EFFECTS OF LIGHT-PATHs AND NITROGEN CONCENTRATION ON THE GROWTH, TOTAL LIPIDS AND ARACHIDONIC ACID ACCUMULATION OF PARIETOCHLORIS INCISA

This study explored effects of 3 light-paths (LP) of column and flat plat photobioreactors under two kinds of nitrogen concentrations on the growth, total lipid and AA content of Parietochloris incisa using BG-11 medium. The results showed that cell growth rate increased by the smaller light-path of two kinds of photobioreactors. The maximal biomass were 5.09 g/L in column photobioreactor (2.5 cm LP) and 2.98 g/L (3.0 cm LP) in flat plate photobioreactor with nitrogen concentration at 17.6 mmol/L. The highest total lipid and AA content at the biggest length of light-path under 1.0 mmol/L nitrogen concentration were 39.23% and 13.21% in column photobioreactor (6.0 cm LP) and there were 40.74% and 11.33% in flat plate photobioreactor (5.0 cm LP). In addition, the maximal volumetric productivity of total lipid was 216.39 mg/(L·d) in column photobioreactor (2.5 cm LP) under 17.6 mmol/L nitrogen concentration and it was 135.93 mg/(L·d) in flat plate photobioreactor (1.5 cm LP) under 1.0 mmol/L nitrogen concentration. The AA volumetric productivity reached the maximum level in the biggest light-path of column 21.65 mg/(L·d) and flat plate photobiorector 19.42 mg/(L·d) under 1.0 mmol/L nitrogen concentration. These results indicate that the 6.0 cm light-path column photobioreactor or 5.0 cm light-path of flat plate photobioreactor under 1.0 mmol/L nitrogen concentration are the best condition to culture Parietochloris incisa for AA production.