Oxygen diffusivity in gel beads containing viable cells

Abstract

This article proposes a simple steady-state method for measuring the effective diffusion coefficient of oxygen (D(e)) in gel beads entrapping viable cells. We applied this method to the measurement of D(e) in Ca- and Ba-alginate gel beads entrapping Saccharomyces cerevisiae and Pseudomonas ovalis. The diffusivity of oxygen through gel beads containing viable cells was measured within an accuracy of +/-7% and found not to be influenced by cell density (0-30 g/L gel), cell type, and cell viability in gel beads. The oxygen diffusivity in the Ca-alginate gel beads was superior to that of the Ba-alginate gel beads, and the D(e) in the Ca-alginate gel beads nearly equalled the molecular diffusion coefficient in the liquid containing the gel beads. The oxygen concentration profile in a single Ca-alginate gel bead was calculated and compared to the distribution of mycelia of Aspergillus awamori grown in that gel bead. This procedure indicated that the oxygen concentration profile is useful for the estimation of the thickness of the cell layer in a gel bead. Numerical investigation revealed that high effectiveness factors, greater than 0.8, could be obtained using microgel beads with a radius of 0.25 mm.

Specific ATP and specific oxygen uptake rate in immobilized cell aggregates: Experimental results and theoretical analysis using a structured model of immobilized cell growth

“…In contrast to our investigation, as noted previously, research performed on microbial cells entrapped in gel beads indicated that the cells maintained 90-95% of their activity after immobilization compared with suspended cells (Kurosawa et al, 1989;van Ginkel et al, 1983). This might be explained by the fact that 90% of the cells entrapped in gel beads are growing close to the biocatalyst/bulk liquid interface, while the rest of the bead volume is almost cell free (Kurosawa et al, 1989;Monbouquette et al, 1990;Wijffels, 1991), and additional cell growth results in cell leakage from the gel (Robinson et al, 1985) rather than in cell migration inwards.…”

“…This might be explained by the fact that 90% of the cells entrapped in gel beads are growing close to the biocatalyst/bulk liquid interface, while the rest of the bead volume is almost cell free (Kurosawa et al, 1989;Monbouquette et al, 1990;Wijffels, 1991), and additional cell growth results in cell leakage from the gel (Robinson et al, 1985) rather than in cell migration inwards. The model used here supports this explanation since these gel entrapped cells are effectively acting as cells at the interface in Figure 11.…”

“…On the other hand, Wijffels et al (1991) and Kurosawa et al (1989) who worked with immobilized Nitrobacter agilis, and Saccharomyces cerevisiae and Pseudomonas ovalis in gel beads, respectively, found separately that the cells retained more than 90% of their activity after immobilization using Specific Oxygen Uptake Rate (SOUR) [mg O 2 g −1 (dry biomass) h −1 ] as the biomass activity indicator. Such differences in immobilized biomass activity between selfattached and entrapped cell systems indicate that immobilized biomass activity depends strongly on the particular characteristics of the microbial system and its interaction with the support matrix.…”

Hepatocytes Entrapped in Alginate Gel Beads and Cultured in Bioreactor: Rapid Repolarization and Reconstitution of Adhesion Areas

“…An important feature of our system is the good permeability of alginate matrix to oxygen and nutrients [Miura et al, 1987;Kurosawa et al, 1989]. Since oxygen supply within gel beads decreases, depending on bead size and entrapped cell density [Tziampazis and Sambanis, 1995], the condition under continuous flow is revealed as a decisive factor in the maintenance of cell viability, as demonstrated by 31 P NMR in vivo spectroscopy [Miccheli et al, 2000].…”

Production of bioethanol as a alternative fuel from corn by free and immobilized yeast Saccharomyces cerevisiae var. ellipsoideus

“…Smatra se da su ĉestice malog preĉnika pogodnije za izvoĊenje fermentacije s obzirom da obezbeĊuju bolji prenos mase. Kurosawa i saradnici [215] su u svom radu pokazali da je optimalan preĉnik alginatnih ĉestica sa ćelijama kvasca S. cerevisiae 0,5 mm.…”