Effects of organic carbon source on growth, biochemical components and fatty acid composition of Phaeodactylum tricornutum

Abstract:

We examined the effects of three organic carbon sources on mixotrophic growth, biochemical components and fatty acid composition of Phaeodactylum tricornutum. Mixotrophically, P. tricornutum grew faster and had shorter doubling time. The biomass of P. tricornutum was greatly enhanced under mixotrophic condition with its highest biomass of 713 mg/L after 16 days, in medium containing 100 mmol/L glycerol. This was 1.60-fold of that obtained under autotrophic condition. The biomass during mixotrophic culture with 100 mmol/L glucose and 100 mmol/L acetate was 1.28-fold and 1.21-fold of that obtained under autotrophic condition, respectively. Compared with autotrophic condition, the content of soluble protein decreased obviously, whereas the content of soluble carbohydrate and total lipid increased. The content of lipid during mixotrophic culture with 100 mmol/L acetate and 100 mmol/L glycerol was 1.43-fold and 1.20-fold of that obtained under autotrophic condition, respectively. There was no difference between lipid content of mixotrophic growth with 100 mmol/L glucose and that of autotrophic condition. The eicosapentaenoic acid (EPA) content and yield was 6.23% and 36.59 mg/L during mixotrophic culture with 100 mmol/L acetate. These were 1.10-fold and 1.40-fold of that obtained under autotrophic condition, respectively. The EPA content and yield with glycerol and glucose were lower than that obtained under autotrophic condition. These results indicated that mixotrophic cultivation with acetate was beneficial to produce EPA.

Key words:organic carbon source, Phaeodactylum tricornutum, mixotrophic, growth, lipid, fatty acid, EPA