Global Oil Biodegradation in the Ocean

• Applicant: Professorin Sara Kleindienst, Ph.D.
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 326028733

Oil inputs into the sea (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 oil inputs into the sea are quite diverse, ranging from relatively well-studied large-scale pollution events (e.g. massive oil spills) to rather overlooked small-scale pollution events (e.g. discharges from ships, rivers, and run off). Surprisingly, when summarizing all sources, most significant anthropogenic oil inputs into the sea are caused by small-scale pollution events. Substantial amounts of oil might be degraded by distinct microorganisms, which have the metabolic ability to use oil-derived hydrocarbons as energy and carbon sources. The microbial key players and the metabolic pathways for hydrocarbon degradation were mainly described at natural hydrocarbon seeps but also at large-scale pollution events such as the Deepwater Horizon oil spill, while small-scale events remained largely unexplored. Other knowledge gaps regarding oil biodegradation in the ocean are the lack of quantifications of hydrocarbon degradation rates and the missing evaluation of rate-influencing factors, across contrasting geographic locations and across different oil pollution scenarios (small- to large-scale events). However, this information is crucial to estimate the fate of oil in the ocean on a global scale and to assess the magnitude of oil potentially harming the environment and living organisms. The Emmy Noether Research Group will tackle these currently largely unexplored, highly relevant topics. In a first step, the Research Group will develop and evaluate a novel, molecular-based assay for the quantification of hydrocarbon degradation rates. Subsequently, the novel assay will be applied in tandem with already established radiotracer assays, to precisely and sensitively quantify rates of hydrocarbon degradation with two independent methods in microcosm and field samples. In a second step, systematic microcosm studies simulating small- to large-scale events will be performed with seawater from polar, temperate, and tropical regions to (i.) quantify rates of hydrocarbon degradation, (ii.) determine rate-influencing factors, (iii.) identify microbial key players, and (iv.) elucidate metabolic pathways for hydrocarbon degradation. The novel-molecular and the established-radiotracer assays will furthermore be applied to field samples to quantify in situ rates at contaminated sites. In a final step, all obtained findings will be used to gain insights into estimations of oil biodegradation on a global scale and the impact of climate change.

• DFG Programme: Independent Junior Research Groups