碳源种类及碳氮比对眼点拟微绿球藻生长密度、油脂含量和脂肪酸组成的影响

Effects of carbon source and concentration on the growth density,lipid accumulation and fatty acid composition of Nannochloropis oculata

研究了三种碳源Na2CO3、NaHCO3、葡萄糖对眼点拟微绿球藻生长密度和油脂含量的影响,实验结果表明相对于葡萄糖,无机碳源NaHCO3更利于眼点拟微绿球藻的生长。以NaHCO3为碳源,研究了在不同的接种密度、NaNO3浓度下,C/N对眼点拟微绿球藻生长密度和油脂含量的影响。实验结果表明,C/N对眼点拟微绿球藻生长密度的影响与接种密度和NaNO3浓度有关,在高的NaNO3浓度时,C/N对眼点拟微绿球藻生长密度的影响很小;在低的NaNO3浓度时,随着C/N比的增加,微绿球藻的生长密度先增加后下降,存在最佳的C/N比。最佳的C/N比随接种密度而变化,在接种密度为OD440=0.10时,最佳C/N比为3,当接种密度提高到OD440=0.70时,最佳C/N比增加到5。NaNO3浓度和C/N对微藻油脂含量均有较大影响,在不同的接种密度和NaNO3浓度下都表现为C/N=1时最利于微藻油脂的积累,这与卡尔文循环过程中核酮糖-1,5-二磷酸羧化酶/加氧酶的活性有关。本实验的最佳产油培养条件为以NaHCO3为碳源,初始接种密度为OD440=0.70,C/N=1∶1,CNaNO3=0.225g/L,此时油脂产率为56.7 mg/(L.d),EPA产率为6.5 mg/(L.d)。

Effects of carbon sources （Na2CO3, NaHCO3 and glucose） and concentration of NaHCO3 on the growth density and lipid contents of Nannochloropsis oculata were studied. N. oculata preferred inorganic carbon to glucose, the growth density and lipid content of algae cultured with NaHCO3 were higher than that with glucose. The effects of concentration of NaHCO3 on growth density and lipid content were related to inoculation density and nitrogen level. In high nitrogen level, the concentration of NaHCO3 had little effect on the growth density, but in low nitrogen level, the growth density increased at first, and then decreased with the increase of concentration of NaHCO3. Based on the results we suggest that an optimum ratio of carbon to nitrogen was existed. Furthermore, we found the optimum ratio was changed with inoculation density. The optimum ratio of carbon to nitrogen was 3 when inoculation density was OD440 of 0.10, the optimum ratio increased to 5 with 00440 of 0.70. Concentration of NaHCO3 and ratio of carbon to nitrogen had significant effects on the lipid content and productivity. Lipid content reached the highest value when the ratio of carbon to nitrogen was 1 with experimental range of nitrogen level and inoculation density. The lipid productivity was 56.7 mg/（L＇d） , and the EPA productivity was 6.5 mg/（L.d） at optimum cultivation condition with NaHCO3 as carbon source, the ratio of carbon to nitrogen at 1, the concentration of NaNO3 at 0.225 g/L, and the inoculation density with OD440 of 0.70.