Cultivation of plant cells in a stirred vessel: effect of impeller design

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 14.0-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.