Close the Gap – Potential of Microalgal Biomass for Closed ECLSS and Future In-Situ Resource Utilization in Space

Hybrid life support systems are of great interest for future far-distant space exploration missions to planetary surfaces, e.g. Mars. By synergistically combining physicochemical and biotechnological algae-based subsystems, an essential step towards the closure of the carbon and nitrogen loop in environmental control and life support systems (ECLSS) shall be accomplished, offering a wide beneficial potential for ECLSS through the utilization of oxygenic photosynthesis: O2 and nutritive edible biomass can be formed in-situ from CO2, simple long-term storable inorganic salts and water. The wild type green alga Chlorella vulgaris strain SAG 211-12 was selected as model microorganism due to its photoautotrophic growth, nutritional value, high biomass yield, high long-term cultivation robustness and cultivation flexibility. Current research at the University of Stuttgart focuses on the fundamental investigation and optimization of xenic cultivation processes in gravity-dependent and µg-capable photobioreactor systems and upstream/downstream concepts for the later utilization of algal biomass as food supplement in space. This includes the optimization of the strain-specific cultivation parameter medium nitrogen for the increase of biomass productivity and its impact on biomass quality (determined by protein and main pigment quantification during cultivation process). The current paper discusses in general possible influences of cultivation process parameters on biomass composition and quality, presents suitable upstream treatments for xenic cultures and the potential of later “customized biomasses”, which can strongly vary in intra- and extracellular composition.