Quasi-mechanistic photosynthetic unit (PSU)-model for the simulation of light-dependent stationary photosynthetic kinetics

The main objective of this work was to improve the existing PSU-Model of Han* (2002) and to develop a quasi-mechanistic PSU-model capable of bridging the gap between the physiological photosynthesis models and the process-oriented photosynthesis models, which often are purely empirical or based on the PSU-concept. For this purpose, the photosynthetic electron transfer chain (ETC) was modelled as a series of two consecutive limiting steps (the kinetics of the reaction center II (RCII) and RuBisCO, respectively), which are connected via the plastoquinone (PQ)-pool. The PQ-pool also acts as a buffer between the two limiting steps. The steady-state oxygenic photosynthetic rate is assumed to be proportional to the reaction rate of PQ-oxidation. In this work, the microalgae Chlorella vulgaris was used as a model organism.

The PSU-model presented here was developed as part of the author’s PhD program between 2018-2022 at the Institute of Process Engineering in Life Sciences – Bioprocess Engineering of the Karlsruhe Institute of Technology (KIT). The PhD program was supervised by Prof. Dr.-Ing. Clemens Posten.

*: Han, B.-P. (2002): A mechanistic model of algal photoinhibition induced by photodamage to photosystem-II. In: Journal of theoretical biology 214 (4), S. 519–527. DOI: 10.1006/jtbi.2001.2468.