Microalgae - the solar powered Biorefineries of the future

Why...algae?
Fossil fuel still make up about 80% of the worlds primary energy consumption – despite of solar energy reaching us in abundance! Algae (macroalgae (seaweed), microalgae and cyanobacteria) never made this mistake. They use energy from the sun to fixate CO2 while producing 50% of the oxygen we breathe. The same can be said of plants, however, there are many reasons why algae are far more useful than traditional crops: They grow much faster, fix CO2 more efficiently and don’t take up any arable land, all while bioremediating wastewater and producing a wide range of value products or bioenergy. The value products algae can provide range from biofuels to biofertilizers, bioplastics, food, feed and pharmaceutical compounds.

Engineering the perfect production stain
Gene-editing means modifying the genetic code of the algae, to e.g. change how it uses up or produces value products. However, quite often the effects of editing the genome are hard to predict. Algae are adaptable organisms that may change their entire metabolisms to compensate as soon as genetic-engineering schemes try to “force” them to produce a certain product. This is where fundamental research becomes key – understanding cellular mechanisms, safety and backup mechanisms, regulator networks – in order to enable a shift of the algae’s metabolism not towards the greatest fitness, but towards the highest productivity.

Anabaena – the multitasker amongst cyanobacterial bioproduction platforms
In my project, I worked with the multicellular, filamentous cyanobacterium Anabaena sp. PCC 7120. Vegetative cell types perform photosynthesis, while heterocysts fix atmospheric Nitrogen – a rare ability that is vital for all other organisms. Thus, using Anabaena as a bioproduction platform opens up the possibility of simultaneously producing value chemicals in vegetative cells, while fixing N2 and potentially producing H2 as a byproduct of N2-fixation, in the heterocysts.
Potential targets for a gene-editing scheme in Anabaena are Flavodiiron proteins (Flvs). Flvs are buffering systems that are extremely important during sudden bursts of illumination that would otherwise photodamage the cells. Deleting them may seem like a bad idea – however Flvs are not that crucial under moderate light conditions and their absence may free up resources that can be used for bioproduction. Since N is also of great interest for biofertilizer production, we also explored the interconnection of vegetative cell and heterocyst metabolism. The biggest discoveries we made in this studies is firstly, that the metabolisms of vegetative cells and heterocysts are far more intertwined than previously known and secondly, that a central regulator of Carbon metabolism and photosynthesis, PacR, is just as important for Nitrogen metabolism, linking C/N balancing and photosynthesis in an intricate regulatory network.

Even though fruition of this kind of work may be around more than one corner – envisioning a future where humanity is using the energy of the sun, the ingenuity of photosynthesis and the power of science to create a truly sustainable circular bioeconomy, makes it all worth it.

Elisa Werner, a Doctoral Researcher at University of Turku, received a 6000€ grant from Finnish Foundation for Technology Promotion for completing her Doctoral Thesis in 2025.