一株富含碳水化合物微藻的筛选和分子鉴定

微藻生长快,单位体积碳水化合物产率高,是发酵生产生物乙醇的理想原料。本研究采用通气培养系统,对初筛得到的10株微藻进行分批培养,以单位体积碳水化合物产率为主要指标,筛选富含碳水化合物的优良藻种。研究结果显示：10株微藻的生物质干重、可溶性糖含量、碳水化合物含量和碳水化合物产率变化范围分别在0.922~1.965 g/L、4.42%~19.23%、26.8%~60.9% 和36.17~149.67 mg·L-1·d-1之间,其中藻株GZ-57的碳水化合物产率和可溶糖含量最高,分别为149.67 mg·L-1·d-1 和19.23%,表明藻株GZ-57是一株具有培养潜力的高产碳水化合物微藻。进一步对其进行形态特征及基于18S rDNA、ITS序列的分子系统学分析,发现藻株GZ-57与栅藻科（Scenedesmaceae）链带藻属（Desmodesmus）的极大链带藻（Desmodesmus maximus）亲缘关系较近,因此将其鉴定为极大链带藻（Desmodesmus maximus）。

Selection of a Carbohydrate-rich Microalgae and Its Molecular Identification

Microalgae are an ideal raw material for bioethanol production because of fast growth and high carbohydrate productivity, Ten pre-selected microalgae strains were cultivated in an air-bubble column photobioreactor to test the characteristics of carbohydrate production, and carbohydrate productivity was used as the key parameter to select the strains suitable for carbohydrate production. Results showed that biomass, soluble sugar content, total carbohydrate content and carbohydrate productivity of the tested strains were in the range of 0.922 - 1.965 g/L, 4.42% - 19.23%, 26.8% -60.9% and 36.17 - 149.67 mg·L-1·d-1, respectively. Both carbohydrate productivity （ 149.67mg·L-1·d-1） and soluble sugar content （19.23%） of GZ-57 were the highest among the investigated strains, and GZ-57 was selected as the candidate strain with greatest potential in bioethanol production. Morphological observation and molecular phylogenetic analyses of 18S rDNA gene sequences and internal transcribed sequences （ITS） indicated that GZ-57 belonged to the Desmodesmus genus, and was identified as Desmodesmus maximus.