Titre de la dissertation: Integrating Limnospira indica in Bioregenerative Life Support Systems for Self-Sufficiency in Space Habitat through Air Revitalisation and Sustainable Food Production

Résumé de la dissertation: Ensuring sustainable food production in space is one of the major scientific and technological challenges that future long-duration missions and planetary settlements are encountering. This work focuses on the cyanobacterium Limnospira indica PCC 8005 as a promising biological component for bioregenerative life support systems, exploring its role not only as a photosynthetic oxygen producer and nutrient recycler, but also as a plant biostimulant.Through the ARTEMISS project, part of the MELiSSA project from ESA, we assessed the viability of space flight hardware to sustain L. indica in small photobioreactors over a period of 9 weeks in a semi-continuous culture set-up. After primary tests in laboratory conditions, a dedicated flight experiment was conducted aboard the International Space Station, where L. indica was tested under space conditions. This represents a critical step in assessing the hardware’s technological relevance for integration into space life support ecosystems. While these experimental deployments confirmed the operational feasibility of growing L. indica in space systems, complementary analyses were carried out to assess the impact of the space environment on its molecular composition, including proteomic, lipidomic, and polysaccharide profiling.Simultaneously, L. indica has demonstrated interesting biostimulant properties for plant growth and stress resistance, both relevant in a space farming context. Initial experiments addressed, through genomic analysis, the microbial modulation of the tomato endosphere and rhizosphere. This study revealed that L. indica-based treatments modulated microbial community composition, favoring taxa associated with plant growth promotion and stress tolerance. Concurrently, we investigated the ability of L. indica to support plant germination in sub-optimal soils, including regular gardening soil, Utah desert soil, and a Martian regolith simulant. Tomato seeds (Solanum lycopersicum) treated with L. indica extracts exhibited improved germination rates and early seedling vigour, particularly in the most extreme substrates, suggesting its utility in space farming contexts where conventional soils are absent. Lastly, we evaluated L. indica‘s efficacy in mitigating water stress, a critical constraint in both space and terrestrial cultivation. Biostimulated plants demonstrated enhanced physiological stability under hydric stress, as evidenced by measurements of stomatal conductance, transpiration, chlorophyll content, flavanol, and anthocyanin indexes. Notably, the effects were most pronounced during midday peaks in stress intensity, supporting the hypothesis that L. indica confers a protective, priming effect that enhances the plant’s adaptive response.Altogether, this project advances the understanding of Limnospira indica as a multifunctional organism with clear relevance for space bioregenerative systems and, by extension, for sustainable agricultural practices in resource-limited environments on Earth. structural requirement of the implant. To do this, an assessment of mechanical behaviors of a designed additively manufactured PLA composite has been elaborated. Firstly, a comparison between conventional and auxetic structures has been performed to study their influence on the compression and impact resistance properties. Subsequently, the light has been shed on the auxetic structure as it showed the best mechanical properties. Indeed, its extraordinary property has great potential in the field of orthopedics. Then, different parameters such as the dimension and the formulation have been tailored to choose the ideal design for PLA-based biodegradable implant.

Lieu de défense: salle Herman bâtiment BSM/ Plaine de Nimy