Animal cells are sensitive to direct bubble aeration, as several author have
observed (e.g. [55, 56]). Pluronic F-68 (BASF, Ludwigshafen) is a copolymer
of poly(oxyethylene) (POE) and poly(oxypropylene) (POP) with a relative
molecular weight of about 8400, of which 80% is POE. In the molecule the
hydrophobic POP moiety is flanked by two hydrophilic POE moieties. This
surfactant have been widely used as a protective agent against hydrodynamic
cell damage, because the direct cell–bubble interaction is eliminated. However,
in medium supplemented with Pluronic F-68, the foaminess considerably
increased. The highest foaming was observed in the middle of the exponential
growth rate, with less foam being produced in the stationary and dying phases.
To suppress the foam formation a silicone AFA (30% antifoam C emulsion;
Sigma, USA) was used. Foam was completely eliminated in a medium supplemented with greater than 50 ppm AFA and 0.2% (w/v) Pluronic F-68. Relatively
constant cell growth was found both in the bioreactor until 200 ppm AFA concentration; a marked reduction in cell growth was observed above that.
Contrary to cell growth, relatively high monoclonal antibody (MAB) concentration was found in medium containing 200 ppm AFA. This enhancement
effect on MAB concentration is attributed to the increased specific antibody
production rate observed in the presence of Pluronic F-68 under lower cell
growth. However, the cell damage by bubbles increased, probably because the
AFA reduces the protective effect of Pluronic F68.
Van der Pol et al. [54] investigated the influence of a silicone AFA on the
shear sensitivity of hybridoma cells in sparged cultures. They supplemented the
medium with 1 g l
–1 poly(ethylene glycol) PEG 6000 and PEG 20,000 to protect
the cells from hydrodynamic damage. To suppress the foaming caused by the
Recovery of Proteins and Microorganisms from Cultivation Media by Foam Flotation
211
Fig. 4. Variations in the bubble velocity in recombinant E. coli culture at 13 and 16 h as a function of the time after the maximum velocity had been attained with SE9 AFA addition [51]
observed (e.g. [55, 56]). Pluronic F-68 (BASF, Ludwigshafen) is a copolymer
of poly(oxyethylene) (POE) and poly(oxypropylene) (POP) with a relative
molecular weight of about 8400, of which 80% is POE. In the molecule the
hydrophobic POP moiety is flanked by two hydrophilic POE moieties. This
surfactant have been widely used as a protective agent against hydrodynamic
cell damage, because the direct cell–bubble interaction is eliminated. However,
in medium supplemented with Pluronic F-68, the foaminess considerably
increased. The highest foaming was observed in the middle of the exponential
growth rate, with less foam being produced in the stationary and dying phases.
To suppress the foam formation a silicone AFA (30% antifoam C emulsion;
Sigma, USA) was used. Foam was completely eliminated in a medium supplemented with greater than 50 ppm AFA and 0.2% (w/v) Pluronic F-68. Relatively
constant cell growth was found both in the bioreactor until 200 ppm AFA concentration; a marked reduction in cell growth was observed above that.
Contrary to cell growth, relatively high monoclonal antibody (MAB) concentration was found in medium containing 200 ppm AFA. This enhancement
effect on MAB concentration is attributed to the increased specific antibody
production rate observed in the presence of Pluronic F-68 under lower cell
growth. However, the cell damage by bubbles increased, probably because the
AFA reduces the protective effect of Pluronic F68.
Van der Pol et al. [54] investigated the influence of a silicone AFA on the
shear sensitivity of hybridoma cells in sparged cultures. They supplemented the
medium with 1 g l
–1 poly(ethylene glycol) PEG 6000 and PEG 20,000 to protect
the cells from hydrodynamic damage. To suppress the foaming caused by the
Recovery of Proteins and Microorganisms from Cultivation Media by Foam Flotation
211
Fig. 4. Variations in the bubble velocity in recombinant E. coli culture at 13 and 16 h as a function of the time after the maximum velocity had been attained with SE9 AFA addition [51]