How do the Stressors of Interplanetary Space Affect Microbes?

Interplanetary space is a mystical, otherworldly place. Unlike our environment on Earth, organisms in space are exposed to strange conditions such as: microgravity, galactic cosmic radiation, solar UV radiation, etc. One unsettling question that microbiologists have considered is: How do bacteria respond to these different stressors? This is an important question to investigate for the sake of preserving the health of astronauts.

A Rensselaer Polytechnic Institute study led by Cynthia Collins revealed that Pseudomonas aeruginosa, a disease-inducing bacteria, flourishes in space. Compared to the Pseudomonas aeruginosa biofilms cultured on Earth, these space-cultured biofilms were greater in biomass and had more living cells. (A biofilm is a community of bacterial cells clustered together, which looks like a film-like substance to the human eye.)

In addition, another study revealed that E. coli are able to reproduce more efficiently in space. That is to say, even though the E. coli bacterial cells did not consume more nutrients than their Earth-cultured counterparts, the number of space-cultured E. coli bacterial cells was greater. E. coli has also been shown to be more resistant to antibiotics, hyperosmotic stress, and acid stress in space. Lynch et al. (2004) suggests that this could be due to changes in E. coli gene expression.

Although it appears that changes in bacteria growth and development are detrimental to the health of astronauts, not all bacteria thrive like Pseudomonas aeruginosa and E. coli. For example, Streptomyces plicatus actually fare better on Earth.

Studying how bacteria adapt to the conditions of interplanetary space has given microbiologists an insight into how bacteria respond to environmental stressors through gene expression. Although the environmental stressors in space, such as microgravity, are different from those on Earth, researchers’ newfound understanding of gene expression has terrestrial pharmaceutical applications.

Works Cited

Horneck, G., Klaus, D.M., & Mancinelli, R. L. (2010). Space Microbiology. Microbiology and Molecular Biology Reviews, 74, 121-156. doi:10.1128/MMBR.00016-09

Kaiser, Gary. (Photographer). [ca. 1999]. Gram stain of Escherichia coli. [Digital Image]. Retrieved from

Lynch, S. V., E. L. Brodie, and A. Matin. (2004). Role and regulation of σS in general resistance conferred by low-shear simulated microgravity in Escherichia coli. Journal of Bacteriology, 186, 8207-8212. doi:10.1128/JB.186.24.8207-8212.2004

Marlaire, R. D. (2013, June 24). Bacteria Sent Into Space Behave in Mysterious Ways. Retrieved from

NASA. (Photographer). [ca. 2002]. The International Space Station, shortly after undocking from the Space Shuttle Endeavour on June 15, 2002. [Digital Image]. Retrieved from

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