The effect of glycerol and carbonate on the growth and lipid production of Isochrysis galbana under different cultivation modes

This study aimed to investigate the potential of using glycerol and carbonate as different carbon sources for the production of biomass and the lipid content of Isochrysis galbana under heterotrophic, mixotrophic and phototrophic conditions. Glycerol as the carbon source inhibited the growth of I. galbana in the heterotrophic mode, while growth was enhanced in the mixotrophic conditions as compared to phototrophic conditions. Algal dry weight and lipid content were enhanced as glycerol concentration was increased from 0 to 100 mM; this was such that the highest biomass production and lipid content occurred at 50 mM glycerol under mixotrophic conditions (0.23 g L −1 , 29% of dry weight) and at 25 mM glycerol under heterotrophic conditions (0.25 g L −1 , 19.6% of dry weight). The effect of carbonate as the inorganic carbon source on the growth of I. galbana under mixotrophic conditions was investigated; the highest biomass (0.38 g L −1 ) and lipid content (30.7% of dry weight) were achieved at 1 g L −1 carbonate. It was, therefore, demonstrated that the growth and lipid content of I. galbana could be improved by using the mixotrophic culture at 50 mM glycerol; especially, carbonate as the inorganic carbon could enhance CO 2 biofixation to 1 g L −1 .