The potential of the lichen symbiosis to cope with extreme conditions of outer space – I. Influence of UV radiation and space vacuum on the vitality of lichen symbiosis and germination capacity

作者：Jean‐Pierre de Vera, G. Horneck, Petra Rettberg, S. Ott · 发表于：International Journal of Astrobiology · 年份：2002 · DOI：10.1017/s1473550403001216 · 被引用次数：77 · 研究领域：Lichen and fungal ecology、Biocrusts and Microbial Ecology、Planetary Science and Exploration

The lichen symbiotic organisms Fulgensia bracteata and Xanthoria elegans as well as their isolated photobionts and mycobionts were exposed to conditions simulating the extreme parameters of outer space in order to assess their limits of survival, e.g. during a potential interplanetary transfer or on the surface of an extraterrestrial body. Using the space simulation facilities at DLR, the test parameters under investigation were vacuum (10−3 Pa) and ultraviolet (UV) radiation at wavelength ranges from vacuum-UV to UV-A, applied separately or in combination. An analysis of vitality was made using confocal laser scanning microscopy and LIVE/DEAD staining using FUN I or SYTOX green. Intact lichens were extremely resistant to vacuum exposure as well as to UV radiation up to doses of about 160 kJ m−2 (200<λ<400 nm). Removal of the upper-cortex structure significantly increased the sensitivity of the lichens to the space parameters: already a relatively short treatment of about 5 h and a UV dose of about 50 kJ m−2 reduced the vitality rate to nearly 50%; however, the dose effect curves levelled off and continued treatment did not reduce the vitality further. Similar survival curves levelling off at higher UV doses were observed for the isolated photobionts; however, in the latter cases, the saturation occurred at five times lower doses (full UV spectrum). Also spores of the mycobionts showed a remarkable UV (254 nm) resistance up to doses of about 3 kJ m−2. The data suggest that th...