Growth and lipid accumulation of indigenous algal strains under photoautotrophic and mixotrophic modes at low temperature

In the present work, 10 strains of algae indigenous to Quebec Province of Canada were used to investigate the performances of lipid accumulation and biomass growth of algae cells in autotrophic and mixotrophic modes at a low cultivation temperature of 10 °C. It is found that mixotrophic cultivation of algae cells brought more steady growth than photoautotrophic growth at low temperature, but had only a weak influence on growth phases, and that the high C/N ratio of the mixtotrophic culture medium played a positive role in algal lipid accumulation. Furthermore, compared with photoautotrophic cultivation, mixotrophic cultivation enhanced lipid accumulation at a cultivation temperature of 10 °C. Most of the experimented algal strains consumed little phosphate in the Bold's Basal Medium used under two trophic modes. The results indicate that it is necessary to further optimize the culture medium used in order to enhance algal growth during mixotrophic cultivation, and that the metabolic mechanisms of these algae in the mixotrophic mode need to be further investigated.