Increasing lipid content of microalgae
Overexpression of GmDof4 from Soybean Significantly Enhances the Lipid Content of Chlorella ellipsoidea
Microalgae are considered to be a possible source to produce biodiesel, the succedaneum of fossil fuels . Many attempts have been taken in increasing lipid content of microalgae  by biochemical and genetic engineering . The significant accumulation of lipid of microalgae had been achieved using the biochemical engineering, such as nitrogen starvation , but the cell growth is severely limited . However, the improvement of lipid content in microalgae by genetic engineering is rare . Chlorella ellipsoidea, an unicellular eukaryotic green alga, has higher cell growth rate but lower lipid content (15%) , compared with the microalgae with high lipid content. Here we transferred GmDof4 from soybean (Glycine max), a transcription factor affecting content of lipid in Arabidopsis, into C. ellipsoidea and found that the expression of GmDof4 significantly enhanced the lipid content by maximum 57.21%, shifted the content of different fatty acids, but did not affect the growth of the host cells. Using the Solexa/Illumina-based RNA-Seq analysis, we found expression of the GmDof4 significantly regulates 1,076 genes, of which 754 genes was up-regulated, and 322 genes was down-regulated under mixotrophic culture. This study provides a new way in improving the lipid of microalgae.