Switching cultivation for enhancing biomass and lipid production with extracellular polymeric substance as co-products in Heynigia riparia SX01

Switching cultivation (mixotrophic-heterotrophic, 12 h:12 h) of Heynigia riparia SX01 was studied, the maximum biomass concentration of 3.55 g L−1 and lipid yield of 1.45 g L−1 were achieved after 8 days cultivation. The extracellular polymeric substance (EPS) was developed as co-product. Addition of MgSO4 could enhance the production of EPS. The highest amount of 0.60 g L−1 EPS was obtained with the addition of 2 g L−1 MgSO4, the self-flocculation efficiency was as high as 83% at this condition. The total lipid and lipid fractions did not show differences with extra MgSO4. Based on the above results, a new biodiesel production model was proposed: culturing Heynigia riparia SX01 with extra 2 g L−1 MgSO4 by switching cultivation and using self flocculation to collect microalgae for biodiesel production, while EPS was collected as valuable co-products.