Support Material For Immobilization Research Articles

Modelling photoperiod in enhancing hydrogen production from Chlorella vulgaris sp. while bioremediating ammonium and organic pollutants in municipal wastewater

Municipal wastewater is ubiquitously laden with myriad pollutants discharged primarily from a combination of domestic and industrial activities. These heterogeneous pollutants are threating the natural environments when the traditional activated sludge system fails sporadically to reduce the pollutants' toxicities. Besides, the activated sludge system is very energy intensive, bringing conundrums for decarbonization. This research endeavoured to employ Chlorella vulgaris sp. In converting pollutants from municipal wastewater into hydrogen via alternate light and dark fermentative process. The microalgae in attached form onto 1 cm3 of polyurethane foam cubes were adopted in optimizing light intensity and photoperiod during the light exposure duration. The highest hydrogen production was recorded at 52 mL amidst the synergistic light intensity and photoperiod of 200 μmolm−2s−1 and 12:12 h (light:dark h), respectively. At this lighting condition, the removals of chemical oxygen demand (COD) and ammoniacal nitrogen were both achieved at about 80%. The sustainability of microalgal fermentative performances was verified in recyclability study using similar immobilization support material. There were negligible diminishments of hydrogen production as well as both COD and ammoniacal nitrogen removals after five cycles, heralding inconsequential microalgal cells’ washout from the polyurethane support when replacing the municipal wastewater medium at each cycle. The collected dataset was finally modelled into enhanced Monod equation aided by Python software tool of machine learning. The derived model was capable to predict the performances of microalgae to execute the fermentative process in producing hydrogen while subsisting municipal wastewater at arbitrary photoperiod. The enhanced model had a best fitting of R2 of 0.9857 as validated using an independent dataset. Concisely, the outcomes had contributed towards the advancement of municipal wastewater treatment via microalgal fermentative process in producing green hydrogen as a clean energy source to decarbonize the wastewater treatment facilities.

Support Materials of Organic and Inorganic Origin as Platforms for Horseradish Peroxidase Immobilization: Comparison Study for High Stability and Activity Recovery.

In the presented study, a variety of hybrid and single nanomaterials of various origins were tested as novel platforms for horseradish peroxidase immobilization. A thorough characterization was performed to establish the suitability of the support materials for immobilization, as well as the activity and stability retention of the biocatalysts, which were analyzed and discussed. The physicochemical characterization of the obtained systems proved successful enzyme deposition on all the presented materials. The immobilization of horseradish peroxidase on all the tested supports occurred with an efficiency above 70%. However, for multi-walled carbon nanotubes and hybrids made of chitosan, magnetic nanoparticles, and selenium ions, it reached up to 90%. For these materials, the immobilization yield exceeded 80%, resulting in high amounts of immobilized enzymes. The produced system showed the same optimal pH and temperature conditions as free enzymes; however, over a wider range of conditions, the immobilized enzymes showed activity of over 50%. Finally, a reusability study and storage stability tests showed that horseradish peroxidase immobilized on a hybrid made of chitosan, magnetic nanoparticles, and selenium ions retained around 80% of its initial activity after 10 repeated catalytic cycles and after 20 days of storage. Of all the tested materials, the most favorable for immobilization was the above-mentioned chitosan-based hybrid material. The selenium additive present in the discussed material gives it supplementary properties that increase the immobilization yield of the enzyme and improve enzyme stability. The obtained results confirm the applicability of these nanomaterials as useful platforms for enzyme immobilization in the contemplation of the structural stability of an enzyme and the high catalytic activity of fabricated biocatalysts.

Optimization of whole-cell bacterial bioreporter immobilization on electrospun cellulose acetate (CA) and polycaprolactone (PCL) fibers for arsenic detection.

Arsenic contamination is a critical global problem, and its widespread environmental detection is becoming a prominent issue. Herein, electrospun fibers of cellulose acetate (CA) and polycaprolactone (PCL) were successfully fabricated and used as the support material for immobilization of arsenic-sensing bacterial bioreporter for the first time. To date, no attempt has been made to immobilize fluorescent whole-cell bioreporter cells on electrospun fibers for arsenic detection. CA and PCL electrospun fibers were fabricated via traditional electrospinning technique and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and contact angle meter. Following immobilization of the bacterial bioreporter cells, the immobilized bacteria were also characterized by viability assay using AlamarBlue. The effects of growth phase and cell concentration on the fluorescence response of fiber-immobilized arsenic bioreporters to arsenic were also investigated. After immobilization of arsenic bioreporters on 10 wt% PCL fiber, 91% of bacterial cells remained viable, while this value was 55.4% for cells immobilized on 12.5 wt% CA fiber. Bioreporter cells in the exponential growth phase were shown to be more sensitive to arsenic compared to aged cells. While both the electropsun PCL- and CA-immobilized bioreporters successfully detected 50 and 100µg/L of arsenite (As (III)) concentrations, the PCL-immobilized bioreporter showed better fluorescence performance which should be investigated in future studies. This study helps to fill some gaps in the literature and demonstrates the potential for using electrospun fiber-immobilized arsenic whole-cell bioreporter for arsenic detection in water.

Ethanol production by immobilized Saccharomyces cerevisiae cells on 3D spheres designed by different lattice structure types

Natural or synthesized materials can be used for cell immobilization to enhance cell viability and productivity in fermentation processes (batch, fed-batch or continuous fermentations). 3D printing is one of the newest technologies to produce unique immobilization support materials. In this research, the selection strategy of 3D lattice structure type for unique immobilization materials, effect of different lattice structure types on cell immobilization in a shake flask experiments and optimization of ethanol production in a laboratory scale bioreactor with 3D spheres were studied. Firstly, 3D designs were compared to determine the best type of 3D spheres with a higher area:volume ratio for cell immobilization. Then shake flask experiments were performed and showed that W, 20 mm is the best 3D sphere combination for ethanol fermentation. Finally, over 37 g/L ethanol (ethanol yield ranged from 41.91% to 46.36%) was produced at all repeated batch cycles by using 100 g/L initial sugar with at least 82% sugar utilization capacity in a lab-scale bioreactor successfully. All results showed that 3D-printed materials could be used as immobilization agents for microorganisms by selecting the proper geometry, size and printing technology.

Electrospun aluminum silicate nanofibers as novel support material for immobilization of alcohol dehydrogenase

Ceramic materials with high surface area, large and open porosity are considered excellent supports for enzyme immobilization owing to their stability and reusability. The present study reports the electrospinning of aluminum silicate nanofiber supports from sol-gel precursors, the impact of different fabrication parameters on the microstructure of the nanofibers and their performance in enzyme immobilization. A change in nanofiber diameter and pore size of the aluminum silicate nanofibers was observed upon varying specific processing parameters, such as the sol-composition (precursor and polymer concentration), the electrospinning parameters and the subsequent heat treatment (calcination temperature). The enzyme, alcohol dehydrogenase (ADH), was immobilized on the aluminum silicate nanofibers by physical adsorption and covalent bonding. Activity retention of 17% and 42% was obtained after 12 d of storage and repeated reaction cycles for physically adsorbed and covalently bonded ADH, respectively. Overall, the immobilization of ADH on aluminum silicate nanofibers resulted in high enzyme loading and activity retention. However, as compared to covalent immobilization, a marked decrease in the enzyme activity during storage for physically adsorbed enzymes was observed, which was ascribed to leakage of the enzymes from the nanofibers. Such fibers can improve enzyme stability and promote a higher residual activity of the immobilized enzyme as compared to the free enzyme. The results shown in this study thus suggest that aluminum silicate nanofibers, with their high surface area, are promising support materials for the immobilization of enzymes.

Fumaric acid production using alternate fermentation mode by immobilized Rhizopus oryzae-a greener production strategy

The current work investigates the impact of using immobilized Rhizopus oryzae NRRL 1526 for bioproduction of fumaric acid using agro-industrial residues as feedstock. This use of agro-industrial residues, a renewable feedstock, for the production of bio-based platform chemical makes the process cost-competitive as well as greener by preventing the release of assimilable organic carbon to the environment, thereby reducing the generation of greenhouse gases. Immobilization of R. oryzae has been proposed previously to alleviate operational difficulties confronted during free mycelial fungal fermentation. To this effect, three synthetic refuse materials namely polystyrene foam, polyester sponge and polyurethane foam were investigated for their suitability towards fumaric acid bioproduction. Polystyrene foam was identified as the most suitable support material for immobilization as well as fumaric acid production. In addition to the considerable reduction in the lag-phase (from 48 to 24 h) the reduction in the size of the support material from cubes of 1 cm to beads of 0.1–0.3 cm led to a 42% improvement in fumaric acid production (27 g/L against 19 g/L). Growing the polystyrene foam bead immobilized R. oryzae on apple pomace ultrafiltration sludge as sole feedstock yielded a final fumaric acid titer of 7.9 g/L whereas free mycelial fermentation yielded 6.3 g/L. Moreover, upon operating the fermentation with intermittent feeding, a three-fold increase (1.7 g/L to 5.1 g/L) in fumaric acid production was obtained upon supplementation of the apple pomace sludge media with molasses, an agro-industrial residue, as feed.

Ferromagnetic nanoparticles synthesis and functionalization for laccase enzyme immobilization

Ferromagnetic nanomaterials can easily be separated from the reaction media by using external magnetic force. Nanoparticles are excellent supporting materials that provide large surface area with high mass transfer rate. Ferromagnetic nanoparticle considered as an ideal immobilization supporting materials of biocatalysts for easy and fast recovery. In this study, ferromagnetic iron oxide nanoparticles were synthesized and functionalized as immobilization support materials. Amino functionalization of nanoparticles was performed to improve thermal stability and enzymatic activity. XRD planes at 2θ confirmed the successful synthesis of ferromagnetic nanoparticles. FTIR spectrum used to identify amino functionalization of nanoparticles, and size and surface morphology were studied through transmission electron microscopy (TEM).

Developments in the Use of Lipase Transesterification for Biodiesel Production from Animal Fat Waste

Biodiesel constitutes an attractive source of energy because it is renewable, biodegradable, and non-polluting. Up to 20% biodiesel can be blended with fossil diesel and is being produced and used in many countries. Animal fat waste represents nearly 6% of total feedstock used to produce biodiesel through alkaline catalysis transesterification after its pretreatment. Lipase transesterification has some advantages such as the need of mild conditions, absence of pretreatment, no soap formation, simple downstream purification process and generation of high quality biodiesel. A few companies are using liquid lipase formulations and, in some cases, immobilized lipases for industrial biodiesel production, but the efficiency of the process can be further improved. Recent developments on immobilization support materials such as nanoparticles and magnetic nanomaterials have demonstrated high efficiency and potential for industrial applications. This manuscript reviews the latest advances on lipase transesterification and key operational variables for an efficient biodiesel production from animal fat waste.

Immobilization of Acidithiobacillus ferrooxidans-1333 on the Waste Ore Particles for the Continuous Oxidation of Ferrous Iron.

Background: The biooxidation of ferrous iron has a great potential for the regeneration of ferric iron, in operations such as bioleaching, bioremediation. Many natural inorganic materials were investigated for use as supports immobilizing Acidithiobacillus ferrooxidans. The waste chalcopyrite is another natural inorganic material of which particles are easy to prepare from the leached out ore heaps and the source is abundant.Objectives: The aim of this work is to investigate several characteristics of the particles of waste ore that determines possibility of use as supports for immobilization of Acidithiobacillus ferrooxidans in the packed-bed bioreactor.Materials and Methods: Acidithiobacillus ferrooxidans-1333 stored in Korean Centre for Culture Collection was used. The supports were prepared by sieving the particles of 5~30 mm in size out from the waste chalcopyrite ore heap. The cells were immobilized by the successive batch culture method and oxidation rate of the bioreactor was investigated in the continuous flow mode.Results: The cell density of Acidithiobacillus ferrooxidans-1333 immobilized on the particles of waste chalcopyrite was 2.71×108 cells g-1 and the highest oxidation rate of the packed-bed bioreactor was 3.65g.L-1.h-1. Oxidation rate of the bioreactor was less influenced by the concentration of ferrous and ferric iron in the input solution as well as by the aeration rate and dilution rate than other materials mentioned in other previous works.Conclusion: The waste chalcopyrite particle is efficient support material for immobilization of Acidithiobacillus ferrooxidans with comparable or superior characteristics to natural inorganic support materials reported before.

An Innovator Support Material for Tyrosinase Immobilization: Antimony-Doped Tin Oxide Thin Films (ATO-TF)

Tyrosinase (T3824, Sigma) enzymes were immobilized onto SnO2: Sb thin films (ATO-TF) which were synthesized in laboratory conditions by spray pyrolysis technique. Immobilization of tyrosinase onto SnO2: Sb thin film (ATO-TF) was confirmed by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The optimum pH of the immobilized tyrosinase (tyrosinase-ATO-TF) was 6.0, and the optimum temperature was found to be 30°C. In the presence of catechol substrate of immobilized enzymes, Km and Vmax values were determined as 0.34mM and 312.5U/cm2min, respectively. The thermal stabilities of the immobilized tyrosinase at 4°C and 30°C were investigated for 20, 40, and 60min. At these temperatures and time intervals, the immobilized tyrosinase was found to be highly stable. The pH stability of the immobilized tyrosinase enzymes was incubated for 24, 48, 72, and 96h at 4°C temperature. The enzyme activity was determined under optimum conditions, and the activity of the immobilized tyrosinase enzymes exhibited various values for the range of pH3.0-8.0. The storage stability of the immobilized tyrosinase enzymes at 4°C was investigated, and 45.72% of the initial activity was maintained at the end of the seventh day. Furthermore, the reusability of the immobilized tyrosinase enzymes has been examined. The immobilized tyrosinase enzymes can be used 3 times and survived their 50% of initial activity. The ATO-TF can be used as alternative support materials for the immobilization of tyrosinase enzymes.

Hemp Fibres as Novel Green Support Material for Immobilization of Acidithiobacillus ferrooxidans

The suitability of hemp fibres as green support material for immobilization of Acidithiobacillus ferrooxidans cells in ferrous iron bio-oxidation process was investigated. A series of experiments were carried out in shake flasks and bioreactor for both cell immobilization and iron bio-oxidation. In flask experiments, five successive batch colonization cycles resulted in 6-fold increase in ferrous iron bio-oxidation rate. Evaluation of immobilized cells activity through two approaches as wet and dry storage demonstrated the higher activity of wet stored bacteria than dry ones after a period of two months. The dry stored bacteria lost almost all their activities after eight weeks. Whereas, the activity of wet stored samples was 30% at the same time. In bioreactor experiments, use of a packed-bed bioreactor with hemp fibres, the maximum ferrous iron bio-oxidation rate of 2.46 kg m-3 h-1 was obtained at dilution rate of 3.97 h-1, and retention time of 0.25 h. Our experimental results could pave a new platform for the application of hemp fibre as an inexpensive and environmentally friendly support material in bacterial cell immobilization, especially in ferrous iron bio-oxidation process using acidophilic bacteria.

Functionalized Poplar Powder as a Support Material for Immobilization of Enoate Reductase and a Cofactor Regeneration System.

In this study, functionalized poplar powder (FPP) was used as a support material for the immobilization of enoate reductase (ER) and glucose-6-phosphate dehydrogenase (GDH) by covalent binding. Under optimal conditions, the immobilization efficiency of ER-FPP and GDH-FPP was 95.1% and 84.7%, and the activity recovery of ER and GDH was 47.5% and 37.8%, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis indicated that FPP was a suitable carrier for enzyme immobilization. ER-FPP and GDH-FPP exhibit excellent thermal stabilities and superior reusability. Especially, ER-FPP and GDH-FPP enable the continuous conversion of 4-(4-Methoxyphenyl)-3-buten-2-one with NAD+ recycling. While the immobilization strategies established here were simple and inexpensive, they exploited a new method for the immobilization and application of ER and its cofactor recycling system.

Yeast Immobilization on Peanut Hulls for Potential Application in Beer Fermentation

The potential of using peanut hulls as support material for immobilization of yeast cells during beer fermentation was evaluated. After treatment of peanut hulls with 0.5% (w/v) NaOH, FTIR analysis revealed an important change on its chemical composition. For instance, the proportion of lignin decreased and as a result the adsorption of yeast cells onto the support material during fermentation was favoured. Cell adhesion onto the conditioned support in 8° Brix laboratory malt wort as fermentation medium was evaluated, observing a maximal cell adhesion (2.56×108 cells/g of dried support) at 20.5 h of cultivation. Evaluations of the performance of the biocatalyst in fermentations at 15±0.5°C in 14° Brix laboratory malt wort indicated a proper stability in terms of physical integrity (confirmed by SEM observation) and improved fermentation kinetics. The fermentation time was shortened to approximately four days and the rates of reducing sugar consumption and ethanol production were improved when compared to fermentations carried out with free suspended cells. These results show a promising potential of peanut hulls as support material in beer fermentation.

Immobilization of Peroxidase on Functionalized MWCNTs-Buckypaper/Polyvinyl alcohol Nanocomposite Membrane

Surface modified Multi-walled carbon nanotubes (MWCNTs) Buckypaper/Polyvinyl Alcohol (BP/PVA) composite membrane was synthesized and utilized as support material for immobilization of Jicama peroxidase (JP). JP was successfully immobilized on the BP/PVA membrane via covalent bonding by using glutaraldehyde. The immobilization efficiency was optimized using response surface methodology (RSM) with the face-centered central composite design (FCCCD) model. The optimum enzyme immobilization efficiency was achieved at pH 6, with initial enzyme loading of 0.13 U/mL and immobilization time of 130 min. The results of BP/PVA membrane showed excellent performance in immobilization of JP with high enzyme loading of 217 mg/g and immobilization efficiency of 81.74%. The immobilized system exhibited significantly improved operational stability under various parameters, such as pH, temperature, thermal and storage stabilities when compared with free enzyme. The effective binding of peroxidase on the surface of the BP/PVA membrane was evaluated and confirmed by Field emission scanning electron microscopy (FESEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). This work reports the characterization results and performances of the surface modified BP/PVA membrane for peroxidase immobilization. The superior properties of JP-immobilized BP/PVA membrane make it promising new-generation nanomaterials for industrial applications.

Chicken Feather Derived Novel Support Material for Immobilization of Laccase and Its Application in Oxidation of Veratryl Alcohol

Application of a biocatalyst at an industrial scale primarily depends on its intrinsic properties, the nature of the support materials, and the scalability of the catalyst. Support materials play a...

Methacrylated Chitosan Based UV Curable Support for Enzyme Immobilization

UV curing is simple, fast and effective procedure for enzyme immobilization with minimized enzymatic activity. UV-curable methacrylated chitosan is here proposed as a support material for immobilization of lipase. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM). Both covalently (CIL) and physically (PIL) immobilized enzyme is analyzed in terms of enzymatic activity as a function of reusability, pH, storage, as well as stability under various experimental conditions. The recovery of activity of lipases immobilized onto a photo-crosslinked polymer network was 82.0% and 70.0% for CIL and PIL, respectively. The optimum pH value for the free lipase was at pH 6.0. The optimum pH of the both CIL and PIL was shifted to pH 7.0. Immobilization increased the thermostability of the lipase from 50 oC to 62 oC. The free enzyme lost all its activity within 15 days. Repeated batch experiments show that about 61% of the enzyme activity of CIL and 41% of PIL was retained after 8 cycles.

Magnetic Ganoderma lucidum spore microspheres: A novel material to immobilize CotA multicopper oxidase for dye decolorization

In this study, hollow microspheres were obtained from Ganoderma lucidum spores. Then the hollow microspheres were loaded with Fe3O4 nanoparticles to prepare novel magnetic spore microspheres. TEM images and X-ray diffractometry demonstrated that the Fe3O4 nanoparticles were incorporated throughout the spore microsphere. CotA multicopper oxidase was chosen as biomacromolecule to study the loading ability of the magnetic spore microspheres. The combination of the CotA enzyme with the microsphere was observed by laser scanning confocal microscope. The loaded amount of CotA on the microspheres was 75mg/g when the CotA concentration was 1.2mg/mL and the activity recovery of the immobilized CotA was 81%. The magnetic microspheres loaded with CotA, which can be easily and quickly recovered by an external magnetic field, were used for dye decolorization. After 1h decolorization, 99% of the indigo carmine has been removed by 10mg microspheres. In addition, the immobilized CotA retained 75% of activity after 10 consecutive cycles, which indicated that the magnetic spore microspheres are good support material for immobilization of the enzyme.

Study of acyl migration during enzymatic interesterification of liquid and fully hydrogenated soybean oil

Lipase-catalyzed interesterification has emerged as an attractive process to obtain plastic fats because of its numerous advantages compared to the chemical reaction. The use of sn-1,3 specific lipases adds an even more interesting feature to this process, which is related to the possibility of maintaining the sn-2 fatty acid composition of natural substrates unaltered. The pursuit of this characteristic in interesterified products by sn-1,3 specific lipases could be threatened by a chemical reaction, the acyl migration whithin mono- and diacylglycerols. The aim of this study was to evaluate the occurrence of this undesired reaction in a soybean oil:fully hydrogenated soybean oil enzymatic interesterified blend. Once acyl migration was confirmed to occur, the influence of different reaction parameters -namely enzyme type and concentration, substrate ratio, and addition of hexane and temperature effect- was studied. Lipozyme TL IM demonstrated an enhancer acyl migration effect compared to Lipozyme RM IM, effect that was hypothesized to be correlated with the immobilization support material of the former (silica gel). Acyl migration was also promoted by the increase of biocatalyst concentration in reaction media. On the contrary, the presence of hexane, together with a decrease in temperature reaction, reduced its occurrence. A temperature effect analysis performed in solvent reaction media demonstrated its promoter effect on acyl migration.

Two-stage repeated-batch fermentation of immobilized Clostridium beijerinckii on oil palm fronds for solvents production

In this study, palm tree wastes including oil palm shells, palm press fibers, empty fruit bunches and oil palm fronds were evaluated as possible eco-friendly support materials for immobilization of solvent-producing Clostridium beijerinckii. Among support materials tested, oil palm fronds are the most suitable support materials for cell immobilization and repeated-batch production of solvents by non-growing cells incubated in nitrogen-free medium. The non-growing immobilized cells on 7% (w/v) oil palm fronds produced the highest solvent yield of 12.2g/L in the 1st batch. However, in the 2nd and 3rd batches the solvent production was reduced to 9.01g/L and 4.95g/L, respectively. Two-stage repeated-batch fermentation in which immobilized cells were re-incubated in nitrogen-rich medium (Stage I) before being re-used in nitrogen-free medium (Stage II), were then attempted. The solvents produced by this strategy remained >80% in the 3rd cycle and >55% in the 4th cycle. The total solvent yields in the 1st, 2nd, 3rd and 4th cycles were as high as 31.5, 30.6, 25.3 and 17.5g/L, respectively. This study has shown that lignocellulosic palm tree wastes can be used as low-cost support materials for immobilization of clostridia and the solvent productivity can be improved by two-stage repeated-batch fermentation.

A fluorescence spectroscopy assay for real-time monitoring of enzyme immobilization into mesoporous silica particles

Mesoporous silica particles are used as support material for immobilization of enzymes. Here we investigated a fluorescence-based assay for real-time monitoring of the immobilization of lipase, bovine serum albumin, and glucose oxidase into micrometer-sized mesoporous silica particles. The proteins are labeled with the dye epicocconone, and the interaction with the particles is observed as an increase in emission intensity of the protein–dye conjugates that can be quantified if correcting for a comparatively slow photobleaching. The immobilization occurs in tens of minutes to hours depending on particle concentration and type of protein. In the limit of excess particles over proteins, the formation of the particle–protein complexes can be described by a single exponential growth for all three investigated proteins, and the fitted pseudo-first-order rate constant increases linearly with particle concentration for each protein type. The derived second-order rate constant k varies with the protein hydrodynamic radius according to k∼RH−4.70±0.01, indicating that the rate-limiting step at high particle concentrations is not the diffusional encounter between proteins and particles but rather the entry into the pores, consistent with the hydrodynamic radii of the three proteins being smaller but comparable to the pore radius of the particles.