The deep subsurface biosphere contains a vast proportion of Earth’s microbial life and organic carbon. In deep, energy-limited settings, microorganisms persist over extraordinarily long timescales with very slow metabolisms – constituting an important analogue to the potential for life beyond Earth. However, the subsurface is notoriously difficult to study because of its remoteness and limited access, as well as the low biomass concentrations and energy fluxes associated with microbial activity. Therefore, numerical models are pivotal in addressing how microorganisms endure, proliferate, and assemble in deep subsurface settings, and understanding the selective environmental pressures that determine energetic trade-offs between growth and maintenance activities. This PhD project provides the opportunity to work at the frontier of deep biosphere science by developing a microbially-explicit model for the subsurface. This model will provide quantitative insight into microbial and geochemical coupling in deep marine or terrestrial settings, and insight into the energetic limit of life. The project would suit a computational and numerate student with an interest in life in extreme environments, biogeochemistry, and microbial-biogeochemical modelling. Opportunities for funding include London NERC DTP and QMUL Principal’s Postgraduate Research Studentships. For further information about the project, eligibility and future application deadlines in 2019/20, please contact Dr James Bradley.