Cooptimization of growth parameters in glycerol mediated mixotrophic cultivation of microalgae in a bubble column photobioreactor

Abstract

Microalga is a primary source for third generation biofuels due to its high photosynthetic ability, which can be exploited to produce bioethanol, biodiesel, biohydrogen, as well as value-added coproducts such as proteins, carbohydrate, vitamin, omega fats, carotenoids etc. Using glycerol (a primary by-product of biodiesel industry) for mixotrophic algal cultivation can improve the economic and environmental sustainability of the biodiesel industry.Chlorella sorokiniana is cultured mixotrophically in modified TAP media using glycerol as the sole organic carbon source and atmospheric CO2 as the inorganic carbon source in a 1 L bubble column PBR with photoperiod of 18h :6h (Light:Dark). This study shows how theco-optimization of reactor scale parameters augments biomass yield at the cellular level by enhancing the synergy between autotrophic and heterotrophic pathways in the molecular level. A heterotrophic parameter (initial glycerol loading) and an autotrophic parameter (reactor illumination) are employed to engineer the mixotrophic algal cultivation process. The operating range of reactor illumination and initial glycerol loading are 3500-14000 Lux and 0.6-2.2 mL/L, respectively.