Tobias Pfennig | Capturing Cyanobacterial Photosynthesis - A spectrum-dependent mathematical model

Tobias Pfennig - RWTH Aachen, Germany
Homepage: www.cpbl.rwth-...
Capturing Cyanobacterial Photosynthesis - A spectrum-dependent mathematical model
Well-designed mathematical models complement experimental scientific work. The mathematical representation of reaction networks allows for a detailed and systematic investigation of the system. The network’s simplification and breakdown also give a new perspective to working on the whole organism. Cyanobacteria are of high economic value and becoming a promising tool in biotechnological production. However, not all aspects of photosynthesis in cyanobacteria could be experimentally elucidated, yet. Furthermore, despite their evolutionary bond to plants, the structure and components of photosynthetic electron transport differ with a high impact on the overall dynamics, prohibiting the usage of established plant-based models. Therefore, targeted mathematical models might be highly beneficial.
We have developed an ordinary differential equation-based photosynthesis model in Synechocystis sp. PCC 6803. It dynamically tracks the major photosynthetic processes, from light capture to electron transport and carbon fixation. Notably, we included a full-spectrum light description to mimic lab growth conditions. We used simple kinetic rate laws where no crucial regulatory mechanisms were apparent, and the model was parameterized using dedicated measurements and literature values. With our model, we can reproduce key spectrometric experiments and photosynthetic dynamics. These include the simulated redox state of electron carriers, flux through alternative electron pathways, and dynamic fluorescence signals. We also investigated alternative mechanisms for state transitions, for which no consensus exists yet. Notably, the model showed that the irradiance light color determines the distribution of metabolic control and, therefore, biotechnological targets.
With this model, we integrate systems-level knowledge of photosynthesis in cyanobacteria and provide a theoretical framework for further complex investigation.
This talk is part of the CyanoWorld online seminar series, hosted by Nicolas Schmelling and Ilka Axmann, and was held on Zoom on October 12th, 2023.
Follow Us on Twitter: / cyanoworld1