Survival of Akinetes (Resting-State Cells of Cyanobacteria) in Low Earth Orbit and Simulated Extraterrestrial Conditions
- 468 Downloads
Cyanobacteria are photosynthetic organisms that have been considered for space applications, such as oxygen production in bioregenerative life support systems, and can be used as a model organism for understanding microbial survival in space. Akinetes are resting-state cells of cyanobacteria that are produced by certain genera of heterocystous cyanobacteria to survive extreme environmental conditions. Although they are similar in nature to endospores, there have been no investigations into the survival of akinetes in extraterrestrial environments. The aim of this work was to examine the survival of akinetes from Anabaena cylindrica in simulated extraterrestrial conditions and in Low Earth Orbit (LEO). Akinetes were dried onto limestone rocks and sent into LEO for 10 days on the ESA Biopan VI. In ground-based experiments, the rocks were exposed to periods of desiccation, vacuum (0.7 × 10−3 kPa), temperature extremes (−80 to 80°C), Mars conditions (−27°C, 0.8 kPa, CO2) and UV radiation (325–400 nm). A proportion of the akinete population was able to survive a period of 10 days in LEO and 28 days in Mars simulated conditions, when the rocks were not subjected to UV radiation. Furthermore, the akinetes were able to survive 28 days of exposure to desiccation and low temperature with high viability remaining. Yet long periods of vacuum and high temperature were lethal to the akinetes. This work shows that akinetes are extreme-tolerating states of cyanobacteria that have a practical use in space applications and yield new insight into the survival of microbial resting-state cells in space conditions.
KeywordsCyanobacteria Akinetes Low Earth Orbit Mars environment
This work was supported by the STFC grant (PP/E001408/1). We would like to thank the European Space Agency for the flight opportunity, and the Russian Space Agency for access to the launch vehicle and facilities. Finally we would like to thank Dr Manish Patel for his help with the xenon light, and CEPSAR for the use of the Mars Simulated Chamber.
- Cockell CS, Brack A, Wynn-Williams DD, Baglioni P, Brandstatter F, Demets R, Edwards HG, Gronstal AL, Kurat G, Lee P, Osinski GR, Pearce DA, Pillinger JM, Roten CA, Sancisi-Frey S (2007) Interplanetary transfer of photosynthesis: an experimental demonstration of a selective dispersal filter in planetary island biogeography. Astrobiology 7:1–9CrossRefPubMedGoogle Scholar
- De Pater I, Lissauer JJ (2001) Planetary sciences. Cambridge University Press, CambridgeGoogle Scholar
- Hess SL, Henry RM, Leovy CB, Ryan JA, Tillman JE (1977) Meteorological results from surface of Mars—Viking 1 and 2. Trans Am Geophys Union 58:827–838Google Scholar
- Karlsson I (1999) On the germination of the akinete-forming cyanobacterium Gloeotrichia echinulata in Lake Erken, Sweden. Arch Hydrobiol Algolog Stud 94:175–180Google Scholar
- Sutherland JM, Herdman M, Stewart WDP (1979) Akinetes of the cyanobacterium Nostoc PCC7524: macromolecular composition, structure and control of differentiation. J Gen Microbiol 115:273–287Google Scholar
- Whitton BA, Potts M (2000) The ecology of cyanobacteria—their diversity in time and space. Kluwer, DordrechtGoogle Scholar
- Yamamoto Y (1975) Effect of desiccation on the germination of akinetes of Anabaena cylindrica. Planet Cell Physiol 16:749–752Google Scholar