Evaluation of a Cyanobacterium, Nostoc sp. HK-01, as Food Material for Space Agriculture on Mars

Abstract

A terrestrial cyanobacterium, Nostoc sp. HK-01, is a candidate material for introduction to extraterrestrial environments, such as Mars, given its high tolerance to drought and other extraterrestrial environments. Here, we evaluated Nostoc sp. HK-01 as food for future habitation of Mars. We found that wet colonies of Nostoc sp. HK-01 after initiation survived for over 8 years on Martian regolith simulant (MRS), although they did not survive for over 105 days on medium without MRS. Total protein per 100 g of the dried colony of Nostoc sp. HK-01 was approximately 50 g. Increases in biomass proliferation in liquid or on agar medium were determined in six strains of terrestrial cyanobacteria, including Nostoc sp. HK-01, N. commune HK-02, N. commune YK-04, N. punctiforme ATCC 29133, Brasilonema sp. HK-05 and Calothrix sp. HK-06. Nostoc sp. HK-01 grew better compared to the other five strains under both conditions. Following the incubation of Nostoc sp. HK-01, the medium exhibited radical-scavenging activity. Sugar content in the medium after a 1-day incubation of Nostoc sp. HK-01 was one-sixth of its dry weight at initiation. These results indicate that, after liquid incubation, the remaining cells may be used as recyclable materials on Mars.