High productivity cultivation of a heat-resistant microalga Chlorella sorokiniana for biofuel production

To augment biomass and lipid productivities of heterotrophic cultured microalgae Chlorella sorokiniana, the influence of environmental temperature and medium factors, such as carbon source, nitrogen source, and their initial concentrations was investigated in this study. The microalga C. sorokiniana could tolerate up to 42 °C and showed the highest growth rate of 1.60 d−1 at 37 °C. The maximum dry cell weight (DCW) and corresponding lipid concentration was obtained with 80 g L−1 of initial glucose and 4 g L−1 of initial KNO3 at 37 °C. In 5-L batch fermentation, the DCW increased dramatically from 0.9 g L−1 to 37.6 g L−1 in the first 72 h cultivation, with the DCW productivity of 12.2 g L−1 d−1. The maximum lipid content of 31.5% was achieved in 96 h and the lipid productivity was 2.9 g L−1 d−1. The results showed C. sorokiniana could be a promising strain for biofuel production.