Establishment of an efficient genetic transformation system in Scenedesmus obliquus

Scenedesmus obliquus belongs to green microalgae, which is attracting attention as a feedstock for biofuels production and biorefinery as well as in bioremediation of environmental pollutants, making its genetic modifications for more efficient growth and accumulation of aimed metabolites significant. However, the genetic transformation system of S. obliquus is still not well established. In the current work, S. obliquus was transformed via electroporation using a plasmid containing chloramphenicol resistance gene (CAT) as a selectable marker and the green fluorescent protein gene (gfp) as a reporter. Using the optimized transformation conditions, the transformation efficiency was 494±48 positive transgenic clones per 10(6) recipient cells, which is more efficient comparing with those reported in other microalgal transformation studies. Green fluorescence was observed after six months of cultivation, and CAT-specific products were also detected in the transformants by PCR, Southern blot and RT-PCR analysis. This is the first report on establishing such an efficient and stable transformation system for S. obliquus, a prerequisite for both functional genomic studies and strain improvement for other biotechnology applications of this important microalgal species.