| 摘要: |
| 本文研究了不同氮限制时间（0、1、2、4、6 d）对海绿球藻（Halochlorococcum sarcotum）和微绿球藻（Nannochloris oculata）叶绿素荧光参数、细胞密度、生物量、叶绿素含量、总脂含量以及脂肪酸组成的影响。本实验结果表明，海绿球藻的最大相对电子传递速率rETRmax和快速光曲线的初始斜率α都随氮限制时间增加而降低，而光系统II最大光能转化效率Fv/Fm、非光化学淬灭NPQ以及最小饱和光照强度Ik都有先增加后下降的趋势，各参数都在氮限制第6 d达到最小值。微绿球藻上述各参数的变化趋势均为随着氮限制时间增加而逐渐下降。随着氮限制时间增加，海绿球藻和微绿球藻细胞密度都有较小幅度的增加，分别在第5 d和第6 d达到最大值；两种绿藻的叶绿素含量均随氮限制时间的增加而降低，氮限制0 d时叶绿素含量最高，6 d时叶绿素含量最低；在氮限制第2 d时二者总脂产率都达到最大值，分别为0.021 g?(L?d)-1和0.017 g?(L?d)-1，由此可见，适合海绿球藻和微绿球藻产脂的最佳氮限制时间均为2 d。海绿球藻和微绿球藻的脂肪酸主要包括16:0、18:0、20:0、18:1n-9、18:2n-6和16:3n-3等。氮限制对海绿球藻的18:1n-9和MUFA（单不饱和脂肪酸总和）影响显著，均随氮限制时间增加而增加，而PUFA（多不饱和脂肪酸总和）含量随氮限制时间增加而降低；氮限制对微绿球藻的16:0、18:1n-9、16:3n-3、MUFA和PUFA有显著影响，随着氮限制时间增加，16:0、18:1n-9及MUFA含量逐渐增加，而16:3n-3和PUFA含量逐渐降低。本实验结果可为进一步开发海绿球藻和微绿球藻并对其进行大规模培养提供理论依据。 |
| 关键词: 海绿球藻 微绿球藻 氮限制 细胞密度 叶绿素荧光参数 总脂含量 脂肪酸组成 |
| DOI： |
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| 基金项目:山东省重点研发计划项目（2017GHY15104）；“十二五”国家科技支撑计划（2011BAD14B01） |
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| Effect of nitrogen limitation time on the growth, total lipid content and fatty acid composition of Halochlorococcum sarcotum and Nannochloris oculata |
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liangying1, jiweiwei1, shiweijie2, tianchuanyuan1, hunaixia1, yanyiyun1
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1.Ocean University of China;2.Ocean University of China，Marine Environment Monitoring Central Station of Qinhuangdao, State Oceanic Administration
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| Abstract: |
| In this research, chlorophyll contents, cell densities, the chlorophyll fluorescence parameters, total lipid contents and fatty acid compositions of the Halochlorococcum sarcotum and Nannochloris oculata were studied under different nitrogen limitation time (0d, 1d, 2d, 4d, 6d). The results showed that the maximum efficiency of photosynthesis (rETRmax) and initial slope of rapid curve (α) of H. sarcotum decreased significantly with the increase of nitrogen limitation time while the maximum photochemical efficiency of PSⅡ (Fv/Fm), non-photochemical quenching (NPQ) and the minimum saturating irradiance (Ik) of H. sarcotum tended to increase at first and then decline with the increasing nitrogen limitation time. The minimum values of all the chlorophyll fluorescence parameters of H. sarcotum in nitrogen limitation treatment occurring on day 6. For N. oculata, all the above parameters showed trends of gradual decrease with the increase of nitrogen limitation time. With the increasing duration of nitrogen limitation, the cell density of H. sarcotum and N. oculata increased slightly, reaching their maximum values on day 5 and day 6, respectively. The contents of chlorophyll in single cell of these two algae decreased with the increase of nitrogen limitation time. At the second day of nitrogen limitation, the total lipid productivity of both species reached the highest level, which was 0.021 g/(L d) and 0.017 g/(L d),respectively. Thus, the optimum nitrogen limitation time for the lipid production of H. sarcotum and N. oculata was 2 days. The fatty acids of H. sarcotum and N. oculata mainly include 16:0, 18:0, 20:0, 18:1n-9, 18:2n-6 and 16:3n-3, etc. Nitrogen limitation time had significant effects on 18:1n-9 and MUFA of H. sarcotum. The contents of 18:1n-9 and MUFA increased while PUFA has opposite trends with the increase of the nitrogen limitation time. Nitrogen limitation time had significant effects on 16:0, 18:1n-9, 16:3n-3, MUFA and PUFA of N. oculata. The contents of 16:0, 18:1n-9 and MUFA increased while the contents of 16:3n-3 and PUFA decreased with the increase of the nitrogen limitation time. The trend of these indicators changing with nitrogen limitation time provides the reference for the large-scale cultivation and exploitation of H. sarcotum and N. oculata. |
| Key words: Halochlorococcum sarcotum Nannochloris oculata nitrogen limitation cell density chlorophyll fluorescence parameter total lipid content fatty acid composition |