Group leaders: Kai W. Finster and Bente Aa. Lomstein

Survival, activity and diversity of microbial communities in a Mars simulation tank

Background

Water is a necessary prerequisite for life, as we know it on Earth, as water has several important chemical features that make it an ideal biological solvent. Among these features are its polarity and cohesiveness. Life originated in water, and anywhere on Earth where liquid water exists, microorganisms are likely to be found no matter what the physical conditions are. Microorganisms are found in the most hostile and extreme environments such as

• hydrothermal vents with high temperatures up to 113°C
• perma frost soils with low temperatures down to -12°C
• arctic rocks with low temperatures and desiccation
• the deep subsurface with high pressure
• the stratosphere with radiation

These extreme environments are considered analogue to extraterrestrial habitats such as Mars, where several similar environments can be found. However, the basic question concerning the presence on life on Mars is whether liquid water is present or has been present in the early history of the planet. Recent experiments on the survival of bacteria in space have been carried out with a few well-known bacterial species. These studies focus on the survival of microbes in the space environment and modeling of the potential for transfer of life between celestial bodies. Based on these experiments it has been suggested that life could be more common than previously thought and it may even be that life evolved on other planets inside or outside our solar system.

The following scenario was proposed based on these results: prokaryotes might have originated on Mars and were transferred to other planets on meteorites like ALH84001. After the transfer of these pioneer organisms to for instance Earth, they evolved into the different life forms that we know today.

It will be one of the major tasks of the coming space missions to Mars, which will be launched both by ESA and NASA, to trace life or signs of life (in the form of biomolecules). As the cost of the planned missions to Mars are extremely high, it is particularly important to test materials and theories on Earth under conditions that to our knowledge prevail on Mars.
The Danish Mars Project is a contribution to these crucial investigations.

Experimental Facility

Microbiology group

The experiments are carried out in a Mars simulation environment for biogeochemical studies constructed at the University of Aarhus. The following parameters can be controlled and manipulated independently and in combination in the experimental facility: radiation, temperature, pressure, and atmosphere composition. The simulator has a slues through which samples can be taken out or added without disturbing the ongoing experiment (for more details see "Marslab facilities").

Thus, with this simulation facility we have access to an experimental system, which allows us to work as closely as possible to Mars in situ conditions without going there. The flexibility of the simulator makes it possible to adjust our incubation parameters according to new insight on Mars conditions and consequently to be at the cutting edge of exobiological research.

Bacteria cultures from soil incubated in a Mars chamber

Our experiments contribute to understand under which conditions bacteria can survive the hostile chemical and physical conditions found on Mars today. In addition we investigate under which conditions life may proliferate. These investigations will be crucial for deciding on sites to search for life on Mars.

Objectives

In an integrated approach we investigate the following topics:

• The survival, the activity and the structure of complex microbial communities under Marsian conditions, light climate, pressure, temperature and atmosphere.
• The radiation resistance of anaerobic bacteria.
• The "survival" of biomarker molecules such as petidoglycan after exposure to Marsian conditions.
• Specific conditions, which prolong the survival of complex bacterial communities under Marsian conditions.

Participants

Contact persons	Research field
Associate Professor Ph.D. Kai Finster	Microbial diversity and physiology
Associate Professor Ph.D. Bente Aa. Lomstein	Microbial activity and biomarkers
Aviaja Hansen, Ph.D. student	Microbial diversity and physiology
Tove Mariegaard Pedersen	Microbial diversity and physiology
Rikke Holm, Technician

Funding

ESA-følgeforskning