Optimizing physicochemical factors for two-stage cultivation of newly isolated oleaginous microalgae from local lake as promising sources of pigments, PUFAs and biodiesel feedstocks

Abstract

Oleaginous microalgae were newly isolated from local lake and screened for their high lipid content and suitable composition under two-stage cultivation, in which nitrogen-rich was used for promoting cell growth and nitrogen-starvation was used for stimulating lipid accumulation. Effects of key physicochemical factors on cell growth, pigment and lipid contents of selected strains were intensively investigated. Optimal conditions for attaining high biomass and lipids were: addition of 0.5% salt, slightly high light intensity of 55 μmol·photon·m−2 s−1 and temperature of 30 °C. Under nitrogen-starvation, the selected strains showed 1.3–1.6 folds increase in lipid content but with decreased pigment contents. Among the strains screened, Scenedesmus sp. SPP and Chlorella sp. PPS showed high potential as PUFAs/pigments sources while marine Chlorella sp. lipids showed excellent biodiesel properties, especially under nitrogen-starvation. This study has shown the optimal physicochemical factors for two-stage cultivation of microalgae which may greatly contribute to industrialization of microalgae-based biofuels and bioproducts.