Microbial Ecology of Confined Habitats and Human Health

Where ever humans live micro-organisms will populate the habitat. Not only will a specific microbe community develop but also a particular 'Mobile Genetic Elements' pool through which the microbial population can exchange information. Several studies with cosmonauts have shown that during long-term stays on the International Space Station (ISS), the number of opportunistic pathogens increased while the population of certain protective micro-organisms decreased in the skin and intestinal microflora.

Prolonged human confinement in isolated habitats, often combined with particular features of waste disposal, personal hygiene, weightlessness, high oxygen content, and conditions such as localised high temperature,and humidity, and concentrations of metabolites will influence the microflora population from the crew members and the habitat. This situation can potentially result in undesired accumulation and proliferation of microbes on structural materials of the interior of the habitat (metals, polymers) and systems of life support (water tanks, air filters, etc.), which may cause a risk for crew infection and material deterioration possibly resulting in hardware and equipment malfunctioning.

In this study the microbial population present and developing in the Mars 500 habitat will be monitored. Microbial samples will be taken from all possible reservoirs of microbes such as the atmosphere, surface, water, food, waste and greenhouse reservoirs and the crew members, at several time points during the isolation period.

Microbial food supplements will be administered to some crew members to evaluate their beneficial effect in strengthening mouth and intestinal microflora and the immune system. This will contain a probiotic bacterium of the genus Enterococcus. The supplements may also supply beneficial elements (e.g. antioxidants) to the crew that will help deal with environmental and nutritional stress during long-term space missions.

In addition, new antimicrobial chemical products will be tested to prevent microbial contamination on surfaces of the habitat. Such products may reduce biosafety risks by improving the sanitary and hygienic quality of life for the crew as well a prolonging working life of inner structural materials inside the closed habitats.

Investigating the physiological potential of the spore-forming and/or heat-tolerant isolates from closed habitats with respect to resistance against low pressure, desiccation, UV-and ionizing radiation, and oxidative stress will give insights into the potential of these microorganisms to survive spacecraft cleaning/sterilization and/or ambient Martian conditions.

The scientific information to be obtained by this protocol is essential for the design of scenarios to prevent, monitor and counteract microbial hazards for the crew during future long duration space missions, such as to Mars and to collect bioburden and biodiversity data for the development and implementation of planetary protection guidelines for manned Mars missions.

Science Team P Rettberg (DE) and F Canganella (IT) et al.