Immobilization of phenol degrader pseudomonas sp in repeated batch culture using bioceramic and sponge as support materials

The performance of two types of inert support, namely bioceramic and sponge to immobilize a locally isolated phenol degrader Pseudomonas sp. in a packed column was investigated in repeated batch culture. Prior to this, our study indicated that immobilization had doubled the tolerance limit of the cells towards phenol from 1000 ppm (in the suspended culture), to 2000 ppm. For the same volume, the bioceramic managed to trap bacterial cells 1.8 times greater than the sponge did. As a result, it was able to remove 100% of 1000 ppm 600–ml phenol fed at a rate of 2.5 ml/min within 24 hours, and the phenol removal capacity was sustained in the next six consecutive batches. Cells entrapped in sponge however, managed to remove around 90% phenol in five batches. Despite lower performance, at large scales, the use of sponge for cell entrapment offers some merits such as lightness, and easily available at cheaper cost

Green biodiesel production: a review on feedstock, catalyst, monolithic reactor, and supercritical fluid technology

The advancement of alternative energy is primarily catalyzed by the negative environmental impacts and energy depletion caused by the excessive usage of fossil fuels. Biodiesel has emerged as a promising substitute to petrodiesel because it is biodegradable, less toxic, and reduces greenhouse gas emission. Apart from that, biodiesel can be used as blending component or direct replacements for diesel fuel in automotive engines. A diverse range of methods have been reported for the conversion of renewable feedstocks (vegetable oil or animal fat) into biodiesel with transesterification being the most preferred method. Nevertheless, the cost of producing biodiesel is higher compared to fossil fuel, thus impeding its commercialization potentials. The limited source of reliable feedstock and the underdeveloped biodiesel production route have prevented the full-scale commercialization of biodiesel in many parts of the world. In a recent development, a new technology that incorporates monoliths as support matrices for enzyme immobilization in supercritical carbon dioxide (SC-CO2) for continuous biodiesel production has been proposed to solve the problem. The potential of SC-CO2 system to be applied in enzymatic reactors is not well documented and hence the purpose of this review is to highlight the previous studies conducted as well as the future direction of this technology

Interfacial biocatalytic performance of nanofiber-supported β-galactosidase for production of galacto-oligosaccharides

Molecular distribution, structural conformation and catalytic activity at the interface between enzyme and its immobilising support are vital in the enzymatic reactions for producing bioproducts. In this study, a nanobiocatalyst assembly, β-galactosidase immobilized on chemically modified electrospun polystyrene nanofibers (PSNF), was synthesized for converting lactose into galacto-oligosaccharides (GOS). Characterization results using scanning electron microscopy (SEM) and fluorescence analysis of fluorescein isothiocyanat (FITC) labelled β-galactosidase revealed homogenous enzyme immobilization, thin layer structural conformation and biochemical functionalities of the nanobiocatalyst assembly. The β-galactosidase/PSNF assembly displayed enhanced enzyme catalytic performance at a residence time of around 1 min in a disc-stacked column reactor. A GOS yield of 41% and a lactose conversion of 88% was achieved at the initial lactose concentration of 300 g/L at this residence time. This system provided a controllable contact time of products and substrates on the nanofiber surface and could be used for products which are sensitive to the duration of nanobiocatalysis

Melt blown polypropylene nanofiber template for homogenous pore channels monoliths

Monoliths are an important technology for filtration, liquid chromatography, and protein purification. A template commonly uses to produce porous monolith. However, it is a challenge to produce a monolith with a homogenous porous structure due to the arrangements of pores within the monolith are often uneven and sometimes closed, causing pressure to accumulate and increase within the monolith which reduce the efficiency of the monoliths. Therefore, an appropriate template is needed to produce a monolith with homogenous porous structure. Nanofiber is a potential alternative as a template due to its high porosity and interconnectivity. Therefore, this research aimed to investigate the potential of polypropylene melt blown nanofiber fabricated at various operating condition to fabricate monolith by assessing the monolith morphology. Nanofibers templates were produced using a melt blowing technique at various motor speeds, air pressures, and die-to-collector distance (DCD) between 30 and 50 Hz, 0.30 and 0.50 Mpa, and 20 and 50 cm respectively, design by Response Surface Methodology. The nanofibers were characterized for its morphology and melting point using scanning electron microscope (SEM) and molten point analysis instrument respectively. The findings show that the polypropylene nanofiber diameter was in the range of 3.58 to 11.00 x 103 nm. Meanwhile, melting point obtained were in the range of 121.0 to 128.8 °C. Subsequently macropores monoliths were successfully fabricated at 0.45 Mpa air pressure, 40 Hz motor speed and 60.23 cm die-to-collector distance. It can be concluded that, melt blown polypropylene nanofiber can be potentially applied as a template for monolith fabrication

Production polystyrene micro-emulsion as template for monolith synthesis

Monolith have received much attention as high-performance chromatographic matrices due to its convective mass transfer and interconnected porous structure. Biodegradable polymers, free radicals and cross-linkers are among the templates used to form pore structure. However, poor heat dissipation and uneven pore size distribution across monolith remain as a key challenge in monolith fabrication. Therefore, this study aims to synthesize and characterize polystyrene micro-emulsion as template for monolith. The operating conditions for the synthesis of the polymeric micro-emulsion, that includes polymer concentration (14 - 35 wt %), surfactant concentration (1 - 9 wt %), temperature (30 - 70oC) and stirring rate (500 - 1000 rpm), were designed using Response Surface Methodology (RSM). The characterizations of resulting particles were observed using Scanning Electron Microscopy (SEM) and Inverted Microscope. The sizes of the particles were determined within range of 5.9 - 11.7 µm. Out of the 30 tested samples with different operating conditions, observation under the inverted microscope indicated homogenous particles of polystyrene microemulsion while some forming aggregations. Sample that was synthesized using 21 wt% polymer, 3 wt% surfactant, stirring rate at 875 rpm and heated at 40 oC resulted homogenous particles with particle diameter ranging from 7.92 µm to 8.80 µm. Good particle homogeneity was also obtained at a higher polymer concentration (35 wt %) using similar surfactant concentration and operating temperature at slower stirring rate (625 rpm). Samples aggregation were observed when using 35 wt % polymer, 7 wt % surfactant heated at 50oC at 750 rpm as well as sample under parameter of 25 wt% polymer wt % surfactant for 60oC stirring at 875 rpm. The findings of the study provide useful insights on the feasibility of polymeric micro-emulsion particles as a directing template for monolith fabrication with structured pores

Enhancing enzyme stability and metabolic functional ability of β-galactosidase through functionalized polymer nanofiber immobilization

A functionalized polystyrene nanofiber (PSNF) immobilized β-galactosidase assembly (PSNF-Gal) was synthesized as a nanobiocatalyst aiming to enhance the biocatalyst stability and functional ability. The PSNF fabricated by electrospinning was functionalized through a chemical oxidation method for enzyme binding. The bioengineering performance of the enzyme carriers was further evaluated for bioconversion of lactose to galacto-oligosaccharides (GOS). The modified PSNF-Gal demonstrated distinguished performances to preserve the same activity as the free β-galactosidase at the optimum pH of 7.0, and to enhance the enzyme stability of PSNF-Gal in an alkaline condition up to pH 10. The PSNF assembly demonstrated improved thermal stability from 37 to 60 °C. The nanobiocatalyst was able to retain 30 % of its initial activity after ninth operation cycles comparing to four cycles with the unmodified counterpart. In contrast with free β-galactosidase, the modified PSNF-Gal enhanced the GOS yield from 14 to 28 %. These findings show the chemically modified PSNF-based nanobiocatalyst may be pertinent for various enzyme-catalysed bioprocessing applications

Effect of Crosslinkers on Immobilization of ß-Galactosidase on Polymethacrylate Monolith.

Advances in biotechnology unfold a new frontier for the development of enzyme-catalysed bioprocess which is green and sustainable in contrast with chemical processes. Immobilization technology appears as a beneficial solution to the uneconomical cost of enzyme operation. Immobilization of enzyme via crosslinking approach has become a technology interest due to the more concentrate enzyme activity in the catalyst compared to other techniques. In this study, two types of crosslinker, glutaraldehyde and hexamethylene diisocyanate at different concentration was investigated in immobilizing β-galactosidase on polymethacrylate monolith. The enzyme activity upon immobilization was measured spectrophotometrically at 405 nm. The immobilized enzyme was further characterized using Fourier Transform Infrared Spesctroscopy (FTIR) and Zeiss Axio Fluorescence Microscope. The findings showed that the optimum enzyme activity was achieved when using 0.05% and 0.01% glutaraldehyde hexamethylene diisocyanate respectively. Beyond that concentration, a significant reduction of enzyme activity was observed. It was found that glutaraldehyde was preferable as crosslinking agent as hexamethylene diisocyanate exhibited stronger effect in reducing enzyme activity. A successful binding of β-galactosidase on polymethacrylate monolith was observed using Fourier-transform infrared spectroscopy (FTIR) and Zeiss Axio Fluorescence microscope. The outcomes of this study indicate the potential of enzyme immobilization on monolith via crosslinking method

Operational stability, regenerability, and thermodynamics studies on biogenic silica/magnetite/graphene oxide nanocomposite-activated candida rugosa lipase

Inorganic biopolymer-based nanocomposites are useful for stabilizing lipases for enhanced catalytic performance and easy separation. Herein, we report the operational stability, regenerability, and thermodynamics studies of the ternary biogenic silica/magnetite/graphene oxide nanocomposite (SiO2 /Fe3 O4 /GO) as a support for Candida rugosa lipase (CRL). The X-ray photo-electron spectroscopy (XPS), X-ray diffraction (XRD), field-electron scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), and nitrogen adsorption/desorption data on the support and biocatalyst corroborated their successful fabrication. XPS revealed the Fe3 O4 adopted Fe2+ and Fe3+ oxidation states, while XRD data of GO yielded a peak at 2θ = 11.67◦, with the SiO2 /Fe3 O4 /GO revealing a high surface area (≈261 m2 /g). The fourier transform infrared (FTIR) spectra affirmed the successful fabricated supports and catalyst. The half-life and thermodynamic parameters of the superparamagnetic immobilized CRL (CRL/SiO2 /Fe3 O4 /GO) improved over the free CRL. The microwave-regenerated CRL/SiO2 /Fe3 O4 /GO (≈82%) exhibited higher catalytic activity than ultrasonic-regenerated (≈71%) ones. Lower activation (Ea) and higher deactivation en-ergies (Ed) were also noted for the CRL/SiO2 /Fe3 O4 /GO (13.87 kJ/mol, 32.32 kJ/mol) than free CRL (15.26 kJ/mol, 27.60 kJ/mol). A peak at 4.28 min in the gas chromatograph-flame ionization detection (GC-FID) chromatogram of the purified ethyl valerate supported the unique six types of 14 hydrogen atoms of the ester (CAS: 539-82-2) in the proton nuclear magnetic resonance (1 H-NMR) data. The results collectively demonstrated the suitability of SiO2 /Fe3 O4 /GO in stabilizing CRL for improved operational stability and thermodynamics and permitted biocatalyst regenerability

Preparation of Polystyrene Microsphere-Templated Porous Monolith for Wastewater Filtration

Porous monoliths prepared using templates are highly sought after for filtration applications due to their good mass transport properties and high permeability. Current templates, however, often lead to the formation of dead-end pores and irregular pore distributions, which reduce the efficiency of the substrate flow across the monolith column. This study focused on the preparation of a microsphere-templated porous monolith for wastewater filtration. The optimal template/monomer ratio (50:50, 60:40, 70:30) was determined, and appropriate template removal techniques were assessed for the formation of homogenous pores. The physicochemical characteristics and pore homogeneity of the monoliths were examined. The 60:40 ratio was determined to result in monoliths with homogeneous pore distributions ranging from 1.9 µm to 2.3 µm. SEM and FTIR investigations revealed that solvent treatment was effective for removing templates from the resulting solid monolith. The water quality assessments revealed reductions in the turbidity and the total number of suspended particles in the tested wastewater of up to 96–99%. The findings of this study provide insightful knowledge regarding the fabrication of monoliths with homogenous pores that are beneficial for wastewater treatment