Research Summary

• Microorganisms are carried to space on the human body and in water or food. Many organisms that have been identified aboard spacecraft can cause crewmembers to become sick and put a long duration mission at risk.

• The virulence (disease causing potential) of these microbes can be significantly altered in space due to radiation and microgravity.

• The Microbe experiment will study three prevalent microbes, Salmonella typhimurium, Pseudomonas aeruginosa and Candida albicans that have been identified as potential threats to crew health based upon previous space flight missions.

• This evaluation of the effect of space flight on the gene expression and disease causing potential of these microorganisms will identify whether the risk of infection increases as a result of long-duration space flight which is important for the safety and performance during our future Lunar and Martian missions.

Description

Human presence in space, whether permanent or temporary, is accompanied by the presence of microbes. The extent of changes to microorganisms in response to space flight conditions is not completely understood. Because the length of human space missions is increasing, there is an increased risk to orbiting humans of infectious disease events occurring inflight. Previous studies have indicated that space flight weakens the immune system in both humans and animals. As astronauts and cosmonauts live for longer periods in a closed environment and using recycled water and air, there is an increase in the potential for negative impacts of microbial contamination upon the health, safety, and performance of crewmembers. Therefore, understanding how the space environment affects microorganisms and their disease causing potential is critically important for space flight missions and requires further study.

The Microbe experiment will utilize three model microbes, Salmonella typhimurium, Pseudomonas aeruginosa, and Candida albicans to examine the global effects of space flight on microbial gene expression and virulence attributes. These represent different types of bacteria and yeast. Sanitation procedures are used to eliminate Salmonella from food sent to orbit, but if some were missed, the impact on crew health could be significant. Pseudomonas has been detected as a contaminant in the water system of spacecraft, and was once a cause of crewmember infection during the Apollo era. Candida is a yeast that is present as part of the natural human flora, but has the potential for harmful overgrowth if microbial communities were to change over time in space. The experiment will be flown inside self-contained culture chambers which can be activated manually by a crewmember turning a hand crank to release growth media into the cell chamber. After 24 hours of growth at ambient temperatures, the growth will be stopped by a crewmember turning the hand crank once more. Upon landing, one third of the samples will be recovered as soon as possible and the live cells will be used immediately for the virulence studies while the remaining stabilized samples will be frozen at minus 80 degrees C. Ground analysis will focus on identifying differences in growth rates and patterns, changes in gene expression, and changes in virulence of the microbes in space compared to Earth.

By understanding the changes that microorganisms undergo in the space environment, these studies will lead to the development of novel vaccines and other novel countermeasures for the treatment and prevention of infectious diseases occurring during space flight and on Earth.

Space Applications

Results from this single flight experiment will provide important information on the threat of pathogens in the space environment, which will assist with development of diagnostic tools to monitor the atmosphere, water and surfaces for the presence of these microbes. Understanding the molecular responses of these organisms to space flight is a necessary step that will significantly contribute to development of systems that meet requirements for supplying and storing potable water that is free of microbial contaminants. Furthermore, identification of the changes caused by space flight to genes and proteins will provide novel targets for pharmacological intervention to prevent and control infectious disease, which will ultimately facilitate safe and productive long-term exploration of the Moon and Mars.

Earth Applications

By understanding the unique spectrum of microbial genetic and virulence changes induced by space flight, this experiment will yield valuable knowledge leading to advances in vaccine development and other therapeutics for treatment, prevention and control of infectious diseases on Earth as well as in space.

Operational Requirements

The microbes will be contained in the glass barrel of a Fluid Processing Apparatus (FPA). The FPA is a tube that contains 2 or 3 separate liquids in addition to the sample. The liquid can be introduced to the sample in a controlled order. The FPA is contained in a Group Activation Pack (GAP). The GAP will hold up to 8 FPAs that can be processed simultaneously. For this experiment, a total of 12 GAPs will be used, 6 for Salmonella and 3 each for Pseudomonas and Candida. For activation and termination, the crew will turn a hand crank that has been inserted onto the top of the GAP. Growth of the samples will last 24 hours before the experiment is terminated. Once the samples are on the ground and have been stabilized, they will be frozen at minus 80 degrees C then shipped to the PI laboratory. The growth of some samples will not be terminated and will be maintained as viable cultures at ambient temperature for infection studies.

Operational Protocols

The microbes, Salmonella typhimurium, Pseudomonas aeruginosa, and Candida albicans, will be contained in a Fluid Processing Apparatus (FPA). In order to activate the sample, the crew will turn a hand crank that has been inserted onto the top of the GAP which contains the FPAs. This will release the growth media into the samples initiating growth. The samples will grow for 24 hours in ambient conditions. The crew will then turn the hand crank again to introduce another media to terminate the growth. Once the samples have returned to ground, the live cells will be used in virulence studies while the stabilized samples will be frozen to minus 80 degrees C and shipped to the PI laboratory for gene expression studies.

• Article: Space flight shown to alter ability of bacteria to cause disease
• Ames Research Center - Microbe Hardware