Evaluation of optimal conditions for cultivation of marine Chlorella sp. as potential sources of lipids, exopolymeric substances and pigments

Marine microalgae are used in aquaculture as a suspension to feed young fishes and shrimps. Marine Chlorella sp. is one of the most attractive marine microalgae because in addition to pigments it can accumulate lipids at a high content (>30 %) and release exopolymeric substances (EPSs) into the culture medium. This study aimed to evaluate the optimal cultivation of marine Chlorella sp. as potential sources of lipids, EPSs and pigments. Among the culturing regimes tested, mixotrophic cultivation mode produced the highest yields of biomass, lipids and EPSs. Several factors affecting mixotrophic cultivation were optimized. An increase in light intensity up to 65 μmol m−2 s−1 and carbon dioxide up to 10 % v/v in air enhanced both biomass and product formation. An increase in glucose concentration up to 1 % w/v enhanced biomass and EPS yields but decreased lipid and chlorophyll contents. A semi-continuous cultivation under optimal conditions produced microalgal biomass of 2.76 g L−1 with a high lipid content of 44.9 % and EPS of 1.46 g L−1. This study has also shown that the microalgal lipid and EPS have potential to be used as biodiesel feedstocks and bioflocculants, respectively. The concomitant production of these valuable products together with the microalgal biomass would be a potential way to offset the production cost and contribute greatly to developing industrialized microalgae cultivation.