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Making microbes part of the equation – modelling dissolved organic matter remineralisation in the ocean

Apr 22, 2024, 13:15 Uhr
MARUM Seminar
MARUM seminar room 2070

Dr. Sinikka T. Lennartz

ICBM / University of Oldenburg

Marine microorganisms are the major drivers of elemental cycles in the ocean, yet they are not adequately represented in global biogeochemical models. While high-throughput sequencing methods provide a wealth of information about marine microbes, their enormous diversity as well as the molecular diversity of their substrates still pose a significant challenge to numerical modelling approaches. In the first part of the talk, I will argue that it is nevertheless important to include heterotrophic microorganisms in large scale ocean models to obtain a more realistic picture of how carbon reservoirs change under changing climate conditions. For example, seemingly millennial-scale net removal rates of marine dissolved organic carbon (DOC) can be explained by underlying microbial processes that act on much shorter time scales. These results suggest a much more variable DOC pool than previously thought, and emphasize the need to improve the representation of microbial processes in biogeochemical models. In the second part, I will provide an example of how genomic information can be leveraged for process-oriented modelling development. We used a genome-scale metabolic model of Prochlorococcus, the most abundant photosynthetic organism on Earth, to inform a numeric model of phototroph-heterotroph interactions and elemental turnover. Results indicate that metabolite-induced interactions between phototrophic and heterotrophic microbes systematically impact the production of dissolved organic matter and its stoichiometry.

Sinikka T. Lennartz
Sinikka T. Lennartz