营养盐初始组合浓度对类波氏真眼点藻生长和油脂积累的影响

为了研究培养基中主要营养元素氮、磷、硫初始组合浓度对类波氏真眼点藻(Eustigmatos cf.polyphem D.J.Hibberd)生长、油脂积累和脂肪酸组成的影响,分别以NaNO_3、K_2HPO_4、MgSO_4为氮、磷、硫源,设置不同的营养盐初始组合浓度对其进行培养,采用干重法、重量法、气相色谱分析法、元素分析仪等依次对生物量、总脂、脂肪酸组成和细胞内元素含量进行测定。结果显示,氮、磷、硫三者的初始组合浓度变化对类波氏真眼点藻的生长和油脂积累具有明显的影响,9 mmol/L NaNO_3、0.92 mmol/L K_2HPO_4、0.3 mmol/L MgSO_4营养条件下其生物量达到最大值,为9.19 g/L;低氮、低磷胁迫或二者共同胁迫均促进其油脂积累,但低硫胁迫对油脂的积累影响不大,最大油脂含量出现在3 mmol/L NaNO_3、0.029 mmol/L K_2HPO_4、0.3 mmol/L MgSO_4条件下,为68.7%(DW)。此外,类波氏真眼点藻富含棕榈油酸,占总脂肪酸含量的最大值达60.88%。选择合理的氮、磷、硫初始组合浓度能够有效促进其生长或油脂及棕榈油酸的积累。

Effects of initial combined concentrations of nutrients on the growth and lipid accumulation of Eustigmatos cf. polyphem

To determine the effects of different initial combined concentrations of N, P and S on the growth, lipid accumulation, and fatty acid compositions of Eustigmatos cf. polyphem D. J. Hibberd, we cultivated the algae in modified BG-11 medium containing different combined concentrations of nutrients (sodium nitrate, dipotassium phosphate, and magnesium sulfate used as nitrogen (N), phosphorus (P), and sulfur (S) sources, respectively). Biomass concentration, total lipid content, fatty acid composition, and primary intracellular nutrient element content were measured by dry weight, gravimetrics, gas chromatography, and elemental analyzer, respectively. Results showed that different initial combinations of N, P, and S significantly affected the growth, lipid accumulation, and fatty acid composition of E. cf. polyphem. The highest biomass concentration reached 9.19 g/L under 9 mmol/L NaNO₃, 0.92 mmol/L K₂HPO₄, and 0.3 mmol/L MgSO₄. Low N or P stress or combined low N and P stress promoted lipid accumulation, though there was no obvious influence on lipid accumulation under low S stress. The highest total lipid content reached 68.7% of dry weight under 3 mmol/L NaNO₃, 0.029 mmol/L K₂HPO₄, and 0.3 mmol/L MgSO₄. The E.cf.polyphem fatty acids were rich in palmitoleic acid, with relative amounts reaching 60.88% of total fatty acid. Thus, reasonable combined concentrations of N, P, and S effectively promoted growth and lipid and palmitoleic acid accumulation of E. cf. polyphem.