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Project A07

Principal Investigators: Prof. Dr. Christian Jogler, Dr. Muriel van Teeseling

Planctomycetal Chemical Mediators Shaping Aquatic Phototrophic Communities

Aquatic phototrophic communities are responsible for most of the global oxygen production and nearly half of the global carbon fixation. Strains belonging to the bacterial phylum Planctomycetota are ubiquitous members of such aquatic phototroph-associated communities. There, they form biofilms in which their abundance can reach up to 80%. This is surprising as they grow much slower than bacteria present in the same habitat, such as Roseobacters. We hypothesize that planctomycetes claim their niche in phototrophic communities by producing chemical mediators. Indeed, we found multiple gene clusters potentially related to secondary metabolite biosynthesis in all planctomycetal genomes analyzed so far. We currently investigate the effects of one such chemical mediator, stieleriacine, that increases the growth of its producer and alters the biofilm-forming ability of two Roseobacter species. Interestingly, stieleriacine increases the biofilm-forming ability of one of them, a producer of the antibiotic tropodithietic acid (TDA) that is detrimental to many bacteria but harmless to the planctomycetes. These findings suggest that chemically mediated multipartite interactions shape bacteria-phototroph communities.

Overview of the proof-of-principle Planctomycete-Roseobacter model system

Despite these advances, many open questions remain. Thus, we would like to deepen our understanding on the role of stieleriacines in community formation and test if they act as quorum sensing molecules. To address this, we use (microfluidic) time-lapse microscopy to study the spatiotemporal organization of biofilms made up of planctomycetes and Roseobacters in the presence and absence of stieleriacines. We will also specifically look at the morphology of Roseobacters as morphology can have an important impact on biofilm formation. Using the technology present in the CRC, we will also be able to follow the spatiotemporal distribution of stieleriacines in these communities. We will then introduce phototrophs that act as a substrate for biofilms into this community, to mimic the natural habitat and investigate how planctomycetal chemical mediators affect the host and competing Roseobacters. In addition, we will investigate planctomycetal chemical mediators present in other aquatic Planctomycete-phototroph communities. Therefore, we perform community analyses in two relevant habitats. Based on these analyses, environmentally relevant synthetic co-cultures of planctomycetes and Roseobacters with macroalgae, microalgae and cyanobacteria will be reconstructed. This allows us to study their mutual effect on growth and morphology of the other partner. Using this approach, we aim to uncover additional (planctomycetal) chemical mediators, for which production is triggered by different interaction partners. These interactions can be visualized on cellular and chemical mediator basis. The project relies on intense interactions with multiple CRC projects and their expertise such as chemical synthesis, structure elucidation of chemical mediators and transcriptomic analyses.

Team A07

Prof. Dr. Christian Jogler

 

 

Institute of Microbiology

 

Friedrich Schiller University Jena

 

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Dr. Muriel van Teeseling

 

Institute of Microbiology

 

Friedrich Schiller University Jena

 

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Dr. Nicolai Kallscheuer

 

Institute of Microbiology

 

Friedrich Schiller University Jena

 

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Myriel Staack

 

Institute of Microbiology

 

Friedrich Schiller University Jena

 

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