Eutrophication and AAP bacteria: changes in the contribution of AAP bacteria to microbial dynamics and carbon cycle in response to trophic status.

• Applicant: Professor Dr. Hans-Peter Grossart
• Subject Area: Microbial Ecology and Applied Microbiology ; Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550286677

Anthropogenic disturbances in aquatic environments are causing carbon cycle imbalance and eutrophication. Bacteria perform crucial roles in the seasonal succession of aquatic communities and are responsible for the transfer of dissolved organic carbon to the upper trophic levels through the microbial loop. Aerobic anoxygenic phototrophic (AAP) bacteria harvest energy from light through bacteriochlorophyll reaction centres supplying their heterotrophic metabolism, an adaptive advantage over pure heterotrophic bacteria. AAP bacteria undergo large seasonal oscillations in abundance and community composition. They are linked to phytoplankton bloom in freshwaters contributing up to 20-30% of total bacterial community. They use dissolved organic matter released by algae critically participating in the microbial loop. AAP community is driven by the availability of carbon and phosphorus, elements that condition lakes' trophic status. Here we want to study how eutrophication impacts the AAP communities and consecuently, the carbon cycle.

• DFG Programme: Research Grants
• International Connection: Czech Republic, Poland
• Partner Organisation: Narodowe Centrum Nauki (NCN)
• Cooperation Partners: Cristian Villena Alemany; Professorin Dr. Katarzyna Piwosz