Preparation of immobilized lipase by modified polyacrylonitrile hollow membrane using nitrile-click chemistry

Artificial antibody-antigen-directed immobilization of lipase for consecutive catalytic synthesis of ester: Benzyl acetate case study

A strategy based on artificial antibody-antigen recognition was proposed for the specific directed immobilization of lipase. The artificial antibody was synthesized using catechol as a template, α-methacrylic acid as a functional monomer, and Fe3O4 as the matrix material. Lipase was modified with 3,4-dihydroxybenzaldehyde as an artificial antigen. The artificial antibody can specifically recognize catechol fragment in the enzyme structure to achieve the immobilization of lipase. The immobilization amount, yield, specific activity, and immobilized enzyme activity were 13.2 ± 0.2 mg/g, 78.9 ± 0.4 %, 7.9 ± 0.2 U/mgprotein, and 104.6 ± 1.7 U/gcarrier, respectively. Moreover, the immobilized lipase exhibited strong reusability and regeneration ability. Additionally, the immobilized lipase successfully catalyzed the synthesis of benzyl acetate and demonstrated robust continuous catalytic activity. These results fully demonstrate the feasibility of the proposed artificial antibody-antigen-directed immobilization of lipase.

Lipolytic production from solid-state fermentation of the filamentous fungus Penicillium polonicum and its applicability as biocatalyst in the synthesis of ethyl oleate

Lipases represent versatile biocatalysts extensively employed in transesterification reactions for ester production. Ethyl oleate holds significance in biodiesel production, serving as a sustainable alternative to petroleum-derived diesel. In this study, our goal was to prospect lipase and assess its efficacy as a biocatalyst for ethyl oleate synthesis. For quantitative analysis, a base medium supplemented with Rhodamine B, olive oil, and Tween 80 was used. Solid-state fermentation utilized crambe seeds of varying particle sizes and humidity levels as substrates. In the synthesis of ethyl oleate, molar ratios of 1:3, 1:6, and 1:9, along with a total enzymatic activity of 60 U in n-heptane, were utilized at temperatures of 30 °C, 37 °C, and 44 °C. Reactions were conducted in a shaker at 200 rpm for 60 min. As a result, we first identified Penicillium polonicum and employed the method of solid-state fermentation using crambe seeds as a substrate to produce lipase. Our findings revealed heightened lipolytic activity (22.5 Ug-1) after 96 h of fermentation using crambe cake as the substrate. Optimal results were achieved with crambe seeds at a granulometry of 0.6 mm and a fermentation medium humidity of 60%. Additionally, electron microscopy suggested the immobilization of lipase in the substrate, enabling enzyme reuse for up to 4 cycles with 100% enzymatic activity. Subsequently, we conducted applicability tests of biocatalysts for ethyl oleate synthesis, optimizing parameters such as the acid/alcohol molar ratio, temperature, and reaction time. We attained 100% conversion within 30 min at 37 °C, and our results indicated that the molar ratio proportion did not significantly influence the outcome. These findings provide a methodological alternative for the utilization of biocatalysts in ethyl oleate synthesis.

Design of composite nanosupports and applications thereof in enzyme immobilization: A review

Enzyme immobilization techniques have developed dramatically over the past several decades. Support materials are key in shaping the function of a specific immobilized enzyme. Although they have large specific surface areas and functional active sites, single-component nanomaterials and their surface chemical modification derivatives struggle to meet increasing demand. Thus, composite materials, compounds of two or more materials, have been developed and applied in efficient immobilization through advances in materials science. More methods have been developed and employed to design composite nanomaterials in recent years. These novel composite nanomaterials often show superior physical, chemical, and biological performance as supports in enzyme immobilization, among other applications. In this review, immobilization techniques and their supports are stated first and methods to design and fabricate composite nanomaterials as nanosupports are also shown in the following section. Applications of composite nanosupports in laccase immobilization are discussed as models in the later sections of the paper. This review is intended to help readers gain insight into the design principles of composite nanomaterials for immobilization supports.

Enzymatic membrane reactor in xylose bioconversion with simultaneous cofactor regeneration

In this study, we present the concept of co-immobilization of xylose dehydrogenase and alcohol dehydrogenase from Saccharomyces cerevisiae on an XN45 nanofiltration membrane for application in the process of xylose bioconversion to xylonic acid with simultaneous cofactor regeneration and membrane separation of reaction products. During the research, the effectiveness of the co-immobilization of enzymes was confirmed, and changes in the properties of the membrane after the processes were determined. Using the obtained biocatalytic system it was possible to obtain 99% xylonic acid production efficiency under optimal conditions, which were 5 mM xylose, 5 mM formaldehyde, ratio of NAD+:NADH 1:1, and 60 min of reaction. Additionally, the co-immobilization of enzymes made it possible to improve stability of the co-immobilized enzymes and to carry out xylose conversion in six consecutive cycles and after 7 days of storage at 4 °C with over 90% efficiency. The presented data confirm the effectiveness of the co-immobilization, improvement of the stability and reusability of the biocatalysts, and show that the obtained enzymatic system is promising for use in xylose bioconversion and simultaneous regeneration of nicotinamide cofactor.

Microwave pyrolysis coupled with conventional pre-pyrolysis of the stalk for syngas and biochar

The study presented a novel approach microwave pyrolysis coupled conventional pre-pyrolysis (MCCP) to dispose of the stalk for syngas and biochar. Impacts of preheating temperature (250 ∼ 450 °C) on pyrolysis property and products characteristics were investigated. Compared with microwave-assisted pyrolysis (MAP), the initial time for rapid temperature ramp in MCCP was distinctly advanced from 124 s to within 20 s; the biochar yields significantly increased from 24.19% to 33.24%, and the H₂ content of syngas in the second stage reached up to 64.65%. The biochar from MCCP had higher carbon content (greater than 70%), carbon retention (greater than 50%), and BET surface area (141.69 m²/g) than MAP. A high degree of aromatization and complete carbon skeleton structure was observed in the biochar from MCCP. Finally, a mobile application system based on MCCP was proposed, increasing the energy efficiency from 13.5 ∼ 27% (MAP) to 58.5 ∼ 76.5%.

Polyacrylonitrile Derived Robust and Flexible Poly(Ionic Liquid)s Nanofiber Membrane as Catalyst Supporter

Poly(ionic liquid)s nanofiber (PIL NF) membrane was derived from polyacrylonitrile by converting its cyano groups to imidazoline moieties via cyclization with ethylenediamine, followed by quaternization with 1-bromobutane. The novel PIL NF is further decorated with photocatalyst phosphotungstic acid PW12 via anion exchanging to give PW-PIL. The degradation rate of the novel supported photocatalyst towards methyl orange irradiated under visible light was found to be 98%. In addition, the nanofiber membrane morphology is beneficial for easy recycling, and 98% of original degradation rate was maintained after 5 cycles of photocatalysis degradation. This robust, efficient, and recyclable material offers a new approach for serving as catalyst supporter. The photocatalyst PW-PIL is reported for the first time. The inexpensive functional membrane is used to exploit the sun as a cheap and clean source of light.

An effective immobilization of β-glucosidases by partly cross-linking enzyme aggregates

Enzyme immobilization provides ideal operating conditions for enzymes stabilization and sustainable recycling. In this work, as a kind of clay material, montmorillonite (MTL) was chosen for immobilizing the β-glucosidase extracted from Agrocybe aegirit. The immobilized β-glucosidase via partly cross-linking enzyme aggregates (pCLEAs) formed by self-catalysis provided biocatalysts with satisfactory thermal and pH stability. Compared to the glutaraldehyde cross-linked, the immobilized β-glucosidase (β-G-pCLEAs@MTL) exhibited significantly higher immobilization efficiency (IE) and immobilization yield (IY), which were 80.6% and 76.9%, respectively. The β-G-pCLEAs@MTL also showed better stability and preferable reusability. And the activity of the β-G-pCLEAs@MTL remained 85.0% after 5 cycles and 74.7% after 10 cycles. Therefore, the method based on the pre- crosslinking to form pCLEAs and after-immobilization can effectively improve IY and IE. In addition, MTL seems to be a good alternative carrier to immobilize other enzymes for industrial application.

A Perspective Review on the Application of Polyacrylonitrile-Based Supports for Laccase Immobilization

The use of laccases applied in bioremediation processes has been increasingly studied, given the urgent need to overcome the environmental problems caused by emerging contaminants. It is known that immobilized enzymes have better operational stability under reaction conditions, allowing for greater applicability. However, given the lack of commercially available immobilized laccases, the search for immobilization materials and methods continues to gain effort. The use of polyacrylonitrile (PAN) to immobilize enzymes has been investigated since it is a low-cost material and can be modified and functionalized to well interact with the enzyme. This polymer can be used with different morphologies such as fibers, beads, and core-shell, presenting as an easily applicable alternative. This review presents the missing link between polymer and enzyme through an overview of PAN's current use as support for laccase immobilization and polymer functionalization methods, considering the importance of immobilized laccases in several industrial sectors.

Immobilization of Enzymes by Polymeric Materials

Enzymes are the highly efficient biocatalyst in modern biotechnological industries. Due to the fragile property exposed to the external stimulus, the application of enzymes is highly limited. The immobilized enzyme by polymer has become a research hotspot to empower enzymes with more extraordinary properties and broader usage. Compared with free enzyme, polymer immobilized enzymes improve thermal and operational stability in harsh environments, such as extreme pH, temperature and concentration. Furthermore, good reusability is also highly expected. The first part of this study reviews the three primary immobilization methods: physical adsorption, covalent binding and entrapment, with their advantages and drawbacks. The second part of this paper includes some polymer applications and their derivatives in the immobilization of enzymes.

Effect of applied voltage on membrane fouling in the amplifying anaerobic electrochemical membrane bioreactor for long-term operation

A novel and amplifying anaerobic electrochemical membrane bioreactor (AnEMBR, R2) was constructed and operated for a long time (204 days) with synthetic glucose solution having an average chemical oxygen demand (COD) of 315 mg L⁻¹, at different applied voltages and room temperatures. More than twice sodium bicarbonate was added for maintaining a pH of around 6.7 in the supernatant of the reactor R2, close to that of a control reactor called anaerobic membrane bioreactor (AnMBR, R1), after 138 days. And the transmembrane pressure (TMP) for the R2 system was only 0.534 bar at the end of operation and 0.615 bar for the R1 system. Although the electrostatic repulsion force contributed to pushing away the pollutants (proteins, polysaccharose and inorganic salt deposits, and so on), more microorganisms adsorbed and accumulated on the membrane surface after the whole operation, which might result in a rapid increase in membrane filtration resistance in the long-term operation. There were much more exoelectrogenic bacteria, mainly Betaproteobacteria, Deltaproteobacteria and Grammaproteobacteria, on the cathode and the dominant methanogen Methanothrix content on the cathode was three times higher than the AnMBR. The study provides an important theoretical foundation for the application of AnEMBR technology in the treatment of low organic strength wastewater.

A novel and amplifying anaerobic electrochemical membrane bioreactor was constructed and operated for a long time (204 days) with synthetic glucose solution having an average chemical oxygen demand (COD) of 315 mg L⁻¹, at different applied voltages and room temperatures.

Enzyme catalysis coupled with artificial membranes towards process intensification in biorefinery- a review

In this review, for the first time, the conjugation of the major types of enzymes used in biorefineries and the membrane processes to develop different configurations of MBRs, was analyzedfor the production of biofuels, phytotherapics and food ingredients. In particular, the aim is to critically review all the works related to the application of MBR in biorefinery, highlighting the advantages and the main drawbacks which can interfere with the development of this system at industrial scale. Alternatives strategies to overcome main limits will be also described in the different application fields, such as the use of biofunctionalized magnetic nanoparticles associated with membrane processes for enzyme re-use and membrane cleaning or the membrane fouling control by the use of integrated membrane process associated with MBR.

Alginate modification via click chemistry for biomedical applications

Alginate biopolymers are characterized by favorable properties, of biocompatibility, degradability, and non-toxicity. However, the poor stability properties of alginate have limited its suitability for diverse applications. Recently, click chemistry has generated significant research interest due to its high reaction efficiency, high selectivity for a single product, harmless byproducts, and processing simplicity. Alginate modified using click chemistry enables the production of alginate derivatives with enhanced physical and chemical properties. Herein, we review the employment of click chemistry in the development of alginate-based materials or systems. Various click chemistries were highlighted, including azide and alkyne cycloaddition (e.g. Copper-(I)-catalyzed azide-alkyne cycloaddition (CuAAC), Strain-promoted alkyne-azide cycloaddition (SPAAC)), Diels-Alder reaction (Inverse electron demand Diels-Alder (IEDDA) cycloaddition, Tetrazine-norbornene Diels-Alder reactions), Thiol-ene/yne addition (Free-radical thiol-ene addition click reactions, Thiol-Michael addition click reactions, Thiol-yne addition click reaction), Oxime based click reactions, and other click reactions. Alginate functionalized with click chemistry and its properties were also discussed. The present study shows that click chemistry may be employed in modifying the mechanical strength, biochemical/biological properties of alginate-based materials. Finally, the applications of alginate-based materials in wound dressing, drug delivery, protein delivery, tissue regeneration, and 3D bioprinting were described and the future perspectives of alginates modified with click chemistry, are subsequently presented. This review provides new insights for readers to design structures and expand applications of alginate using click chemistry reactions in a detailed and more rational manner.

Exogenous enzyme amendment accelerates maturity and changes microflora succession in horse and wildlife animal manure co-composting

Composting has been a rational method to dispose of horse or wildlife animal manures, especially in the developed cities with horse clubs and wildlife parks. However, few studies have focused on the mechanism and improvement methods for composting the horse or wildlife animal manures. In this study, we investigated the effect of exogenous compound enzymes on thermophilic composting, which could potentially support the management of horse and wildlife animal manures. With the presence of exogenous enzymes, the duration of high temperature (> 60 °C) was significantly prolonged (p < 0.05), and the germination index was significantly improved (p < 0.05). More-efficient improvement of composting maturity was associated with the addition of that exogenous enzyme that might influence microflora succession and the interaction among microorganic communities, especially fungal, during the composting process. Furthermore, redundancy and canonical correspondence analyses indicated that the C/N ratio, temperature, and germination index were significant variations to influence bacterial communities (p < 0.05). The dominant Flavobacterium, Thermopolyspora, Thermomonospora, and Chaetomium and Saccobolus could play an essential role in carbohydrate and phytotoxin degradation, while Thermobispora and norank_f_Limnochordaceae could lead to temperature rising.

Chemical waste and allied products

This paper reviews the related literature reported in 2019 about various types of wastewaters associated with chemical and allied products. The subjects comprise wastewaters produced from various activities in agricultural, chemical, dye, petrochemical, and pharmaceutical. PRACTITIONER POINTS: Bioflocculant chitosan was used for sludge dewatering and the treatment of water and wastewater, and polishing of sanitary landfill leachate. Alkaline lignin-based flocculants were used to achieve excellent color removal for paper mill sludge. Powdered activated coke was used to remove COD (chemical oxygen demand) from chemical industry wastewater effluents.

Immobilization of Aspergillus niger lipase onto a novel macroporous acrylic resin: Stable and recyclable biocatalysis for deacidification of high-acid soy sauce residue oil

Deacidification of high-acid soy sauce residue (SSR) oil is crucial to utilization of SSR oil. Aspergillus niger lipase (ANL) has been widely applied for such purpose while its immobilization still has large room for improvement. ANL was immobilized onto six different macroporous acrylic resins, accounting the effect of the different textural properties of resins on stability and their potential for application in enzymatic deacidification. The resin MARE with lower porosity, higher bulk density, and medium hydrophobicity, was chosen as the best carrier for the best thermostability and reusability. ANL-MARE is a promising catalyst than Novozym 40086, which not only exhibited higher deacidification activity and good thermostability, but also was continuously reused for 15 cycles and efficiently catalyzed from high-acid SSR oil into diacylglycerol-enriched oil. Therefore, immobilized ANL was a novel, low-cost and recyclable biocatalyst that could be used as a good alternative to higher-cost commercial lipases in industrial applications.

Research on the aerobic granular sludge under alkalinity in sequencing batch reactors: Removal efficiency, metagenomic and key microbes

Effects of additional alkalinity on the performance of aerobic granular sludge (AGS) in sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) were evaluated. Results showed that COD and ammonia-N (NH₄⁺-N) were slightly stimulated and remained high and stable with the increase of alkalinity up to 750 mg/L, while denitrification was boosted and total inorganic nitrogen (TIN) removal efficiency increased from 60.46% to 98.62% with an additional alkalinity of 750 mg/L. However, total phosphorus (TP) removal stayed unaffected and efficient. Illumina MiSeq sequencing revealed that microbial diversity and richness shifted mostly with 500 mg/L exterior alkalinity addition. Additional alkalinity altered the bacterial compositions within aerobic granules at various levels and the enrichment of Thiothrix and Acinetobacter was accounted for the promotion of COD and TIN removal.

Anti-oil-fouling hydrophobic-superoleophobic composite membranes for robust membrane distillation performance

As a promising thermally driven separation process, membrane distillation (MD) is capable of treating challenging wastewaters. However, the traditional hydrophobic membranes are vulnerable to fouling by non-polar contaminants owing to the strong hydrophobic-hydrophobic interactions. To address this problem, we developed novel anti-oil-fouling MD membranes in this study. The composite membranes with asymmetric wettability were fabricated through electrospinning polyacrylonitrile (PAN) fibrous coating on a hydrophobic polytetrafluoroethylene (PTFE) membrane, followed by hydrolyzing the PAN coating with ethylenediamine (EDA) and NaOH, respectively. These two composite membranes exhibited excellent underwater superoleophobicity, with the underwater oil contact angle >150°, which can be attributed to the fibrous and re-entrant surface structure and the optimized surface hydrophilicity of the electrospun coating. During MD process using saline and oily emulsion as feed, the composite membranes presented robust anti-oil-fouling performance, indicating by stable permeate flux and salt rejection. A novel oil-droplet adhesion force probe was introduced to quasi-quantitatively elucidate oil-membrane interaction and evaluate membrane fouling propensity, the force spectroscopy indicated that the fabricated composite membranes had fairly less attractive to crude oil compared with the PTFE membrane. Our research results suggest that the novel composite membranes with asymmetric wettability were competent to serve as an anti-oil-fouling MD membrane for desalinating challenging saline and oily wastewaters.

Novozym 435: the “perfect” lipase immobilized biocatalyst?

Novozym 435 (N435) is a commercially available immobilized lipase produced by Novozymes with its advantages and drawbacks.

Polyamine-induced tannic acid co-deposition on magnetic nanoparticles for enzyme immobilization and efficient biodiesel production catalysed by an immobilized enzyme under an alternating magnetic field

In this study, we report facile, rapid and stable polyamine TEPA-induced tannic acid (TA) co-deposition system-functionalized magnetic nanoparticles, which may provide an improved nanoplatform for enzyme immobilization.