Effects of urea concentration on the growth and characteristic of eicosapentenoic acid accumulation of Pinguiococcus pyrenoidosus(Pinguiophyceae)

Objective To investigate the effects of nitrogen concentration on the growth,fatty acid composition and EPA content of P.pyrenoidosus CCMP 2078.Methods Using GC-MS to determine the composition and contents of fatty acids.Results The results showed that the algae hardly grow when the nitrogen concentration was lower than 0.069 mmol·L-1.The maxima specific growth rate(μ) of 0.212 d-1,the highest biomass and cell density(7.7×106 cells· mL-1 and 0.14 g· L-1 respectively) were reached when the nitrogen concentration was 1.38 mmol·L-1.However,the growth was significantly suppressed when the nitrogen concentration was increased from 1.38 nmol·L-1 to 5.52 mmol·L-1.The fatty acid composition was different under various nitrogen concentrations.The highest EPA and PUFAs content(15.66% and 28.65% respectively) were reached at the nitrogen concentration of 1.38 mmol·L-1.In the range of nitrogen concentration from 0.0069 mmol·L-1 to 1.38 mmol·L-1,the EPA and PUFAs contents raised as nitrogen concentration increased.However,within the range of nitrogen concentration from 1.38 to 5.52 mmol·L-1,the EPA and PUFAs contents decreased with nitrogen concentration increased.Conclusion The EPA output of P.pyrenoidosus CCMP 2078 could be increased when the urea concentration of 1.38 mmol·L-1 was adopted.