| 摘要: |
| 采用生化分析方法研究了海洋微藻Chlorella sp.1061色素、极性脂及其脂肪酸组成特点。结果表明，Chlorella sp.1061色素、极性脂及其脂肪酸组成均与小球藻属的其它藻类存在着很大差异。绿藻纲中的主要化合物，如叶绿素b、十六碳四烯酸[16：4(n-3)]和亚麻酸[18：3(n-3)]均未在Chlorella sp.1061中检测到。从Chlorella sp.1061中分离到占总极性甘油脂8mol％的甜菜碱-1，2-二酰基甘油-0-4'-(N，N，N-三甲基)高丝氨酸(DGTS)，并从半乳糖脂和DGTS等极性甘油脂中检测到大量的二十碳五烯酸[20：5(n-3)](EPA)。但是一般认为，小球藻属藻类中不含这两种化合物。根据Chlorella sp.1061的这些特点，作者认为它不应该被归到小球藻属中。由于Chlorella sp.1061在色素、极性甘油脂及其脂肪酸组成特征方面与大眼藻纲(Eustigmatophyceae)中的拟微绿球藻(Nannochloropsis)非常相似，因此，Chlorella sp.1061可能是Nannochloropsis中的一个种。 |
| 关键词: 海洋小球藻,化学分类,脂肪酸,叶绿素b，1，2-二酰基甘油-0-4'-(N，N，N-三甲基)高丝氨酸 |
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| 基金项目:国家重点基础研究发展规划项目资助，G1998010100号；国家自然科学基金项目资助，30270337号 |
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| LIPID CHARACTEIRISTICS AND TAXONOMIC IMPLICATION OF MARINE MICROALGAE SHLORELLA SP．1061 |
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FENG Fu-Ying1, YANG Wen1, LIN Wei2, JIANG Gui-Zhen1, XU Yi-Nong1, KUANG Ting-Yun1
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1.Key Laboratory of Photosynthetic and Environmental Molecular Physiology，Institute of Botany，Chinese Academy of Sciences;2.Key Laboratory of Marine Experimental Biology，Institute of Oceanology，Chinese Academy of Sciences
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| Abstract: |
| Chlorella species, unicellular common green algae, are wildly distributed in different waters (fresh water and sea), soil and air. Because of easy cultivation and (or) enriched bioactive products, some are used as models for the study of plant metabolism and function. Researchers on Chlorella face many problems caused by unclear traditional classification of Chlorella. As morphological characteristics are few, it is difficult to classify Chlorella cells correctly using traditional taxonomic methods. Chemotaxonomy is therefore an importance alternative in algae classification. Chemotaxonomy classification is based on internal differences in chemistry including pigments, fatty acids, lipids, protein and nucleic acids.
One marine strain, identified as Chlorella sp. 1061, is widely used in China as feed for rotifers and brine shrimp. Unlike bright green color in other Chlorella strains, Chlorella. sp. 1061 is dull yellow-green indicating that Chlorella sp. 1061 may have distinct pigments. Differences are also seen in fatty acids. Chlorella sp. 1061 contains higher amounts of EPA than other Chlorella strains do. Therefore, the taxonomic position of Chlorella sp. 1061 is questionable.
On the other hand, although Chlorella sp. 1061 is widely cultivated in China with high potential commercial value of high amount of EPA, few physiological and biochemical data is available. Considering collectively the pigment, polar glycerolipids, fatty acid and membrane lipid of Chlorella sp. 1061, the taxonomic position of Chlorella sp. 1061 should be reconsidered.
Pigment composition of Chlorella sp. 1061 was analyzed by HPLC, 6 special peaks were identified according to retain time of standards indicating 6 pigments. TLC and GC were applied to characterize membrane lipids and fatty acids of this alga.
Marine microalga Chlorella sp. 1061 has been traditionally placed below class Chlorophyceae, order Chlorococcales and genus Chlorella, yet the chemical analysis results has revealed that Chlorella sp. 1061 were largely distinguished in biochemistry from other Chlorella. In Chlorophyceae, Chlorophyll b is one of the major photosynthetic pigments; and 16:4(n-3) and 18:3(n-3) are the major fatty acids. However, these compounds have not yet been detected in Chlorella sp. 1061 that contains no other chlorophyll but chlorophyll b, and no phycobilins. As we know, only members of Eustigmatophyceae were found to have the biochemical characteristics. Also Eustigmatophyceae members can produce a relatively high content of betaine lipid diacylglyceryhrimethylhomoserine (DGTS) eicosapentaenoic acid[20:5(n-3)]. Chlorella species, however, are thought to be unable to produce DGTS and 20:5(n-3), and yet both were found in Chlorella sp. 1061. DGTS level amounted to about 8 mol% of total polar glycerolipids while Eicosapentaenoic acid, the major fatty acid in this alga, was mainly distributed in monogalactosyldiacylglycerol(MGDG), diagalactosyldiacylglycerol(DGDG), DGTS, and phosphatidylglycerol(PG). All these results all suggest that Chlorella sp. 1061 is not a member of the genus Chlorella, but rather belongs to Eustigmatophyceae, perhaps Nannochloropsis sp. |
| Key words: Marine Chlorella, Chemotaxonomy, Fatty acids, Chlorophyll b, Diacylglyceryltrimethylhomoserine(DGTS) |
