Väitös (molekulaarinen kasvibiologia): M.Sc. (TUM) Elisa Werner
M.Sc. (TUM) Elisa Werner esittää väitöskirjansa ”The Network of C/N balancing, Photosynthesis and Flavodiiron Proteins in the Cyanobacterium Anabaena sp. PCC7120 - Towards Bioengineering Strategies” julkisesti tarkastettavaksi Turun yliopistossa perjantaina 5.6.2026 klo 12.15 (Turun yliopisto, Calonia, CAL2, Caloniankuja 3, Turku).
Vastaväittäjänä toimii tohtori Szilvia Tóth (HUN-REN Biological Research Centre Szeged, Unkari) ja kustoksena professori Yagut Allahverdiyeva-Rinne (Turun yliopisto). Tilaisuus on englanninkielinen. Väitöksen alana on molekulaarinen kasvibiologia.
Tiivistelmä väitöstutkimuksesta:
Microalgae - the solar powered Biorefineries of the future
Fossil fuel still make up about 80% of the world’s 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. to enhance the production of 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 and 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. Its vegetative cell types perform photosynthesis, while heterocysts fix atmospheric Nitrogen (N2) – 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 light that would otherwise photodamage the cells. Deleting them may seem like a bad idea – however Flvs are not crucial under moderate light conditions and their absence may free up resources that can be used for bioproduction. In our studies with mutants of Anabaena that did no longer carry the genes for certain flavodiiron proteins in vegetative cells, we discovered an increased hydrogen production in heterocysts, which points towards a greater interconnection of those two cell types than previously known.
Since N is of great interest for biofertilizer production, we dived deeper into the interconnection of vegetative cell and heterocyst metabolism. We found that a central regulator of carbon metabolism and photosynthesis, PacR, is just as important for Nitrogen metabolism, linking C/N balancing and photosynthesis, including flavodiiron proteins, in an intricate regulatory network.
In the future, this research hopefully will contribute to the development of Anabaena bioproduction platforms. These production platforms can be envisioned to be made of biofilms with immobilized bioengineered Anabaena cells, producing multiple value products. Immobilization comes with the added advantage of giving the fragile Anabaena filaments stability and making the separation of cells and product very easy. At the same time the Anabaena feedstock used for producing these biofilms may serve as an easily accessible fertilizer.
