PhD, Geomicrobiology & Biogeochemistry
RESEARCH INTERESTS
PHYSIOLOGY OF IRON-RESPIRING MICROBES
Some microbes have evolved to exploit the energy available from transformation of iron between redox states, forming and dissolving minerals in the process. Our lab studies the physiology of these microorganisms and their role in the environment. We ask questions like: Who are they? Under what geochemical conditions do they transform iron and how fast? What are the underlying mechanisms adopted to carry out this process? What are the products of such reactions? How do they co-exist, co-operate and compete?
IRON CYCLING IN PEATLANDS UNDER CLIMATE CHANGE
Peatlands store vast amounts of carbon, and any strategy to curb greenhouse gas emissions must encompass plans to maintain healthy peatlands as a carbon sink rather than a source. However, peatlands are under stress from factors such as permafrost melt, erosion, burning and peat extraction, with severe consequences for the biogeochemistry of surrounding water bodies. Our lab studies the links between iron and other biogeochemical cycles in permafrost peatlands in Sweden, Alaska and Tibet.
IRON-RESPIRING MICROBES IN ROCK WEATHERING AND SOIL FORMATION
Iron-respiring microbes have the ability to directly oxidize or reduce rock and soil minerals as a central part of their metabolism. These microbes can thus contribute to the initial breakdown of bedrock and the subsequent formation of soils. We study the influence of these rock-weathering microbes from the surface to subsurface of soils under different climatic regimes (arid desert to tropical forest) in the Chilean Coastal Cordillera.
IRON CYCLING AND WATER QUALITY IN AQUATIC HABITATS
The activity of iron-respiring microbes is coupled to numerous other biogeochemical cycles like the nitrogen and phosphorus cycles. Nitrogen and phosphorus are major contaminants from over-use of fertilizer, thus it is critical to understand the factors which control their speciation, mobility and turnover in the environment. We study the microbial coupling of nitrate reduction and iron oxidation in aquatic habitats, and the consequences of these microbial processes for water quality and greenhouse gas emissions.
THE EVOLUTION OF MICROBIAL IRON CYCLING ON EARTH
Early in Earth's history, the atmosphere was lacking in oxygen and the oceans contained high concentrations of reduced, dissolved iron. Specialized microbes known as photoferrotrophs thrived under these conditions by using sunlight for energy and Fe(II) to help fix carbon dioxide into biomass. The minerals formed in the process are thought to have contributed to the deposition of vast iron formations. We study the physiology of photoferrotrophs under conditions analagous to the early oceans in order to better understand their role in ancient biogeochemical cycling.