴⁶, Leu¹⁴⁷, Pro²¹⁸, Val²⁸⁶, Ala²⁸⁷, Val³⁰⁶, and Gly³⁰⁷) with high B value indicating more flexibility were chosen to perform saturation mutagenesis. High-methanol-tolerant variants, CalB-P218W and -V306N, created larger haloes on emulsified tributyrin solid plate including 15% (v/v) methanol and showed 19% and 31% higher activity over wild-type CalB (CalB-WT), respectively. By modeling, a newly formed hydrogen bond in CalB-V306N and hydrophobic force in CalB-P218W contributing more stability in protein may have resulted in increased methanol tolerance. CalB-P218W and -V306N transesterified the soybean oil into biodiesel at 30 °C by 85% and 89% yield, respectively, over 82% by CalB-WT for 24 h reactions. These results may provide a basis for molecular engineering of CalB and expand its applications in fuel industries. The as-developed semi-rational method could be utilized to enhance the stabilities of many other industrial enzymes.

Enhancement of laccase production from a newly isolated Trichoderma harzianum S7113 using submerged fermentation: Optimization of production medium via central composite design and its application for hydroquinone degradation

Trichoderma harzianum S7113 as an efficient fungal isolate for laccase production was identified using the 18S rRNA sequencing. T. harzianum S7113 attained its maximal laccase production level on the 14^th day of static incubation at 28 °C and pH 5.0 using the inoculum size of 5 discs (14 mm), according to the one factor per time (OFT) method. The most appropriate carbon, organic and inorganic nitrogen sources to promote maximal laccase synthesis were glucose (15 g/L), beef extract (5 g/L), and ammonium chloride (4 g/L), respectively. Results of Response Surface Methodology (RSM) revealed that glucose, meat extract, and ammonium chloride concentrations of 17.54, 7.17, and 4.36 g/L respectively, at a pH value of 6.74 are the favorite conditions for high titer production. The ANOVA analysis highlighted an excellent match between the actual experimental results and the model predicted laccase production levels. The biodegradation of hydroquinone (HQ) by T. harzianum S7113 laccase was most efficient in the pH range of 5.0 to 6.5. The increase in laccase concentration led to a significant increase in the HQ conversion to get a biodegradation rate of 92 ± 2.6% with a laccase concentration of 0.75 U/mL after 3 h of reaction.

Co-Immobilization of Rhizopus oryzae and Candida rugosa Lipases onto mMWCNTs@4-arm-PEG-NH2-A Novel Magnetic Nanotube-Polyethylene Glycol Amine Composite-And Its Applications for Biodiesel Production

This article describes the successful synthesis of a novel nanocomposite of superparamagnetic multi-walled nanotubes with a four-arm polyethylene glycol amine polymer (mMWCNTs@4-arm-PEG-NH2). This composite was then employed as a support for the covalent co-immobilization of Rhizopus oryzae and Candida rugosa lipases under appropriate conditions. The co-immobilized lipases (CIL-mMWCNTs@4-arm-PEG-NH2) exhibited maximum specific activity of 99.626U/mg protein, which was 34.5-fold superior to that of free ROL, and its thermal stability was greatly improved. Most significantly, CIL-mMWCNTs@4-arm-PEG-NH2 was used to prepare biodiesel from waste cooking oil under ultrasound conditions, and within 120 min, the biodiesel conversion rate reached 97.64%. This was due to the synergy effect between ROL and CRL and the ultrasound-assisted enzymatic process, resulting in an increased biodiesel yield in a short reaction time. Moreover, after ten reuse cycles, the co-immobilized lipases still retained a biodiesel yield of over 78.55%, exhibiting excellent operational stability that is attractive for practical applications. Consequently, the combined use of a novel designed carrier, the co-immobilized lipases with synergy effect, and the ultrasound-assisted enzymatic reaction exhibited potential prospects for future applications in biodiesel production and various industrial applications.

Temperature-resistant and solvent-tolerant lipases as industrial biocatalysts: Biotechnological approaches and applications

The development of new biocatalytic systems to replace the chemical catalysts, with suitable characteristics in terms of efficiency, stability under high temperature reactions and in the presence of organic solvents, reusability, and eco-friendliness is considered a very important step to move towards the green processes. From this basis, the use of lipase as a catalyst is highly desired for many industrial applications because it offers the reactions in which could be used, stability in harsh conditions, reusability and a greener process. Therefore, the introduction of temperature-resistant and solvent-tolerant lipases have become essential and ideal for industrial applications. Temperature-resistant and solvent-tolerant lipases have been involved in many large-scale applications including biodiesel, detergent, food, pharmaceutical, organic synthesis, biosensing, pulp and paper, textile, animal feed, cosmetics, and leather industry. So, the present review provides a comprehensive overview of the industrial use of lipase. Moreover, special interest in biotechnological and biochemical techniques for enhancing temperature-resistance and solvent-tolerance of lipases to be suitable for the industrial uses.