Abstract: Nannochloropsis has been believed to be a promising genus of microalgae, which has the potential as the feed stock for biofuels. To achieve the goal for industrial application, use of genetic modifications to improve oil-producing and growth characters is of great significance in reduction of costs. So, it is necessary to develop an efficient transformation method. Here, a vector pHB4857 that has a sh ble gene derived by Nannochloropsis β-tublin promoter and Phaeodactylum tricornutum fcpA terminator was constructed and transformed in N. gaditana CCAP849/5 by electroporation. Transformants were able to grow on 3 μg·mL^-1 zeocin. PCR detection indicated that 100% of the selected colonies were positive transformants. The efficiency was 1.25×10ˉ⁶. A Southern blot analysis verified that the sh ble gene with single or multiple copies was randomly inserted into the geneome and most of the transformants owned the intact heterologous genes. The transformants were inoculated in fresh zeocin-resistant medium every 10 days for more than seven months. The integration of heterologous gene in the host nuclear genome appeared to be stable since no sh ble gene was lost.

Key words: Nannochloropsis gaditana CCAP849/5, transformation, heterologous gene, integration