Microbial oil degradation in the ocean
Oil inputs into the oceans (estimated 1500 million liters per year worldwide) result in environmental pollution of global concern because oil contains hazardous compounds such as polycyclic aromatic hydrocarbons that can exert toxic or mutagenic effects on living organisms. The sources of anthropogenic oil inputs into the oceans are quite diverse, ranging from relatively well-studied “large-scale pollution events” (e.g., massive oil spills like the Deepwater Horizon oil spill) to rather poorly-explored “small-scale pollution events” (e.g., discharges from ships, rivers, and run off). Despite the large extent of oil inputs caused by the so-called small-scale pollution events, the rates of hydrocarbon degradation, the rate-influencing factors, the identity of microbial key players, and the metabolic pathways for hydrocarbon degradation remain largely unknown. In the DFG-funded Emmy Noether research project, we tackle these unknowns to greatly advance our current understanding of oil biodegradation during small-scale pollution events in the ocean.
Microbial nitrate reduction in an aquifer
Groundwater is an important drinking water source. However, the application of fertilizers in regions with high agricultural activity leads to the contamination of groundwater with nitrate. Nitrate concentrations in groundwater can be reduced by denitrifying microorganisms colonizing different zones of aquifers. Yet, little is known about the microbial key players involved in nitrate turnover in aquifers. In collaboration with a multidisciplinary team of scientist, we study nitrate turnover processes in the anoxic aquifer of the Ammer river and the Bronnbachquelle spring catchments (SW Germany). Using groundwater monitoring wells and by retrieving pristine rock samples through a drilling campaign, we revealed a high abundance of microorganisms that have the potential to couple the oxidation of iron and sulfur to the reduction of nitrate. Collectively, our interdisciplinary findings suggest that nitrate removal in groundwater occurs through a series of microbially driving redox transformations.
Microbial glyphosate degradation
Glyphosate is an herbicide that is used globally to kill weeds in several industrial sectors such as to clear rail lines or in private gardens. The dominant user of glyphosate, however, is the agricultural sector, especially since many crops have been genetically modified to withstand glyphosate application. Despite its global application, the impact that glyphosate has on the microorganisms that populate agricultural soils remains largely unknown. Does glyphosate disrupt any of the key processes performed by soil microorganisms such as the nitrogen cycle? Do soil microorganisms help degrade the glyphosate to reduce its persistence in the environment? Is glyphosate even accessible to the microorganisms that can degrade it? To tackle these questions, we study both individual microorganisms and soil microbial communities in the laboratory and in the environment. We investigate how these microorganisms interact with glyphosate by using molecular biological techniques coupled to chemical data and apply the findings to large-scale environmental processes.
Surfactant impacts from glyphosate application
In a new project funded by the ERC, we take a completely novel route and focus on the impacts of surfactants from glyphosate application. Glyphosate-based surfactants are the second most abundant ingredients of herbicide formulations and therefore large quantities have been and are still applied in nature. Even though glyphosate-based surfactants are considered inert, the effects of the single surfactant compounds, surfactant mixtures and surfactant-glyphosate cocktails are unprecedented. We aim at disentangling surfactant and surfactant-glyphosate impacts on microbes, biogeochemical cycles, greenhouse gas formations and the environment in general by using an innovative and interdisciplinary multiscale approach. Collectively, the data collected through our studies can influence policy decisions and, thus, impact societal health.