The effects of microgravity on induced mutation in Escherichia coli and Saccharomyces cerevisiae

Area of Science:

• Astrobiology
• Microbiology
• Genetics

Background:

• Understanding the effects of spaceflight on biological systems is crucial for human space exploration.
• Previous research has explored various spaceflight factors on cellular processes, but the impact of microgravity on induced mutation frequencies requires further investigation.

Purpose of the Study:

• To investigate the influence of microgravity on induced mutation frequencies and SOS responses in bacterial and yeast strains.
• To assess whether DNA replication and repair mechanisms are affected by spaceflight conditions.

Main Methods:

• In vivo experiments were conducted during the STS-91 space shuttle mission.
• Repair-deficient and parental strains of Escherichia coli and Saccharomyces cerevisiae were exposed to DNA damage treatment.
• Cultures were maintained under microgravity, and induced mutation frequencies and SOS responses were measured and compared to ground controls.

Main Results:

• No significant differences were observed in induced mutation frequencies between space-flown samples and ground controls for both Escherichia coli and Saccharomyces cerevisiae.
• SOS responses, indicative of DNA damage and repair activity, were also comparable between microgravity and ground conditions.
• A novel experimental apparatus for culturing and freezing microbial stocks in space was successfully developed.

Conclusions:

• Microgravity does not appear to influence induced mutation frequencies or SOS responses in the tested strains at the stages of DNA replication and/or repair.
• The findings suggest that basic DNA damage and repair mechanisms in these microorganisms are robust under microgravity conditions.
• The developed space-ready apparatus facilitates future in-depth studies on microbial responses to space environments.