[H-CG30] Closed bio-ecosystems in extraterrestrial environments

[HCG30-04] Free amino acid composition of a terrestrial cyanobacterium Nostoc sp. HK-01
-Cyclical utilization as food resources in space-

*Midori Ong¹, Yasuko Kimura², Shunta Kimura¹, Kaori Tomita-Yokotani¹ (1.University of Tsukuba, 2.Jumonji University)

Keywords:A terrestrial cyanobacterium Nostoc sp. HK-01, Analysis of amino acids, Space food resources

The terrestrial cyanobacterium Nostoc sp. HK-01 is a photosynthetic and nitrogen-fixing microorganism capable of tolerating harsh environmental conditions. Though Nostoc sp. HK-01 reportedly has a high nutritional value and produces high levels of proteins, the amount of free amino acids it produces has yet to be analyzed. Amino acids build proteins and play important roles in supporting life activities of humans. In this study, we aimed to analyze the amount of free amino acids in Nostoc sp. HK-01. Nostoc sp. HK-01 produces extracellular substances (ES) to protect itself from UV radiation and dryness. We quantified the intracellular and extracellular free amino acid content of Nostoc sp. HK-01 using extracts derived from dried colonies. We investigated the change in the amount of free amino acids after UV exposure, to determine whether UV radiation could be used in the space environment. We found that Nostoc sp. HK-01 produces 17 amino acids that make up human proteins, and that the amount of extracellular amino acids increased after UV exposure. We have discussed the method for its cyclical utilization as a food resource in space under a closed environment, based on the free amino acid composition in Nostoc sp. HK-01.