Awardee: James A. Bradley (University of Southern California)
Current Placement: Assistant Professor, Queen Mary University of London
Degree: Ph.D. Geographical Sciences, University of Bristol (2016)
Advisor: Douglas E. LaRowe (University of Southern California)
Amount: $215,428.63
Award Dates: October 10, 2016 — March 31, 2019


Microorganisms buried in marine sediments endure prolonged energy-limitation over geological timescales. My research within C-DEBI is motivated by the quest to determine and understand activity levels among microbial communities in the marine subsurface in relation to their geochemical and physical environment. To this end, in collaboration with Doug LaRowe and Jan Amend (USC), I developed novel modelling frameworks based on thermodynamic and microbial-modelling principles to explore and quantify:

  • The energy sources to deeply buried microorganisms and their demand for energy.
  • The activity of microorganisms and the factors that determine physiological transitions between active and dormant states.
  • The varying energy requirements of active and dormant microbes and the allocation of energy between maintenance and growth.
  • The cell-specific energy utilization (i.e. power) of subsurface life on a global scale.

I led the development of a new freely-available and open-source platform MicroLow 1.0 – a process-based microbial model that explicitly considers physiological state transitions and energy for maintenance and growth. Using this model, I showed that energetic efficiency provides a selective advantage for long-term microbial survival in oligotrophic marine sediments.

Numerous additional opportunities have arisen thanks to the C-DEBI program and community, including participation in two collaborative workshops (organic carbon preservation, impacts of deep sea mining), numerous valuable interactions, ongoing collaborations and spin-off projects, presentations at international conferences, professional development opportunities, media exposure, complementary funding including a Deep Carbon Observatory DLMV Fellowship, significant widening of my professional network, fieldwork opportunities, and career progression.