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Sammendrag

The use of microalgal starch has been studied in biorefinery frameworks to produce bioethanol or bioplastics, however, these products are currently not economically viable. Using starch-rich biomass as an ingredient in food applications is a novel way to create more value while expanding the product portfolio of the microalgal industry. Optimization of starch production in the food-approved species Chlorella vulgaris was the main objective of this study. High-throughput screening of biomass composition in response to multiple stressors was performed with FTIR spectroscopy. Nitrogen starvation was identified as an important factor for starch accumulation. Moreover, further studies were performed to assess the role of light distribution, investigating the role of photon supply rates in flat panel photobioreactors. Starch-rich biomass with up to 30% starch was achieved in cultures with low inoculation density (0.1 g L−1) and high irradiation (1800 µmol m−2 s−1). A final large-scale experiment was performed in 25 L tubular reactors, achieving a maximum of 44% starch in the biomass after 12 h in nitrogen starved conditions.

Sammendrag

ABSTRACT The use of microalgal starch has been studied in biorefinery frameworks to produce bioethanol or bioplastics, however, these products are currently not economically viable. Using starch−rich biomass as an ingredient in food applications is a novel way to create more value while expanding the product portfolio of the microalgal industry. Optimization of starch production in the food−approved species Chlorella vulgaris was the main objective of this study. High−throughput screening of biomass composition in response to multiple stressors was performed with FTIR spectroscopy and nitrogen starvation was identified as an important factor for starch accumulation. Further studies were subsequently performed to assess the role of light distribution, investigating photon supply rates in flat panel photobioreactors. Biomass specific photon supply rate proved to have a strong effect on the accumulation of storage compounds and starch−rich biomass with up to 30% starch was achieved in cultures with low inoculation density (0.1 g L−1) and high irradiation (1800 μmol m−2 s−1). A final large scale experiment was performed in 25 L tubular reactors, achieving a maximum of 44% starch in the biomass after 12 hours in nitrogen starved conditions. Keywords: Chlorella vulgaris, starch, FTIR, photon supply rate, microalgae