Fluid mixing and oxygen transfer in cell suspensions ofTaxus chinensis in a novel stirred bioreactor (original) (raw)
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Cultivation of plant cells in a stirred vessel: Effect of impeller design
Biotechnology and Bioengineering, 1990
Suspension cultures of Nicotiana tabacum were grown in a batch fermentor using different agitation systems. The effects of the impeller type, size, and agitation speed on the productivity of cell mass and secondary metabolites (phenolics) have been investigated. The use of a large, flat-bladed impeller (diameter 7.6 cm; width 14.0 cm) improved culture growth significantly over systems using a regular, flat-bladed impeller (diameter 5.6 cm; width 1.5 cm). An impeller of the same dimensions as the 14.O-cm-wide, large, flat-bladed impeller with sail cloth blades yielded a higher maximum growth rate in the exponential phase but resulted in a longer lag phase. Overall (intracellular and extracellular) phenolics concentration showed a direct relationship to culture growth rate whereas extracellular concentrations were a function of agitation conditions. Power consumption and flow pattern studies were also completed to further characterize the different impellers tested.
Plant cell, tissue and …, 2000
Strategies to overcome foaming and wall-growth during the cultivation of Morinda elliptica (Rubiaceae) cell suspension cultures in a stirred-tank bioreactor are described. Of all the strategies applied, only bubble-free aeration was successful in eliminating foaming by 100%. Despite the foaming effect of around 40% in G medium strategy with 0.012% (v/v) antifoam, the maximum dry cell weight attained (19.2 g l −1 ) and anthraquinone (AQ) content (4.0 mg g −1 DW) was nearly three times higher than that achieved in cultivation using 0.025% (v/v) antifoam. For continuous cell growth, the effect of inoculum age should also be considered when anti-foam is to be added. P medium strategy, without antifoam addition, not only promoted both growth (18 g l −1 ) and AQ production (9.8 mg g −1 DW), but also resulted in lower foaming and wall-growth (below 30% level), and higher foaming reduction (30-40%).
Biotechnology and Bioengineering, 1995
The kinetics of biomass accumulation, nutrient uptake, and taxol production of Taxus baccata cell suspensions were examined in three bioreactor configurations, viz. 250-mL Erlenmeyer flasks, 1-L working volume pneumatically mixed (PMB), and stirred tank (STB) bioreactors. Qualitatively similar kinetics were observed in all three bioreactor types. Biomass accumulation and specific nutrient uptake rates exhibited biphasic characteristics. Carbohydrate uptake and biomass accumulation substantially ceased when phosphate was depleted from the medium. Phosphate was identified as a possible growthlimiting nutrient. Taxol accumulated exclusively in the second phase of growth. A maximum taxol concentration of 1.5 mg/L was obtained in the PMB which was fivefold greater than that obtained in the Erlenmeyer flasks and the STB, but the relative kinetics of taxol production was the same in all three reactor types. Biomass yields were calculated from the kinetic data and a stoichiometry for biomass formation was evaluated. The similarity of kinetics in the three bioreactor configurations suggests that taxol production by T. baccata cell suspensions is amenable t o scaleup.
Enzyme and Microbial Technology, 1991
The effect of long-term high shear and impeller design on the growth and alkaloid accumulation by Catharanthus roseus cultures grown in stirred-tank bioreactors has been studied. As the impeller speed was increased from 100 to 300 rev min-l, the growth rate increased and the maximum biomass and alkaloid accumulation decreased. An inclined impeller reduced the decrease in aggregate size as the impeller speed was increased to 300 rev min-l, but the expansion index was not affected. The C. roseus also proved capable of growth at an impeller speed of l,O00 rev min-J, and inclined impellers increased the growth rate, alkaloid accumulation, and expansion index.
Biochemical Engineering Journal, 2016
Plant cell culture is a useful technology for the production of secondary metabolites with commercial and pharmaceutical value. The rheology, morphology or aggregation of cell suspension have different applications in flow systems, bioreactor design and unit operations. This suggests solutions to mixing, mass transfer, hydrodynamic stress and cell growth problems. In this study, some morphological aspects associated with elliptical form factor and the tendency to form cell aggregates of Azadirachta indica, Borojoa patinoi and Thevetia peruviana cell cultures were evaluated in shake flasks. The rheological behavior through rheograms for cell concentrations of 0, 4, 8 and 12 gDW L-1 was also evaluated. From this data, properties and parameters like apparent viscosity, Reynolds number, phase state and volumetric power were calculated for shake flasks of 250 and 500 ml. The results showed a dilatant behavior of the culture medium and pseudo-plastic behavior of cell cultures. This last behavior increases with cell concentration and size of the cell aggregates. Rheograms for all cell concentrations of A. indica, were significantly different from the other two species. Culture conditions like shaker orbit diameters and flask volumes were recommended in order to favor an adequate cell growth and mass transfer in plant cell cultures.
Characterization of aggregate size in Taxus suspension cell culture
Plant Cell Reports, 2010
Plant cells grow as aggregates in suspension culture, but little is known about the dynamics of aggregation, and no routine methodology exists to measure aggregate size. In this study, we evaluate several different methods to characterize aggregate size in Taxus suspension cultures, in which aggregate diameters range from 50 to 2,000 μm, including filtration and image analysis, and develop a novel method using a specially equipped Coulter counter system. We demonstrate the suitability of this technology to measure plant cell culture aggregates, and show that it can be reliably used to measure total biomass accumulation compared to standard methods such as dry weight. Furthermore, we demonstrate that all three methods can be used to measure an aggregate size distribution, but that the Coulter counter is more reliable and much faster, and also provides far better resolution. While absolute measurements of aggregate size differ based on the three evaluation techniques, we show that linear correlations are sufficient to account for these differences (R 2 > 0.99). We then demonstrate the utility of the novel Coulter counter methodology by monitoring the dynamics of a batch process and find that the mean aggregate size increases by 55% during the exponential growth phase, but decreases during stationary phase. The results indicate that the Coulter counter method can be routinely used for advanced process characterization, particularly to study the relationship between aggregate size and secondary metabolite production, as well as a source of reliable experimental data for modeling aggregation dynamics in plant cell culture.
Growth kinetics ofvitis vinifera cell suspension cultures: I. Shake flask cultures
Biotechnology and Bioengineering, 1995
Vitis vinifera cell suspension cultures carried out in shake flasks were closely examined for biomass growth and cell division in relation to carbohydrate, NH, , NO3, PO, , and dissolved oxygen (DO) consumption. After inoculation, the oxygen uptake rate of the cultures measured on-line was observed t o increase continuously to a maximum value of 3.8 mmol 0, L-' h -' at day 7 when cell division ceased and dissolved oxygen reached its lowest level of 17% air saturation. During this first phase of growth, the specific oxygen uptake rate remained constant at -0.6 mmol 0, g-' dw h-' or -2.2 pmol 0, (lo6 cells)-' h-', whereas dry biomass concentration increased exponentially from 1.5 to 6.0 g dw L-'. Thereafter, dry biomass concentration increased linearly to -14 g dw L-' at day 14 following nitrate and carbohydrate uptake. During this second phase of growth, the biomass wet-to-dry weight ratio was found to increase in an inverse relationship with the estimated osmotic pressure of the culture medium. This corresponded to inflection points in the dry and wet biomass concentration and packed cell volume curves. Furthermore, growth and nutrient uptake results suggest that extracellular ammonium or phosphate ion availability may limit cell division. These findings indicate that cell division and biomass production of plant cell cultures may not always be completely associated, which suggests important new avenues to improve their productivity. 0 1995 John Witey & Sons, Inc.