Surface Modifications for Controlled and Optimized Cell Immobilization by Adsorption: Applications in Fibrous Bed Bioreactors Containing Recombinant Cells

Abstract

The effects of surface properties of S. cerevisiae strains 468/pGAC9 and 468 on adhesion to polyethylenimine (PEI) and/glutaraldehyde (GA) pretreated cotton (CT), polyester (PE), polyester + cotton (PECT), nylon (NL), polyurethane foam (PUF), and cellulose re-enforced polyurethane (CPU) fibers were investigated. Process parameters (circulation velocity, pH, ionic strength, media composition and surfactants) were also examined. 80, 90, and 35% of the cells were adsorbed onto unmodified CT, PUF and PE, respectively. PEI-GA pre-treated CT and alkali treated PE yielded 25% and 60% cell adhesion, respectively. Adsorption rate (K a ) ranged from 0.06 to 0.17 for CT and 0.06 to 0.16 for PE at varied pH. Adhesion increased by 15% in the presence of ethanol, low pH and ionic strength, and decreased by 23% in the presence of yeast extract and glucose. Shear flow and 1% Triton X-100 detached 62 and 36% nonviable cells from PE and CT, respectively, suggesting that cell immobilization in fibrousbed bioreactors can be controlled to optimize cell density for long-term stability.

Immobilization of microbial cells: A promising tool for treatment of toxic pollutants in industrial wastewater

“…The highest efficiency in the degradation of ophthalate by cells Bacillus-spp. immobilized in polyurethane foam, in relation to alginate was reported by Donlan (2002) and Kilonzo and Bergougnou (2012). Patil et al (2006).…”

“…Different from the inherent problems associated with cell entrapment, cell immobilization through adsorption provides a direct contact between nutrients and the immobilized cells thus, eliminating such concerns (Braschler et al, 2005). This cell immobilization technique involves the transport of the cells from the bulk phase to the surface of support (porous and inert support materials), followed by the adhesion of cells, and subsequent colonization of the support surface (Kilonzo and Bergougnou, 2012).…”

“…The surface structures of bacterial cells (flagella and other appendages), superficial charges and hydrophobicity also play an important part in the cell adherence to solid surfaces (Donlan, 2002;Chae et al, 2006;Oulahal, et al, 2008). The composition of the medium, its pH, and environmental conditions considerably influence the adsorption of cells by changing their electrokinetic potential (Stanley, 1983;Fletcher and Pringle, 1986;Kilonzo and Bergougnou, 2012). The surface properties of adsorbents also affect the process of cell immobilization (Busalmen andSanchez, 2001, Ubbink andSchar-Zammaretti, 2007).…”

Characteristics of a novel low density cell-immobilized magnetic supports in liquid magnetically stabilized beds

“…Other authors [34] reported an increase of cell loading with increasing ionic strength and others [35] reported no net apparent effect of ionic strength on the cell adsorption. However, in viable cell immobilization, it is expected that under the experimental conditions, a high ionic strength might destabilize immobilized cells and prevents the interaction between cells and supports surfaces, and thereby reduces the cell adhesion [36].…”

“…Phase diagrams are usually constructed based on the experimental results in order to understand the performance of the magnetic particles under the mutual effect of the magnetic field used for stabilization or separation purposes and the liquid flow in the bed [36]. These experiments were conducted in "magnetizing first" mode in which the magnetic particles were poured in the water filled column to form a packed bed of certain height.…”