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Project 15 (phase II):

Deep EarthShape Geomicrobiology: Iron-metabolizing bacteria as a driving force in the weathering of silicate minerals


Investigator Names and Contact Info:

  • Casey Bryce (Environmental Microbiology). School of Earth Sciences, University of Bristol, United Kingdom
  • Andreas Kappler (Geomicrobiology). Department of Geosciences, University of Tübingen, Germany
  • Thomas Neumann (Geochemistry, Mineralogy). Department of Geosciences, Technical University of Berlin, Germany


Chilean Collaborators Involved:

  • Francisco J. Matus B. (Biogeochemistry / Nutrient cycles). Universidad de la Frontera, Temuco, Chile
  • Carolina Merino (Biogeochemistry, Microbiology, Enzymology). Universidad de la Frontera, Temuco, Chile




Exploring phenotype responses of bacteria isolated along a climatic gradient to varying energy availability.


supervisors: C. Bryce, A. Kappler



Abundance, distribution and activity of Fe-metabolizing bacteria during silicate mineral weathering.


supervisors: C. Bryce, A. Kappler




Weathering of iron-bearing silicate minerals along a climate gradient.

supervisor: T. Neumann



Changes in microbial Fe-cycling along a precipitation gradient.

  • Lea Sauter. University of Tübingen, Germany

supervisors: C. Bryce, A. Kappler




Changes in microbial iron bioavailability across a soil pH range and a climatic gradient.

  • Ruchen Tian. University of Tübingen, Germany

supervisors: C. Bryce, A. Kappler



Project summary:

Fe(II)-oxidizing and Fe(III)-reducing bacteria represent some of the few microbial processes which directly attack minerals during energy metabolism, leading to mineral break up, saprolite formation and the fixation of CO2 to support a wider microbial community. Despite their potentially fundamental importance, Fe-metabolizing bacteria are often of low abundance in the environment and exhibit strong metabolic flexibility, therefore their role in the soil environment must be investigated through targeted approaches. As a result of these challenges, a holistic picture of the role of Fe-metabolizing bacteria in weathering and soil formation is lacking.

In this project we will determine how the ecology of Fe-metabolizing bacteria influences, and is influenced by, the geochemical and mineralogical conditions throughout the weathering profile under different climate regimes. This will be done using deep drill cores spanning surface to bed rock which will be taken along the climatic gradient of the Earthshape study area, and complemented with laboratory microcosm experiments. In the course of this project, we aim to uncover how specialized Fe-metabolizing bacteria influence rock weathering and soil formation, and elucidate the geological, geochemical/mineralogical and climatic controls determining their weathering activity.