Bacillus subtilis Spore Resistance to Simulated Mars Surface Conditions.

Area of Science:

• Astrobiology
• Microbiology
• Planetary Science

Background:

• Understanding microbial survival on Mars is critical for planetary protection and life detection.
• Bacillus subtilis spores are highly resistant and serve as a model organism for studying survival in extreme environments.

Purpose of the Study:

• To determine the survival of Bacillus subtilis spores under simulated Martian conditions.
• To identify key mechanisms and genetic factors enabling spore survival in the Martian environment.

Main Methods:

• Exposing B. subtilis mutant strains (defective in DNA protection/repair) to simulated Martian atmosphere with and without UV radiation for 24 hours.
• Analyzing spore survival rates and DNA damage accumulation under different simulated conditions.

Main Results:

• B. subtilis spores survived simulated Martian conditions, with higher survival rates in the absence of UV radiation.
• Spore survival under UV radiation depended on DNA protection (SASP) and repair mechanisms.
• Survival without UV radiation relied on spore coat protection, with DNA double-strand breaks as the primary damage.

Conclusions:

• Bacillus subtilis spores can survive limited exposure to the Martian surface.
• UV radiation is a major stressor, but shielding by materials like dust can extend spore survival.
• Further research should investigate DNA damage in wild-type spores and survival with regolith shielding.