[B-BG01] Earth and Planetary Science Frontiers for Life and Global Environment

[BBG01-P08] A Simple and Easy Way to Isolate Nanoarchaea from Acidic Hot Springs

*Hiroyuki Sakai^1,2, Hiromi Omokawa³, Koichi Nakamura³, Takuro Nunoura⁴, Norio Kurosawa^1,3 (1.Department of Science and Engineering for Sustainable Innovation, Faculty of Science and Engineering, Soka University, 2.Japan Collection of Microorganisms (JCM), RIKEN BioResource Research Center, 3.Department of Environmental Engineering for Symbiosis, Graduate School of Science and Engineering, Soka University, 4.Research Center for Bioscience and Nanoscience, Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

Keywords:DPANN, Nanoarchaeota, Thermoacidophile, Sulfolobales, Terrestrial Hot Spring

Nanoarchaea (the phylum Nanoarchaeota) are ectosymbiotic microorganisms belonging to the DPANN (an acronym for the phyla Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, and Nanohaloarchaeota) superphylum. The most distinctive features of nanoarchaea are their tiny cells (< 0.5 μm in diameter) and small genomes (< 0.8 Mb in general). They are one of the smallest organisms having very limited metabolic capabilities (e.g., lack of the TCA cycle, glycolysis/gluconeogenesis, and electron transport chains). Elucidating their ecophysiology should contribute to understanding what is needed for the smallest life on the earth. So far, only five strains of nanoarchaea have been reported. All of them are obligate symbionts depending on a single host species. More than 20 years have passed since the first report of the cultivation of nanoarchaea by Huber et al. in 2002. However, their ecophysiology is still largely unknown. How do they interact with host species? What are their roles in natural environments? Do they affect the growth of host species negatively or positively (parasitic or mutualistic)? Are they important to the geochemical cycle on the earth? To answer these questions clearly, cultivation is the most robust tool even in this metagenomic era. Establishing easily cultivable strains must contribute to elucidating their ecophysiology. Recently, we have isolated four strains of nanoarchaea (with its host) from an acidic hot spring located in Kirishima, Japan. The procedures for the isolation of these nanoarchaea were quite simple. We used enrichment culture, 16S amplicon analysis, qPCR, and dilution to extinction method. In this poster, we will share how we isolated these four nanoarchaeal strains, as well as their physiological and genomic features.