Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

Abstract

The objective of this work was to develop a hydrogel-coated monolith for the entrapment of penicillin G acylase (E. coli, PGA). After screening of different hydrogels, chitosan was chosen as the carrier material for the preparation of monolithic biocatalysts. This protocol leads to active immobilized biocatalysts for the enzymatic hydrolysis of penicillin G (PenG). The monolithic biocatalyst was tested in a monolith loop reactor (MLR) and compared with conventional reactor systems using free PGA, and a commercially available immobilized PGA. The optimal immobilization protocol was found to be 5 g l−1 PGA, 1% chitosan, 1.1% glutaraldehyde and pH 7. Final PGA loading on glass plates was 29 mg ml−1 gel. For 400 cpsi monoliths, the final PGA loading on functionalized monoliths was 36 mg ml−1 gel. The observed volumetric reaction rate in the MLR was 0.79 mol s−1 m−3monolith. Apart from an initial drop in activity due to wash out of PGA at higher ionic strength, no decrease in activity was observed after five subsequent activity test runs. The storage stability of the biocatalysts is at least a month without loss of activity. Although the monolithic biocatalyst as used in the MLR is still outperformed by the current industrial catalyst (immobilized preparation of PGA, 4.5 mol s−1 m−3catalyst), the rate per gel volume is slightly higher for monolithic catalysts. Good activity and improved mechanical strength make the monolithic bioreactor an interesting alternative that deserves further investigation for this application. Although moderate internal diffusion limitations have been observed inside the gel beads and in the gel layer on the monolith channel, this is not the main reason for the large differences in reactor performance that were observed. The pH drop over the reactor as a result of the chosen method for pH control results in a decreased performance of both the MLR and the packed bed reactor compared to the batch system. A different reactor configuration including an optimal pH profile is required to increase the reactor performance. The monolithic stirrer reactor would be an interesting alternative to improve the performance of the monolith-PGA combination.

Diffusion properties of bacteriophages through agarose gel membrane

“…Our two‐chamber diffusion device also consists of two compartments separated by a porous filter paper or membrane, and it is useful for research on diffusion properties in biofilms using hydrated membranes or biofilms in the block frame. As hydrated polysaccharide gels are similar in structure to biofilm EPS matrix, many researchers have utilized polymer gels like alginate, porcine gastric mucus, or agar to model biofilm state 24, 25. Here, we have used agarose as a representative hydrated gel.…”

Sorption of Cu(II) Ions on Chitosan-Zeolite X Composites: Impact of Gelling and Drying Conditions

“…The gelling properties of chitosan allow it to be shaped in geometries and sizes more adapted to each specific use [30,31,32,33]. Its suitability as a matrix for the formation of zeolite beads has been recognized [34] and the investigation of chitosan-inorganic composites has given rise to a prolific field of research aimed at applications in the fields of medical devices [35], pollution control [36], catalysis [37,38,39], photoluminescence [40,41] and membrane separation [42].…”

Emerging Enzyme-Based Technologies for Wastewater Treatment

“…Immobilization onto nanosupports such as nanotubular aluminosilicate (71), graphene oxide (72), carbon nanotubes (73)(74)(75), graphene oxide sheets (74), nanodiamonds (76), and metal-oxide particles (77), was achieved either through physical or chemical means or through encapsulation into a gel (78) or membrane (79,80). Optimization of the immobilization conditions at any of these nanosupport interfaces involved controlling the enzyme interactions with the nanosupport or encapsulator (with or without a linker) (74) to preserve its functionality and catalytic behavior.…”