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Exposure of phototrophs to 548 days in low earth orbit: microbial selection pressures in outer space and on early earth

Cockell, Charles S.; Rettberg, Petra; Rabbow, Elke and Olsson-Francis, Karen (2011). Exposure of phototrophs to 548 days in low earth orbit: microbial selection pressures in outer space and on early earth. ISME Journal, 5 pp. 1671–1682.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1038/ismej.2011.46
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Abstract

An epilithic microbial community was launched into low Earth orbit, and exposed to conditions in outer space for 548 days on the European Space Agency EXPOSE-E facility outside the International Space Station. The natural phototroph biofilm was augmented with akinetes of Anabaena cylindrica and vegetative cells of Nostoc commune and Chroococcidiopsis. In space-exposed dark controls, two algae (Chlorella and Rosenvingiella spp.), a cyanobacterium (Gloeocapsa sp.) and two bacteria associated with the natural community survived. Of the augmented organisms, cells of A. cylindrica and Chroococcidiopsis survived, but no cells of N. commune. Only cells of Chroococcidiopsis were cultured from samples exposed to the unattenuated extraterrestrial ultraviolet (UV) spectrum (>110 nm or 200 nm). Raman spectroscopy and bright-field microscopy showed that under these conditions the surface cells were bleached and their carotenoids were destroyed, although cell morphology was preserved. These experiments demonstrate that outer space can act as a selection pressure on the composition of microbial communities. The results obtained from samples exposed to >200 nm UV (simulating the putative worst-case UV exposure on the early Earth) demonstrate the potential for epilithic colonization of land masses during that time, but that UV radiation on anoxic planets can act as a strong selection pressure on surface-dwelling organisms. Finally, these experiments have yielded new phototrophic organisms of potential use in biomass and oxygen production in space exploration.

Item Type: Journal Article
Copyright Holders: 2011 Not known
ISSN: 1751-7370
Keywords: algae; bacteria; cyanobacteria; epilith; low Earth orbit; space exploration
Academic Unit/Department: Science > Physical Sciences
Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 28814
Depositing User: Karen Olsson
Date Deposited: 25 May 2011 15:33
Last Modified: 29 Oct 2013 14:26
URI: http://oro.open.ac.uk/id/eprint/28814
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