Adsorption Of Candida Rugosa Lipase Research Articles

Vacuum-assisted adsorption of Candida rugosa lipase with nanotubes for monooleoglycerol synthesis

A surplus of crude glycerol has been produced as a by-product due to the escalating production of biofuels. Utilization of crude glycerol for monoolein production which offers a different approach using the abandoned crude glycerol from the biodiesel sector is the main aim of this study. Immobilized lipase was used in this investigation to catalyse the direct esterification of oleic acid and glycerol, which resulted in monoolein. The immobilized Candida rugosa lipase onto the halloysite nanotubes (HNTs) has shown remarkably promising attainment of lipase activity and loading capacity. The immobilised lipase was optimised for crucial parameters (HNT to lipase ratio, pH, temperature, and pressure) via response surface methodology (RSM). The recommended optimum conditions obtained are pH 6, 38.6 °C, and 0.33 atm (81.92% lipase activity). To analyse influences of reaction period, temperature, mixing rate, and crude glycerol to oleic acid molar ratio on the esterification reaction was carried out using the optimized conditions of immobilization process. The optimum conditions for physically immobilised lipase were to yield 88.97% monoolein produced at 42 °C in a substrate ratio of 1:4 (oleic acid: glycerol) stirred at 200 rotations per minute (rpm) with 16 h’ incubation time. Based on the research's findings, it was confirmed that HNT has good application potential for enzyme immobilization carriers.

Immobilization of Candida Rugosa lipase on Ca/Kit-6 used as bifunctional biocatalysts for the transesterification of coconut oil to biodiesel

Immobilization of Candida Rugosa lipase (CRL) on Ca doped Kit-6 solid was investigated via the adsorption method. Effects of the experimental parameters, such as pH value, temperature, time, and Ca content on the adsorption of CRL on Ca/Kit-6 were studied. In the Ca doped Ca/Kit-6 materials, Ca2+ coexisted in two environments: Ca2+ in CaO nanoparticles and in Ca-O-Si in the framework of Kit-6. There existed three kind of oxygen species: (1) lattice oxygen in CaO and SiO2; (2) Oxygen in structural defects; and (3) non-stoichiometric surface oxygen in OH form. The 0.5Ca/Kit-6 showed the most CRL immobilization capacity and stability under the optimal adsorption condition, which was correlated with its greater amount of basicity resulting from its more non-stoichiometric surface oxygen and oxygen in structural defects as well as more Ca2+ incorporation in the Kit-6 framework. In the production of biodiesel via transesterification of coconut oil, the catalysts showed better catalytic performance under weak basic than acidic condition. Under the optimal reaction conditions (40 °C, pH 7.5, 200 rpm, oil to methanol ratio 1:3 with stepwise addition of methanol, and 0.1 g of CRL/0.5Ca/Kit-6), the coconut oil conversion and biodiesel yield catalyzed with CRL/0.5Ca/Kit-6 was 95 and 98%, respectively. 10wt% water in the reaction mixture promoted the coconut oil transesterification to biodiesel. The CRL/0.5Ca/Kit-6 catalyst possessed bifunctional roles of the enzymatic catalysis role from immobilized CRL and the basic catalysis role from CaO doping. The CRL adsorption modes, water influence and the reaction mechanism of coconut oil transesterification were discussed.

Modelling and optimization of Candida rugosa nanobioconjugates catalysed synthesis of methyl oleate by response surface methodology

Esters, such as methyl oleate, are functionally important compounds in many industrial sectors, mainly as components for manufacturing of emulsifiers, detergents, intermediate stabilizers and wetting agents. Acid functionalization of multi-walled carbon nanotubes (F-MWCNTs) by using a mixture of HNO3 and H2SO4 (1:3, v:v) was employed as the matrix for the adsorption of Candida rugosa lipase (CRL) as nanobioconjugates (CRL-MWCNTs) for the production of methyl oleate. Structural information of the developed CRL-MWCNTs was confirmed using Fourier Transform Infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy, which revealed a successful attachment of CRL onto the F-MWCNTs. Process parameters (reaction time, temperature and alcohol:acid molar ratio) were optimized for high percent conversion of methyl oleate. Structural analysis established that CRL was successfully attached to the surface of the F-MWCNTs. Under the optimized conditions, which were 13.87 h, 51 °C, molar ratio oleic acid:methanol (1:3.80), a high ester yield of 90.90% was attained. Also, under conditions of the shortest reaction time of 6 h, 47.07 °C and acid:methanol ratio of 1:2.54, the CRL-MWCNTs catalysed a 74.51% ester yield. Hence, we established that response surface methodology (RSM) can be a practical technique for the prediction of the conditions that favour the high yield production of methyl oleate. Under optimized conditions, the CRL-MWCNTs nanobioconjugates are potentially good and economical biocatalysts for the production of methyl oleate, as well as other types of commercially important fatty-acid methyl esters.

Sustainable production of the emulsifier methyl oleate by Candida rugosa lipase nanoconjugates

Acid functionalization of multi-walled carbon nanotubes (F-MWCNTs) using a mixture of HNO3 and H2SO4 (1:3, v:v) was used as support materials for the adsorption of Candida rugosa lipase (CRL) as nanoconjugates (CRL-MWCNTs) for producing methyl oleate. To evaluate the competency of the CRL-MWCNTs nanoconjugates, parameters viz. reaction time, surfactant as well as thermostability and reusability were investigated. The characterization of CRL-MWCNTs nanoconjugates using Fourier transform infrared spectroscopy, Field Scanning Electron Microscopy and Transmission Electron Microscopy revealed successful attachment of CRL onto the F-MWCNTs. Utilization of CRL-MWCNTs nanoconjugates resulted in a higher acid conversion in the synthesis of methyl oleate (79.85% at 11h of reaction time) when compared with the free CRL i.e. an approximately 1.5-fold improvement over the free CRL. The highest percentage of esterification (83.62%) was observed following the use of nonionic surfactant when compared with the anionic and cationic ones. The CRL-MWCNTs nanoconjugates could be used up to 5 cycles, retaining 50% of its residual activity. Since the preparation of the CRL-MWCNTs nanoconjugates was facile and cheap while producing reasonable yield, the CRL-MWCNTs nanoconjugates developed here were found as promising biocatalysts for the production of methyl oleate.

Simple adsorption of Candida rugosa lipase onto multi-walled carbon nanotubes for sustainable production of the flavor ester geranyl propionate

In this study, geranyl propionate was enzymatically synthesized from geraniol and propionic acid using Candida rugosa lipase immobilized on acid functionalized multi-walled carbon nanotubes. The efficiency of the CRL-MWCNTs biocatalysts to catalyze the esterification production of geranyl propionate (solvent logP, alcohol:acid molar ratio and thermal stability) was compared with the free CRL for parameters. The use of CRL-MWCNTs in n-heptane (logP 4.0) and alcohol:acid molar ratio of 5:1 resulted in a 2-fold increased conversion frequency as compared to the free CRL for the production of geranyl propionate, in addition to a noteworthy 2-fold enhanced thermal stability.

Adsorption of Candida rugosa lipase onto alumina: Effect of surface charge

The impact of the surface charge of alumina support on the adsorption of Candida rugosa lipase has been investigated in terms of zeta potential of the adsorption partners. Lipase adhered onto alumina with similar efficiency under both repulsive and attractive electrostatic conditions, shifting the zeta potential of the support towards that of the enzyme. The behavior was explained by a heterogeneous distribution of the surface charge of the lipase molecule. Special emphasis in this study was placed on the effect of immobilization on enzyme kinetics and principal reasons for enzyme immobilization: improvement in stability and potential for reuse. The enzyme affinity was not altered by its adsorption onto alumina, while Vmax of the lipase decreased. Thermostability of adsorbed lipase was improved. Significant potential for reuse was found.

Adsorption of Candida rugosa lipase at water-polymer interface: The case of poly(dl)lactide

Insights into the interactions between biological macromolecules and polymeric surfaces are of great interest because of potential uses in developing biotechnologies. In this study we focused on the adsorption of a model lipolytic enzyme, Candida rugosa lipase (CRL), on poly-(d,l)-lactic acid (PDLLA) polymer with the aim to gain deeper insights into the interactions between the enzyme and the carrier. Such studies are of particular relevance in order to establish the optimal conditions for enzyme immobilization and its applications. We employed two different approaches; by analyzing the influence of adsorbed CRL molecules on the thermodynamic behavior of Langmuir films of PDLLA deposited at air–water interface, we gained interesting information on the molecular interactions between the protein and the polymer. Successively, by a systematic analysis of the adsorption of CRL on PDLLA nanoparticles, we showed that the adsorption of a model lipase, CRL, on PDLLA is described in terms of a Langmuir-type adsorption behavior. In this model, only monomolecular adsorption takes place (i.e. only a single layer of the protein adsorbs on the support) and the interactions between adsorbed molecules and surface are short ranged. Moreover, both the adsorption and desorption are activated processes, and the heat of adsorption (the difference between the activation energy for adsorption and desorption) is independent from the surface coverage of the adsorbing species. Finally, we obtained an estimate of the number of molecules of the protein adsorbed per surface unit on the particles, a parameter of a practical relevance for applications in biocatalysis, and a semi-quantitative estimate of the energies (heat of adsorption) involved in the adsorption process.

Effect of oxidation level of n+-type mesoporous silicon surface on the adsorption and the catalytic activity of Candida rugosa lipase

In this work, we present the synthesis and characterization of n +-type porous silicon (PSi) layers. Our final aim is the fabrication of a biosensor that exploits the semiconductive properties of this material. PSi wafers were used as a matrix for enzyme adsorption. These wafers, as a result of their porous nanostructure, had a high surface area (360 m 2/g) and pore size in the range 5–20 nm. The freshly prepared PSi was stabilized through controlled anodic oxidation. Two classes of samples differing for the level of oxidation were prepared. The first class was oxidized up to 2 V (LO-PSi), whereas the second class was oxidized up to 10 V (HO-PSi). Both samples were used for the adsorption of Candida rugosa lipase. A significantly higher loading was ascertained for LO-PSi (140 mg/g) compared to HO-PSi (47 mg/g). The different hydrophobic–hydrophilic balance of the PSi surfaces induced by the different oxidation voltage affects the physical interactions that address the adsorption process of the lipase. The higher loading achieved with the LO-PSi resulted in a higher activity of the immobilized biocatalyst but in a lower catalytic efficiency. The two biocatalysts showed an acceptable stability toward storage (pH 5 buffer solution at 5 °C) within 2 weeks.

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Lipase from Candida rugosa was immobilized on a β-cyclodextrin-based polymer by adsorption and subsequent cross-linking with epichlorohydrin (EP-CD). The ligand iminodiacetic acid (IDA) was then bonded with the cross-linked β-cyclodextrin (EP-CD-IDA). This affinity adsorbent was further chelated with Cu2 + for the purpose of binding affinity and stability. The properties of the immobilized lipase were assayed and compared with those of the free enzyme. Results showed that 266 µg protein with an activity of 17.85 U was bound per gram of matrix, giving 188% of the specific activity of the free enzyme and a total recovered activity of 79.7% under the optimum conditions. The pH and thermal stabilities of lipase were improved after immobilization on the β-cyclodextrin-based polymer (EP-CD-IDA-Cu2 +). In addition, experimental results indicated that the residual activity of the immobilized lipase was 50% after eight cycles of reuse.

Ethanol pretreatment effect and particle diameter issues on the adsorption of Candida rugosa lipase onto polypropylene powder

Lipase from Candida rugosa (CR) was adsorbed onto low-molecular-weight polypropylene powder (PP). Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) techniques, and conversion yield of CR/PP-mediated-ethyl oleate synthesis in solvent-free media, demonstrated lipase adsorption onto PP and its affinity towards biggest polypropylene particles (590–1180μm). An ethanol pretreatment was assayed in order to decrease the hydrophobic nature of PP. Long periods of ethanol pretreatment led to immobilised particles with different average size and associated activity. Molecular mechanics software packages were used to study the interaction between polypropylene and CR’s lid.