Statistical optimization of airlift photobioreactor for high concentration production of torularhodin pigment

The performance of an airlift photobioreactor for carotenoids production by Rhodotorula rubra yeast from glucose as sole carbon source was statistically studied in batch operations. In this study, the effects of aeration rate (Xi), initial pH (X-2), and white-light irradiation intensity (X-3) on biomass formation (Y-1) and the specific carotenoid production rate (Y-2) were studied by face center central composite experimental design (FCCCD). The analysis of variances indicated that the light irradiation intensity and aeration rate were the most influential factors on the specific carotenoid production rate and biomass formation in the bioreactor, respectively. The results of the statistical studies showed that the following combination of the test factors was corresponded to an optimal conditions in the bioreactor for achieving simultaneous highest biomass concentration and specific carotenoid production rate: aeration rate-0.465 wm, initial pH=6.6, and light irradiation intensity-1780 lx. In this optimum conditions, torularhodin as prominent carotenoid pigment (86%) was produced.