Single-cell analysis reveals individual spore responses to simulated space vacuum

Area of Science:

• Astrobiology
• Microbiology
• Space Science

Background:

• Outer space presents extreme challenges for life.
• Bacterial spores are model organisms for studying life's survival in space.
• Previous studies indicated vacuum kills spores, but individual spore responses remain unclear.

Purpose of the Study:

• To investigate molecular changes and survival mechanisms of individual bacterial spores under simulated space vacuum.
• To analyze the temporal germination and growth events of spores post-vacuum exposure.
• To identify key resistance mechanisms against space vacuum conditions.

Main Methods:

• Micro-Raman spectroscopy to analyze molecular changes in spores.
• Live-cell microscopy to track germination, outgrowth, and growth of individual spores.
• Simulated space vacuum exposure (~10^-5 Pa) for 10 days.

Main Results:

• Simulated space vacuum did not significantly denature spore proteins but reduced spore viability by up to 35%.
• Vacuum-treated spores exhibited delayed germination and impaired outgrowth, with some unable to grow vegetatively.
• Vacuum-exposed spores showed increased sensitivity to heat and osmotic stress.
• DNA-protective proteins and DNA repair pathways (NHEJ, BER) were crucial for vacuum resistance, especially under cyclic exposure.

Conclusions:

• Space vacuum impacts bacterial spore germination and growth, affecting their overall viability.
• Specific molecular mechanisms, including DNA repair and protective proteins, are vital for spore survival in vacuum.
• The study provides novel single-cell analysis techniques for understanding microorganism responses to space environments.