Light-induced changes in the photosynthetic physiology and biochemistry in the diatom Skeletonema marinoi

Light is a driving force behind the synthesis of biomass in photoautotrophs. In pelagic ecosystems, highly variable light strongly affects microalgae at an ecological (success and succession), molecular (acclimation, carbon allocation), photosynthetic and growth levels. Therefore, manipulation of light appears to be an attractive tool for enhancing growth of microalgae in order to extend the use of these organisms in biotechnological field. In this study, we investigate the responses of the diatom alga Skeletenoma marinoi to different growth light regimes, that induced composite acclimative patterns manifesting in strong alterations in the cell biology. Although the growth rate is dependent upon the integrated daily light dose received by the algae, we demonstrate that physiological and biochemical acclimation responds to additional light stimuli. The application of fluctuating red light on a sinusoidal blue light spectral distribution induces an increase in non-photochemical quenching and the de-epoxidation state of the xanthophyll cycle along with modifications of the metabolic state of the cells, e.g. an increase in carbohydrates, glycolipids and saturated fatty acids. Providing an unnatural square-wave light course induces drastic changes in photosynthesis, pigment and macromolecular composition of the cells.