Original Article Effect of nitrogen concentration on growth, lipid production and fatty acid profiles of the marine diatom Phaeodactylum tricornutum

摘要

The marine diatom, Phaeodactylum tricornutum had a high lipid content accumulation under photoautotrophically nitrogen-deficient cultivation. The lipid content ( Y _P/X; 53.04?±?3.26%) was highest with a specific rate of lipid production ( q _P; 1.50?±?0.12?×?10?3?mg/mg?h), attained at the minimized specific growth rate ( μ ; 0.87?±?0.13?×?10?2/h) after 504?h of cultivation. When the specific growth rate ( μ ; 2.47?±?0.02?×?10?2/h) was maximized in nitrogen-sufficient culture (32.09?mg/L NaNO₃), the specific rate of lipid production ( q _P; 0.42?±?0.19?×?10?3?mg/mg?h) was lowered. In this work, the nitrogen concentration with fixed phosphorus concentration was used to monitor the lipid accumulation, as the lower nitrogen concentration favored a higher lipid content percentage, compared with a higher nitrogen concentration. Under nitrogen-deficient conditions, P.?tricornutum produced a large amount of saturated fatty acids, mainly as palmitic acid (C16:0), while palmitoleic acid (C16:1c) was found to be the sole unsaturated fatty acid. On the other hand, eicosapentaenoic acid (C20:5ω3c) was produced in large amounts when there was sufficient nitrogen. Since the biodiesel was qualified based on the fatty acid methyl ester composition, the oil from algae cultured under nitrogen-deficient conditions were considered to meet the biodiesel standard. Thus, P.?tricornutum optimally cultivated under nitrogen-deficient conditions can accumulate a high oil content, which demonstrates its potential as a biodiesel feedstock.