Microalgae are a diverse group of single celled mixotrophic eukaryotes, which have far reaching impacts throughout aquatic ecosystems. Being nearly ubiquitous in both freshwater and saltwater environments, microalgae are able to produce nearly 50% of the world atmospheric oxygen and account for approximately 50% of total carbon fixation (Leon et al, 2004; Tabatabaei et al, 2010). A large portion of the carbon fixation is stored as lipids within the algae, specifically triacylglycerols and other long-chain hydrocarbons (Tabatabaei et al, 2010). Microalgae have been storing carbon in this form for 100’s of millions of years and through decomposition have left the lipids behind as fossil fuels, which we now extract and utilize on a daily basis (Radakovits et al, 2010).

With further development of efficient and predictable synthetic biology tools for microalgae, there is a potential for sustainable and economical production of their biolipids. Currently, wild type species are being harvested for this purpose, however due to certain drawbacks, including the inhibitory nature of their thick cell walls and undesirable lipid characteristics, microalgae are not always economically competitive versus traditional fuel sources (Radakovits et al, 2010).

The aim to develop an increasing library of microalgae chassis in synthetic biology will potentially increase the probability to engineer the algae to produce hydrocarbons with shorter chain lengths, which would be more suitable for fuels such as diesel, gasoline and propane.

In addition to the development of a collection of promoters and terminators, iGEM Concordia have explored two separate lipid modification mechanism genes, a thioesterase from E. coli, TesB, and a fatty acid desaturase, FAD3, from Arabidopsis thaliana. Other potential synthetic biology modifications to microalgae include direct synthesis of alkanes, lipid excretion and enhanced photosynthesis (Radakovits et al, 2010).

Chlamydomonas reinhardtii was used for experimental validation of our synthetic biology toolkit for a variety of Chlorella species. Chlorella spp. were chosen as our chassis because of their ability to produce a variety of valuable metabolites, natural high lipid content, quick growth rate, and ability to express a variety of eukaryotic genes from both the plant and animal kingdom.

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