can easily be excised and used for transformation (Fig. 1), thus removing all plasmid backbone DNA (and possible antibiotic markers) for safe transformation. Such a vector structure can also serve as a blue-print for successful manipulation of different high value microalgae, as the pds and its mutation leading to norflurazon resistance are essentially ubiquitous. One amino acid substitution in pds makes Chlorella zofingiensis resistant to norflurazon and enhances the biosynthesis of carotenoids including astaxanthin