This title appears in the Scientific Report : 2013 

Phenotyping Nannochloropsis gaditana under different conditions in controlle photobioreactor in laboratory and upscaled photobioreactors in greenhouse
Braun, Regina (Corresponding author)
Pflanzenwissenschaften; IBG-2
Jülich Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag 2013
177 S.
Dissertation, Universität Düsseldorf, 2013
Dissertation / PhD Thesis
Sustainable Bioproduction
Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment 221
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Since resources of fossil fuels are limited, alternatives for energy production need to be explored. Besides plants as biomass and energy crops, the interest in microalgaehas been increasing, as they can synthesize many valuable compounds with a large application range, including transport fuels or fish and animal feed, without competing with agricultural food production for arable land. Moreover, microalgae can utilize ue gas from industrial emissions and municipal wastewater as a nutrient source. For economically viable production of algae, however, it is necessary to explore the maximal potential of algae by optimized cultivation conditions and targeted genetic modifications based on the knowledge about their physiology as well as regulatory mechanisms of growth and metabolic processes, in addition to technical improvement of photobioreactors (PBRs) and downstream processes. Circadian clocks synchronize certain physiological, metabolic and developmental processes of organisms with specific phases of recurring changes in their environment, e.g. day and night or seasons. In this study it was investigated whether the circadian clock plays a role in regulation of growth and chlorophyll accumulation in $\textit{Nannochloropsis gaditana}$, an oleaginous marine microalga that is considered as a potential feedstock for biofuels and for which a draft genome sequence has been published. Optical density (OD) of $\textit{N. gadinata}$ culture was monitored at 680 and 735 nm under 12 h/12 h or 18 h/6 h light-dark (LD) cycles and after switching to continuous illumination (LL) in controlled PBRs in the laboratory. In parallel, chlorophyll fluorescence was measured to assess the quantum yield of photosystem (PS) II. Furthermore, to test if red- or blue-light photoreceptors are involved in clock entrainment in $\textit{N. gaditana}$, some of the experiments were conducted by using only red or blue light. Growth and chlorophyll accumulation were confined to light periods in the LD cycles, increasing more strongly in the first half than in the second half of the light periods. After switching to continuous light, rhythmic oscillations persisted (especially for OD$_{680}$) at least in the first 24 h, with a 50% [...]