Biofilm matrix assembly in Synechococcus elongatus: secretion pathways and extracellular regulation

• Applicants: Professor Dr. Alexej A. Kedrov; Dr. David A. Russo
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573774436

Cyanobacteria inhabit nearly every environment on Earth, occurring either in a suspended state or within biofilms. These biofilms are communities of cells embedded in a self-produced matrix of extracellular polymeric substances (EPS), such as polysaccharides, structural proteins and extracellular DNA. Biofilms play a vital role in cyanobacterial ecology, as their formation aids survival in hostile environments and facilitates colonization of new niches; however, systematic studies of cyanobacterial biofilms and their matrix architecture are still lacking. Here, we set out to resolve the molecular mechanisms behind biofilm matrix assembly of Synechococcus elongatus PCC 7942, a model organism among unicellular cyanobacteria. S. elongatus readily forms biofilms upon disruption of the type IV pili apparatus. Biofilm matrix assembly depends on the functional amyloids EbfG and their secretion machinery (EbfG-T1SS). However, EPS secretion pathways, including that of the EbfGs, and the mechanisms of EbfG aggregation remain speculative. By combining the Applicants’ complementary expertise in microbiology, ‘omics technologies, membrane protein biochemistry and structural biology, we aim to answer the following questions: (i) what are the endogenous inhibitors/stimuli that modulate S. elongatus matrix assembly; (ii) what are the roles and dynamics of tripartite secretion systems during biofilm growth; and (iii) what are the mechanisms of EbfG secretion and maturation, and potential interplay of EbfG-T1SS with other secretion systems. Realization of the collaborative project will offer a comprehensive view on S. elongatus biofilm matrix production at the cellular and molecular levels. We expect the knowledge acquired here will advance our understanding of biofilm formation and will be valuable for applications in green biotechnology.

• DFG Programme: Research Grants