Biofilms in… Extraterrestrial Life

Finding even the tiniest life forms out of our planet Earth is extremely exciting. Microorganisms are spread throughout many ecosystems, living under a great diversity of “extreme” conditions (e.g. very high or low temperatures, anaerobic environments, desiccation, etc.). This ability makes these organisms potential candidates for living under extraterrestrial atmospheres, as it is reasonable to believe that life may occur under earth-like extreme conditions (as some planets or other celestial bodies might provide), favoring the establishment of microbial communities in the form of biofilms as long as there is liquid water present.

Some of the celestial bodies in which microbial life possibilities have been addressed are Mars, Venus, Jupiter’s Moon Europa and Saturn’s Moon Titan. From different Martian meteorites found in Antarctica, Nakhla (Egypt) and Shergotty (India), among others, it has been controversially claimed that some nanobacterial specimens have been found; however, as of today the confirmation of the origin of this microbial life in meteoritic structures has not been yet confirmed.

The bacteria-like forms in Nakhla
Reproduced from Reproduced from NASA website.

Proposals of microbial life in Europa are based on the existence of a salty liquid ocean (placed under an ice layer of approximately 100 km thickness), based on comparisons with analysis in Antarctica obtained from Vostok station, which showed microbial presence at approximately 4 km underneath a heavy salty ice layer. Venus as a candidate is weak considering its high temperature and pressures, but due to the recent detection of water in this planet (2000), hope for extraterrestrial life in the form of microbial biofilms has stand.

Electron microscope image shows tubular structures of martian origin that may be fossils of organisms.
Reproduced from NASA website.

Intrepretation of biofilm fossils has been one of the tools for the identification of traces of microbial life. These studies include characteristic morphologies examination, biomarkers usage, microarray essays, and isotopic fractionations, among other techniques. Modern Astrobiology requires an improvement on the usage of these techniques and investigations in new ones (with in-situ surface analysis techniques, biological culture and non-culture dependant techniques for identifying DNA traces and possible microbial growth, etc.), in order to have higher degree confidence and provide unambiguous evidence for having conclusive proofs about biofilms extraterrestrial life and its origin. Achieving this is not exactly easy, tho.

So far, if the evidences of fossils associated to microbial life are confirmed, there is an indication of the existence of environments others than Earth’s suitable for microbial niches establishment, which could lead to realistic future possibilities for higher organisms life outside our planet. Carl Sagan (1961) and Friedmann and Ocampo-Friedmann (1995) had even proposed the usage of cyanobacteria in Venus and Mars, respectively, in order to enhance temperature modifications with the ultimate goal of enhancing habitats fit for human existence outside our planet (for which there is the need of first overcoming other issues).

Extraterrestrial life in the form of biofilms, should it be detected, may not only hold the key to the origin of life on our planet Earth, but also hold the possibilities of extravagant planet engineering by using microbes as hostile atmosphere conditioners by photosynthesizing to produce oxygen, climate temperatures suitable for humans profit, and slowly make other planets comfortable for human kind.

Some recommended readings and references:

Krumbein W. E., Paterson D. M., Zavarzin G. A. (Eds) (2003). Fossil and Recent Biofilms: A Natural History of Life on Earth, Kluwer Academic Publishers, ISBN 1-4020-1597-6.
Sagan C. (1961). Science, 133:849-859.
Friedmann I. E., Ocampo-Friedmann R. (1995). Adv. Space. Res., 15:243-246.
Westall F., et al., Biofilms as Biomarkers in Terrestrial and Extraterrestrial Materials, NASA.
NASA website, Possible Life on Mars
David McKay (NASA), Interview

~ by koxinelle on April 21, 2007.