Physiological adaptations to serpentinization in the Samail Ophiolite, Oman

Area of Science:

• Geomicrobiology
• Environmental Science
• Astrobiology

Background:

• Serpentinization of ultramafic rocks produces reduced substrates for microbial metabolism.
• Serpentinizing environments are characterized by hyperalkaline, low-carbon, and highly reduced waters, posing challenges for life.

Purpose of the Study:

• Investigate microbial persistence strategies in challenging serpentinizing environments.
• Analyze geochemical and microbial adaptations to hyperalkaline, carbon-limited conditions.

Main Methods:

• Geochemical measurements of serpentinizing waters.
• Metagenomic and physiological analyses of planktonic microbial cells.
• Correlation of metabolic potential with fluid geochemistry.

Main Results:

• Metabolic potential correlated with fluid type; anaerobic metabolism genes were enriched in hyperalkaline waters.
• Planktonic cell abundance and single-carbon compound utilization were lower in hyperalkaline waters.
• Higher substrate assimilation to dissimilation ratios in hyperalkaline waters suggest adaptation to stress.

Conclusions:

• Microorganisms in serpentinized waters display unique physiological adaptations for polyextremophilic conditions.
• Lower genome sizes and carbon oxidation states in hyperalkaline waters indicate adaptation to resource limitation.
• These adaptations are crucial for microbial survival in extreme subsurface environments.