Hey!
I’m Jan, a geomicrobiologist in the Geomicrobiology group. I’m fascinated by how microorganisms shape their environment—and how they, in turn, are shaped by it. Microorganisms have existed on Earth for billions of years, long before oxygen played a major role in our atmosphere. Then as now, many of them can live without oxygen by relying on anaerobic metabolic pathways.
In the ocean, these “two worlds—oxic and anoxic”—meet: in the water column, for example in the Baltic Sea or the Black Sea, and especially at the boundary between seawater and sediment. At and beneath this interface, key elemental cycles operate, including those of nitrogen, iron, manganese, sulfur, and methane. Many of these processes are catalyzed by microorganisms that have evolved remarkably efficient strategies to gain energy even in extremely energy-limited environments.
A major focus of my research is sulfur-oxidizing microorganisms. They use hydrogen sulfide (H₂S)—a compound that is toxic to us—as an electron donor and oxidize it to sulfate (SO₄²⁻), which is abundant in seawater. Sulfur oxidizers are highly innovative: some grow exceptionally large to store compounds; others are long and electrically conductive; some are excellent swimmers—and some can even use insoluble metals to drive the oxidation of H₂S.
Through their activity, they influence not only the sulfur cycle, but also other biogeochemical processes—including cycles that may appear less “redox-active” at first glance, such as phosphorus cycling.
Currently, within the S2B (Shore 2 Basin) research group, I investigate the coupling of sulfur and phosphorus cycling in coastal sandy sediments of the Baltic Sea. Sulfur-oxidizing microorganisms are at the center of this work. To understand their impact from micrometer scales to whole ecosystems, I combine field observations, laboratory experiments, cultivation and isolation of key organisms, and molecular approaches. My goal is to unravel—across scales—the central role these microorganisms play in controlling element fluxes and shaping environmental conditions in marine habitats.