Microbial ecology of the deep terrestrial subsurface

Area of Science:

• Microbial Ecology
• Geomicrobiology
• Deep Biosphere Research

Background:

• Terrestrial subsurface microbial communities are as abundant as surface soils.
• These communities are sustained by chemolithoautotrophic primary production, with hydrogen as a key electron source.
• Limited knowledge exists on deep subsurface microbial ecology compared to other environments.

Purpose of the Study:

• To review the historical context and recent discoveries in deep terrestrial subsurface microbial ecology.
• To highlight the importance of understanding these communities for human activities like nuclear waste storage and carbon capture.
• To emphasize the need for multifaceted approaches to study subsurface microbial interactions and cryptic cycles.

Main Methods:

• Literature review of historical and recent research.
• Analysis of microbial community composition and function.
• Exploration of microbial interactions (syntrophic, episymbiotic, viral).

Main Results:

• Discovery of novel microbial groups (e.g., Candidate Phyla Radiation bacteria, Archaea).
• Identification of hydrogen as a significant energy source for subsurface life.
• Recognition of complex microbial interactions and cryptic cycles.

Conclusions:

• The deep terrestrial subsurface is a significant and underexplored biosphere.
• Understanding subsurface microbial ecology is vital for environmental management and energy technologies.
• Multifaceted research approaches are essential to fully comprehend this deep biosphere.