Down-scale of hydrodynamic shear effects on suspended cells

VÍCTOR D. BUSTO; ARIEL CALABRÓ-LÓPEZ; JULIÁN RODRÍGUEZ-TALOU; ANA M. GIULIETTI; JOSÉ C. MERCHUK

Malta

Congreso; 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT 2012); 2012

University of Pretoria - South Africa

Suspension cultures of Rubia tinctorum, an anthraquinones (AQs) producer, were grown in four-baffled shake flasks agitated at 100 rpm and at 360 rpm. The effect of shear stress and light irradiation on cell viability, biomass, and AQs production was evaluated. When cells were cultured at 360 rpm, a decrease in biomass concentration (28%) was observed compared with control cultures. Loss of cell viability measured as Evans Blue uptake increased 60% and 40% after 7 days of shear stress in presence and in absence of light, respectively. The negative effects of shear stress on viability and biomass concentration were reverted after 14 days of culture. AQs accumulation increased up to 155% and 216% compared with control after 14 days of shear stress in presence and absence of light, respectively. The maximum AQs productivity was 51.3 μmol/L.d, which was attained without light. This productivity corresponds to a AQs increase of 129% comparing to control conditions. Absence of light irradiation played an important role on AQs production, making a difference of approximately 40% between stressed cells with or without light irradiation at 14 days of culture. The biomass concentration and AQs production obtained using baffled shake flasks agitated at 360 rpm were similar to that achieved previously in R. tinctorum suspension cultures growing in a stirred tank bioreactor operating at 450 rpm. It can be concluded that this down-scaled and simple culture system is a suitable and valid alternative to study intracellular mechanisms of shear stress-induced AQs production in R. tinctorum cell suspension cultures.