Microbial supplements for extraterrestrial environments

Abstract

In 2025, the Artemis II marks the first crewed mission orbiting the Moon, with plans for subsequent missions landing astronauts near the lunar South Pole and NASA aims to reach Mars by the 2030s. The growing interest in space underscores the increasing importance of long-term human presence in space missions. Challenges such as human health and sustainable food preservation persist in establishing settlements on other planetary bodies. Space agencies are developing regenerative life support systems utilizing hydroponic cultivation of plants and microalgae, fueled by crew waste as fertilizers. While biological systems could sustain astronauts, the predominantly vegan diets lack essential micronutrients. To address this, integrating microbial-based food supplements into current bioregenerative systems is crucial for ensuring a balanced diet and maintaining the health of space explorers. The aim of this project is to develop an alternative food system by growing microorganisms in space-related conditions and using their biomass, or products thereof, as food supplements for space travelers on long-duration space missions, e.g. to Mars. We select and study the impact of space conditions on microorganisms that can provide useful micronutrients for future space travelers, which cannot be fully provided by vegan diets. This will be done by selecting a range of candidate beneficial microorganisms. Various options are available, including Bacillus subtilis spp., which can produce riboflavin (vitamin B2) and whose spores have already been tested on Mars analog surfaces (Cortesão et al., 2019). Limosilactobacillus reuteri could be used as supplement of riboflavin (Spacova et al., 2022) and has previously been shown to increase its production of reuterin under simulated microgravity conditions (Senatore et al., 2020). In addition, the yeast Yarrowia lipolytica is a well-known producer of essential amino acids, PUFA, MUFA, and vitamin B complexes (Jach & Malm, 2022). Final strain selection will be based on (i) their ability and efficiency to produce micronutrients, (ii) their safety and health promoting (incl. Radiation protective) properties, (iii) their ability to survive and maintain production efficiency under extreme environments, including ionizing radiation and microgravity, and (iv) their compatibility with bio-based in situ resource utilization techniques (e.g., gas or mineral sources from Martian atmosphere or regolith through biomining) to increase loop-closure. The selected strains will be stored, revived and grown in simulated Martian conditions, to test their long-term stability and preservation as food supplement source. Through international collaborations, we will test these conditions using reduced-gravity simulators, space radiation analogs, and substrates based on lysed cells of bacteria previously grown on regolith simulants, such as Chroococcidopsis sp. (Billi et al., 2021), and Anabaena sp., which has already been used to grow Bacillus subtilis from its inactivated biomass (Verseux, 2018). At the end of this 4-year PhD research project, the expected outcome is to improve the nutritional well-being of future space travelers settling on other planets, and also to generate innovative insights applicable to Earth-based fields such as biotechnology, radioprotection, and environmental science.