Bioenergetic Controls on Microbial Ecophysiology in Marine Sediments.

Area of Science:

• Microbial Ecology
• Marine Geochemistry
• Bioenergetics

Background:

• Marine sediments are energy-limited habitats where microorganisms survive with slow metabolisms.
• Understanding microbial responses to energy limitation (growth, dormancy, death) is key to studying life's energetic limits.
• Existing models often overlook variable microbial physiological states and energy demands.

Purpose of the Study:

• To review existing modeling constructs for microbial growth, yield, maintenance, and physiological state.
• To present a novel numerical model integrating these factors for energy-limited environments.
• To discuss the model's application to the marine subsurface.

Main Methods:

• Review of established modeling constructs for microbial growth, yield, maintenance, and physiological state.
• Development of a new integrated numerical model.
• Discussion of model validation using biomass and biogeochemical rate measurements.

Main Results:

• A new model is proposed that incorporates variable microbial physiological states and energy demands.
• The model aims to address knowledge gaps in microbial bioenergetics under extreme energy limitation.
• The study highlights the importance of understanding cell death and energy metabolism for model design.

Conclusions:

• The developed model will advance understanding of the minimum power required to support life in marine sediments.
• It will elucidate ecophysiological strategies employed by microorganisms under prolonged energy limitation.
• The model provides a framework for future research in marine subsurface microbial ecology and bioenergetics.