不同品系杜氏藻的多相特征研究

杜氏藻(Dunaliella)是一类独特的嗜盐单细胞真核微藻, 为对该藻不同地理来源各品系间的特征进行总结及分类鉴定, 挖掘特色品系, 研究搜集国内外20株不同品系的杜氏藻, 利用PCR扩增内部转录间隔区(ITS)和细胞色素C氧化酶(cox2-3)基因, 生物信息学软件构建系统发育树对其进行分子鉴定; 形态学方法对其显微结构进行观察, 利用生理生化研究方法对杜氏藻盐胁迫下的4个代表性指标(最大光合效率、中性脂含量、β-胡萝卜素含量和3-磷酸甘油磷酸酶活性)进行了测定。结果表明, 20株供试藻均属杜氏藻属, ITS和cox2-3的系统发育结果相似, 均聚为两大簇, 各品系间亲缘关系较为接近; 成熟期的D13细胞最大, D14细胞最小并呈长颈形, 颜色以绿色或黄绿色为主, 鞭毛和眼点各异; D6和D10生长周期短, D18耐盐性最强; D7最大光合效率最高, D6和D18中性脂干重最高, D11的β-胡萝卜含量最高, D7的3-磷酸甘油磷酸酶活性最强。研究结果可为国内外杜氏藻资源的分类鉴定、特色资源的保护、开发与利用奠定基础。

STUDY ON POLYPHASIC CHARACTERISTICS OF DIFFERENT STRAINS OF DUNALIELLA

Dunaliella is a unique group of halophilic, unicellular, eukaryotic microalgae, which is widely used in industrial field because of its rich bioactive substances such as oil, β-carotene, and polysaccharides. Dunaliella resources are diverse in the world. The morphological difference of Dunaliella species is small. Therefore, their taxonomy and identification need to be improved. Dunaliella is broad-spectrum salt tolerant, but physiological and biochemical responses of different species under salt stress are different. It is necessary to excavate the unique Dunaliella strains. We collected 20 strains of Dunaliella from home and abroad. Gene sequences of internal transcribed spacer (ITS) and cytochrome C oxidase (cox2-3) were amplified by PCR. The phylogenetic trees of Dunaliella based on the two genes were constructed by bioinformatics analysis. We used morphological methods to identify their microscopic and submicroscopic structures. Four representative indexes (max photosynthetic efficiency, neutral lipid content, β-carotene content and glycerol 3-phosphate phosphatase activity) of Dunaliella under salt stress were measured via physiological and biochemical analysis. The results showed that all algae strains belonged to Dunaliella. phylogenetic analysis of Dunaliella results based on ITS and cox2-3 given similar results. The genetic relationships of 20 Dunaliella strains were relatively close. D13 cells were the largest, and D14 cells were the smallest with a long neck. The color of Dunaliella cells was mainly green or yellow-green. The numbers of Flagella and eye-spot of them were different. D6 and D10 had the shortest growth period. The most salt tolerant strain was D18. D7 had the highest max photosynthetic efficiency. D6 and D18 had the highest dry weights of neutral lipid. D11 had the highest β-carotene content, and D7 had the strongest glycerol 3-phosphate phosphatase activity. Our research lays the foundation for the taxonomy, identification, protection, development and utilization of Dunaliella resources in the world.