5-20: High cell density culture of microalgae sensitive to substrate inhibition

Monday, April 29, 2013
Exhibit Hall
R. S. Coelho, A. D. S. Vidotti, M. R. Piovani and T. T. Franco, School of Chemical Engineering, State University of Campinas, Campinas, Brazil
Heterotrophic growth of microalgae supported by a carbon source can overcome the major limitations found in photosynthetic process such as dependence on light and weather conditions and achieve higher biomass concentrations and productivities. However, most species of microalgae are readily inhibited at low concentrations of organic substrates. This study focused on the biomass growth and lipid accumulation of Chlorella vulgaris grown in the dark with glucose as carbon source. Different glucose concentrations were tested in shake flasks in order to determine the optimum carbon source concentration and the inhibitory effect on biomass growth. In shake flasks optimal biomass growth and productivity (0.66 g·L-1·d-1) were reached using glucose at 1.0 %, whereas higher concentrations were highly growth inhibitory. The optimized conditions were used to design a fed-batch strategy in a 2 L bioreactor. The culture was fed eleven times with a nutrient solution and attained the final biomass concentration and productivity of 41 ± 1 g·L-1 and 6.6 g·L-1·d-1, respectively. The final lipid content attained 23 ± 1 % with an overall lipid productivity of 1.5 g·L-1·d-1. Fatty acid analysis showed that up to 24 % of lipid content was composed by oleic acid, followed by linoleic acid (22 %) and palmitic acids (20 %). The results showed that microalgae highly sensitive to substrate inhibition can be grown up to high biomass concentrations and productivities. Acknowledgements: FAPESP, CAPES and CNPQ.