Starting with the goal of making microalgae a viable platform in synthetic biology, we set out to create a toolkit of standardised biological parts for use in these organisms. We chose to work with a diverse group of species that included Chlorella vulgaris, Chlorella kessleri, and Chlamydomonas reinhardtii. These species present a broad range of optimum growth conditions and metabolic profiles.

Characterised parts in our toolkit include promoters, terminators, fluorescent proteins, localisation tags, antibiotic markers, and CRISPR/Cas.

Our promoter library offers plant, fungal, and viral promoters of varying strengths for control of heterologous gene expression in microalgae. Our terminators were compared alongside a variety of these promoters. Multiple localization signals were investigated to enable a user to perform targeted gene expression. We also systematically characterised the effective concentration ranges for antibiotic use in a manner not yet seen for microalgae.

CRISPR/Cas systems have revolutionized genome engineering efforts by providing a quick and efficient means of inserting and deleting DNA from the host’s genome. Our toolkit set out to demonstrate the ability to perform targeted multi-plex genome engineering of microalgae in a manner accessible to any researcher.