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[AOS11-P01] A Study of Oxygen Generation Biome using Cyanobacteria with Sustaining and Circulation model by Nitrite bacteria and Nitric bacteria
Keywords:Human spaceology, Cyanobacteria, Nitrite bacteria, Nitric bacteria, Oxygen Generation Biome, Bioreactor
While Earth is currently the only planet with a sustainable environment for humans in our solar system, human spaceology, which is a study that expands human habitability to outer space, has delved into the possibility of human survivability on other planets and the moon. The International Space Station (ISS) is located 400km above the surface of the Earth and is a huge lab in which astronauts have been living for about 6 months as an experiment in human space exploration. On the ISS, water and air are as important as on the ground, and in addition to regular replenishment of water and oxygen, the life support system maintains the environment by recycling water from urine and sweat, removing carbon dioxide, and generating oxygen through electrolysis of recycled water. In addition, the Artemis program has been an ongoing project that hopes to achieve manned space exploration and long-term residence on the Moon, and even Mars. The generation of drinking water and oxygen for respiration using lunar water resources will be studied on-site in the program.
While this space habitation research are conducted, Yamashiki et al. anticipate a human migration to the Moon and Mars, which could become a reality in the latter half of the 21st century. To achieve this, they defined Earth’s ecosystem and extracted the elements that make up the “core biome” which are the minimum elements necessary for life on other planets.(1). In this concept, they developed the goal of establishing space migration to other planets by integration of the three core concepts, defining the minimum selected biome required for migration, the core technology, and the core society. As one of the core technologies, the operation of life support systems is essential for human survival in space, which requires air containing oxygen, carbon dioxide removal, water recycling, and a food supply. Currently on the ISS, the generation of oxygen, removal of carbon dioxide, and recycling of water are carried out using electrochemical reactions by certain instruments, while in the Earth's ecosystem, these are maintained naturally by the biome of bacteria and plants. For human migration to the Moon and Mars to become a reality, we consider that human life will be sustained with bacterium and plants that are of a selected biome. On the other hand, maintaining this selected biome is also a challenge, because biomes are composed of organisms as well as the human needs to take in and maintain nutrient sources.
In this study, we aim to select species that generate oxygen and remove carbon dioxide, which are important for sustaining human life, in a confined setting. We first selected cyanobacteria, which are photosynthetic bacteria that perform oxygen-evolving photosynthesis. In previous studies using cyanobacteria as bacteria for oxygen generation, the culture medium needed to be periodically added to maintain the level of nutrients necessary for culture. Therefore, maintaining this in a confined setting has not been achieved. As for nutrients, nitrate and phosphate are necessary, but assuming a closed space that includes humans, we believe that components found in urine could be utilized. By co-culturing a species that could convert urea in urine to nitrate, we believe it is possible to construct an oxygen-producing reactor that maintains culture without adding nutrients to the culture medium. Therefore, we selected nitrite bacteria with urease activity as the biological species. By co-culturing with nitrate bacteria, nitrate is obtained from urine. By combining this with the generation of oxygen and removal of carbon dioxide in the biome using cyanobacteria, and the supply of nutrients from urine from nitrite bacteria with urease activity and nitrate bacteria, we aim to maintain human life in a confined setting with the selected biome. We present a selected species and circulation model of nutrition.
[1] Yosuke Alexandre Yamashiki et al. ISBN: 9784814004942, Kyoto University Press, Jul 2023.
While this space habitation research are conducted, Yamashiki et al. anticipate a human migration to the Moon and Mars, which could become a reality in the latter half of the 21st century. To achieve this, they defined Earth’s ecosystem and extracted the elements that make up the “core biome” which are the minimum elements necessary for life on other planets.(1). In this concept, they developed the goal of establishing space migration to other planets by integration of the three core concepts, defining the minimum selected biome required for migration, the core technology, and the core society. As one of the core technologies, the operation of life support systems is essential for human survival in space, which requires air containing oxygen, carbon dioxide removal, water recycling, and a food supply. Currently on the ISS, the generation of oxygen, removal of carbon dioxide, and recycling of water are carried out using electrochemical reactions by certain instruments, while in the Earth's ecosystem, these are maintained naturally by the biome of bacteria and plants. For human migration to the Moon and Mars to become a reality, we consider that human life will be sustained with bacterium and plants that are of a selected biome. On the other hand, maintaining this selected biome is also a challenge, because biomes are composed of organisms as well as the human needs to take in and maintain nutrient sources.
In this study, we aim to select species that generate oxygen and remove carbon dioxide, which are important for sustaining human life, in a confined setting. We first selected cyanobacteria, which are photosynthetic bacteria that perform oxygen-evolving photosynthesis. In previous studies using cyanobacteria as bacteria for oxygen generation, the culture medium needed to be periodically added to maintain the level of nutrients necessary for culture. Therefore, maintaining this in a confined setting has not been achieved. As for nutrients, nitrate and phosphate are necessary, but assuming a closed space that includes humans, we believe that components found in urine could be utilized. By co-culturing a species that could convert urea in urine to nitrate, we believe it is possible to construct an oxygen-producing reactor that maintains culture without adding nutrients to the culture medium. Therefore, we selected nitrite bacteria with urease activity as the biological species. By co-culturing with nitrate bacteria, nitrate is obtained from urine. By combining this with the generation of oxygen and removal of carbon dioxide in the biome using cyanobacteria, and the supply of nutrients from urine from nitrite bacteria with urease activity and nitrate bacteria, we aim to maintain human life in a confined setting with the selected biome. We present a selected species and circulation model of nutrition.
[1] Yosuke Alexandre Yamashiki et al. ISBN: 9784814004942, Kyoto University Press, Jul 2023.