一株产油微藻的筛选及分子鉴定

A NEWLY SELECTED LIPID-RICH MICROALGAE STRAIN AND ITS MOLECULAR IDENTIFICATION

利用通气培养系统,对10株经过初步生长筛选的微藻进行培养,以总脂单位体积产率为主要指标,筛选具有产油潜力的优良藻种。结果表明,10株微藻的生物质干重、总脂含量分别为0.8—1.6 g/L、14.8%—39.7%,总脂单位体积产率大于30 mg/(L.d)的有6株,其中藻株HY-6总脂单位体积产率达到最高的50.8mg/(L.d),是一株具有潜力的产油微藻。运用形态学特征和18S rDNA及ITS系统学分析相结合的方法对藻种HY-6进行分类鉴定。依据形态学特征,HY-6为球状单细胞,具有1个明显的蛋白核,杯状色素体周生,从而初步判断该藻株可能属于小球藻属(Chlorella)或拟小球藻属(Parachlorella);18S rDNA及ITS系统学分析表明HY-6与小球藻属分为两个不同的进化支,但与凯氏拟小球藻(Parachlorella kessleri)的亲缘关系较近,且具有较高的自展支持率,因此将其鉴定为凯氏拟小球藻(P.kessleri)。研究结果将为产油微藻资源的收集、筛选及后续研究提供基础。

Ten pre-selected microalgae were cultivated in a bubble column photobioreactor,and tested for their lipid production potential using lipid productivity as a key characteristic.The results showed that their biomass dry weights and total lipid contents ranged from 0.8 g/L to 1.6 g/L and 14.8% to 39.7%,respectively.Six strains of all investigated species had lipid productivity greater than 30 mg/（L.d）.The strain HY-6,which had the highest lipid productivity 50.8 mg/（L.d）,can be a candidate species for biodiesel production.Taxonomic evaluation of the strain HY-6 was performed on the basis of morphological observation and phylogenetic analyses of concatenated 18S ribosomal RNA gene and internal transcribed sequence.HY-6 was preliminarily identified to belong to either the genus Chlorella or Parachlorella on the basis of its morphological characteristics such as spherical single cell,one well-defined pyrenoid and cup-shaped chloroplast.Phylogenetic analyses of 18S rDNA and ITS of coccoid green algae within the Chlorella and the Parachlorella clades of Chlorellaceae further identified HY-6 as Parachlorella kessleri.