Effects of inorganic carbon concentration on carbon formation, nitrate utilization, biomass and oil accumulation of Nannochloropsis oculata CS 179.

This investigation examined the effects of the inorganic carbon concentration (4, 0.8 and 0 g/L NaHCO(3)) on the carbon formation, nitrate utilization, growth and fatty acids compositions of Nannochloropsis oculata. The dissolved inorganic carbon (DIC) concentration in the three treatments decreased sharply during the first 6 days, and the percentage of dissolved organic carbon (DOC) (% of total organic carbon (TOC)) decreased with the depletion of the DIC. The NO(3)(-) assimilation of the algae was correlated with the DIC concentration. The algae in the highest DIC treatment had the highest specific grow rate (0.0843 d(-1)) (P<0.0001), and their biomass and fatty acid methyl esters (FAME) productivity were 84.00 and 9.69 mg/L/d, respectively (P<0.0001). Contents of C16 and C18 series (% of FAME) were high and the C16:0 increased with the decrease of C18:1 during the cultivation. The iodine value (IV) of the algae was low at the low DIC media.