光合自养缺陷型小球藻的筛选及生物能源应用

Construction and Analysis of Photosynthesis-Deficient Chlorella protothecoides Mutants and Their Application in Biofuel Production

小球藻Chlorella protothecoides(C.protothecoides)是潜在的、可用于工业生产生物柴油的高产油微藻.本研究通过体外诱变的手段,获得了一株完全不能进行光合自养生长的突变体Al64.利用尼罗红染色和叶绿素自发荧光分析和电子显微镜分析细胞的亚显微结构,结果显示该突变体中叶绿体严重退化,其中类囊体膜结构缺失,导致该突变体缺乏叶绿素,无法进行光合自养生长.在富糖富氮的培养条件下,该光合自养缺陷型突变体的细胞密度和油脂含量比野生型细胞分别高5.54%和6.76%,分析还发现,该突变体产油能力为0.158 g L?1 h?1,比野生型提高12.8%.本文通过缺失光合作用突变体的构建,在异养高氮条件下实现了生物量及细胞内油脂含量的同步提高,为进一步提高微藻生产生物柴油的产量提供了新的研究平台.

Chlorella protothecoides is regarded as a promising renewable source for commercial biodiesel production. In this study, we obtained a photosynthesis-deficient mutant AL64 through chemical-induced mutagenesis. Nile red-staining, chlorophyll-autofluoresence and electron microscopic analysis indicated that chloroplast in this mutant was highly degenerated. The chloroplast thylakoid membrane was completely absent and the cells could not synthesize chlorophyll and therefore, failed to grow autotrophically by photosynthesis. In medium containing high glucose and high nitrogen, the cell density and lipid content of this mutant were 5.54% and 6.76% higher than that of wild type with oil production ability at 0.158 g L^-1 h^-1, which is 12.8% more than that of wild type. In summary, by constructing the photosynthetic mutant strain, we achieved high biomass and cellular lipid content simultaneously under heterotrophic cultivation condition with high nitrogen supply, providing a new platform to further increase the microalgal biofuel productivity.