Quest for microorganisms existing at high atmosphere and space

Yokobori, Shinichi*; Yang, Y.*; Sugino, Tomohiro*; Kawaguchi, Yuko*; Itahashi, Shiho*; Fujisaki, Kenta*; Fushimi, Hidehiko*; Hasegawa, Sunao*; Hashimoto, Hirofumi*; Hayashi, Nobuhiro*; Imai, Eiichi*; Ito, Takashi*; Kawai, Hideyuki*; Kobayashi, Kensei*; Marumo, Katsumi*; Mita, Hajime*; Nakagawa, Kazumichi*; Narumi, Issei; Okudaira, Kyoko*; Shimada, Haruo*; Tabata, Makoto*; Takahashi, Yuichi*; Yabuta, Hikaru*; Yamashita, Masamichi*; Yano, Hajime*; Yoshida, Satoshi*; Yoshimura, Yoshitaka*; Yamagishi, Akihiko*

We isolated two novel species of the genus , one from top of troposphere () and the other from bottom of stratosphere (). Can these newly isolated bacterial species and strains survive harsher environment such as space environment and/or other astronomical objects such as Mars? To address these questions, we have analyzed the survival of these microbial species and strains under the extreme conditions. Environment at high altitude is extreme for microorganisms not only because of high UV radiation, but also other stresses such as extreme dryness. To clarify how dryness affects to the survivability of microorganisms, we examined the effects of desiccation and high humidity on survival and DNA double strand breaks (DSB) of , and spores of . They exhibited different survival rates and DSB patterns under desiccation and high humidity. Higher survival and less DSB occurred at lower temperatures. Spores of showed the highest survivability at each condition. Survivability of at desiccation condition is higher than that at the humid condition, although survivability of at desiccation condition is lower than that at the humid condition. We also tested the effects of various factors on survivability of spp. Together with tests under desiccation condition, these test results suggested that spp. which we tested can survive in space for years.