Visualizing the spatio-temporal dynamics of competition and cooperation with Staphylococcus aureus in nasal bacterial model communities on the cellular level

• Applicant: Dr. Jan-Samuel Puls
• Subject Area: Medical Microbiology and Mycology, Hygiene, Molecular Infection Biology ; Microbial Ecology and Applied Microbiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559616476

In the human nasal microbiome, bacteria compete for scarce resources and limited space. This environment is a key habitat for the opportunistic pathogen Staphylococcus aureus. Of special importance to S. aureus survival in the nasal microbiome are interactions with coagulase-negative staphylococci (CoNS) and with corynebacteria. These constitute two of the most abundant genera in human nasal microbiota that frequently engage with each other in competition or cooperation. These interactions include the production and consumption of iron-binding siderophores as well as the production of bacteriocins that kill or inhibit the growth of other bacteria. Research of recent years uncovered mechanistic principles and direct interaction rules of siderophores and bacteriocins that are present in bacterial communities, demonstrating their importance for bacterial survival, proliferation and competition. However, there is a lack of understanding how siderophores and bacteriocins are integrated to shape the spatial and structural dynamics of nasal bacterial communities on the cellular level. Finding answers to these open questions promises to uncover important aspects of microbial ecology. To contribute to this endeavor, this project aims to investigate how siderophores and bacteriocins impact communities of nasal staphylococci and corynebacteria, with a distinct focus on the central importance of microscale spatial structure for microbial social behavior. In a bottom-up approach, small defined communities centered on S. aureus will be spatio-temporally visualized by fluorescence microscopy to (1) characterize the impact of siderophore interactions on S. aureus, (2) elucidate the impact of bacteriocin production on nasal communities and (3) Investigate the interplay of siderophores and bacteriocins in the communities. To address these goals, the impact of siderophore cooperation and cheating by CoNS and/or corynebacteria on the ability of S. aureus to proliferate in communities will be explored. The role of microscale spatial structure in the capacity of bacteriocin production by S. lugdunensis (lugdunin, targeting S. aureus) and S. epidermidis (A37, targeting corynebacteria) to benefit their producers to the expense of their targets will be quantified and the impact of bacteriocin production on community dynamics resolved. Ultimately, it will be investigated how siderophore and bacteriocin interactions work in concert to shape communities’ dynamics and how the emerging social networks are integrated with spatial constraints. This project promises to elucidate key factors and mechanisms in microbial ecology on the cellular level and expand our knowledge about the role of spatial structure in multi-layered bacterial interactions on the microscale. It will further help to decipher the complex social networks that govern human nasal microbiome dynamics and inform rational approaches to sustainably shape it in beneficial ways.

• DFG Programme: WBP Position