尿素浓度对粉核油球藻Pinguiococcus pyrenoidosus CCMP 2078生长和二十碳五烯酸积累特性的影响

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

目的探索不同尿素浓度对粉核油球藻（Pinguiococcus pyrenoidosus CCMP 2078）生长、脂肪酸组成、二十碳五烯酸（EPA）和多不饱和脂肪酸（PUFAs）含量的影响。方法采用GC-MS测定脂肪酸组成和含量。结果以尿素为氮源,氮浓度低于0.069 mmol.L-1时,藻几乎不生长;氮浓度为1.38 mmol.L-1时的细胞密度、干重和比生长率最高,随氮浓度继续升高,藻生长受到明显抑制。不同氮浓度条件下的脂肪酸组成不同。氮浓度为1.38 mmol.L-1的培养条件下,粉核油球藻的EPA和PUFAs含量最高,分别为15.66%和28.65%。在0.0069~1.38 mmol.L-1的氮浓度范围内,EPA和PUFAs含量随着氮浓度的增加而上升;而在1.38 mmol.L-1~5.52 mmol.L-1的氮浓度范围内,EPA和PUFAs含量随着氮浓度的增加而下降。结论采用1.38 mmol.L-1的尿素浓度进行藻的培养可以提高粉核油球藻P.pyrenoidosus CCMP 2078的EPA含量。

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.