In this study we investigated the influence of non-photochemical quenching (NPQ) – as essential photoprotection mechanism - under different dynamic light conditions on growth and biomass development and absorption properties in the diatom Phaeodactylum tricornutum. Therefore, we co-cultivated a genetically modified cell line lacking the NPQ capacity together with cell lines possessing a functional NPQ. By means of Flow cytometry, the composition of the culture was monitored and quantified under different dynamic light conditions resembling natural conditions. The obtained results indicate that despite limited NPQ capacity, the diatoms still can cope with light stress, suggesting that other photoprotection mechanisms may compensate the loss of a functional NPQ. Presently we are testing further light conditions and are generating knockout lines that completely lack NPQ capacity under all conditions.

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Marc Adam Halder conducted this thesis under the supervision of Dr. Bernard Lepetit at the chair of Plant Ecophysiology in the group of Prof. Dr. Peter Kroth at the University of Constance and in the department of Plant Physiology of Prof. Dr. Christian Wilhelm at the University of Leipzig.