Heterotrophic culture of Chlorella pyrenoidosa using sucrose as the sole carbon source by co-culture with immobilized yeast

Glucose is normally used as the carbon source for heterotrophic cultivation of algal cells, whereas sucrose is difficult to be heterotrophicly utilized by them. In this study, a new co-culture system was developed through mixed culture of Chlorella pyrenoidosa with immobilized Saccharomyces cerevisiae in the dark to effectively obtain pure algal suspension using sucrose as only carbon source. In this system, a pure algal suspension with a concentration of 2.08 g/L was obtained. The lipid content reached 29%, which was higher than that obtained in glucose contained system. In addition, the immobilized yeast beads were repeatedly used for at least three times. Through immobilization, the choice for the yeast strains that are able to hydrolyze sucrose was not limited by its product and pure algal suspension was efficiently obtained. This strategy may effectively decrease the cost of carbon source in the heterotrophic cultivation of microalgae.