Exploring the secondary metabolite driven interactions of Planctomycetes with macroalgae

• Applicants: Professor Dr. Christian Jogler; Dr. Frank Surup
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: from 2016 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 287900682

Planctomycetes are ubiquitous and abundant bacteria that possess unique cell biological traits such as cell division through budding, endocytosis-like uptake of nutrients and cytosolic compartmentalization [1]. While their unusual cell division results in slow growth, they surprisingly dominate biofilms on kelp [2]. Such nutrient rich habitats attract other -faster growing- heterotrophic bacteria that should be able to outcompete Planctomycetes. However, during a pilot study we obtained cultures of three novel planctomycetal genera from kelp and found Planctomycetes being the dominant phylum among the biofilms on many phototrophs. This fits to the observation that Planctomycetes can degrade complex polysaccharides of algal origin [3, 4]. Analyzing available planctomycetal genomes, we demonstrated their potential for secondary metabolite production [3]. Recently we determined antimicrobial activity of these metabolites (Jeske et al. appendix). Thus we hypothesize that Planctomycetes are attracted by kelp through secretion of specific carbohydrates that trigger them to attach to the algal surface and to form biofilms. Kelp might attract Planctomycetes to employ them as biofouling control, using their antimicrobial secondary metabolites to defeat other bacteria or eukaryotes. The isolation of these secondary metabolites from cultures of Planctomycetes by a bioassay-guided fractionation approach will allow elucidating the structures of novel chemical entities by assorted spectroscopic and spectrometric experiments (mainly NMR, HRMS, Xray). By assessing their bioactivity we will be able to estimate their ecological role in nature. Understanding the organismic and chemical background of this putative symbiosis is the main objective of this proposal. Furthermore we aim to isolate novel planctomycetal species with putative biotechnological relevance and to elucidate novel lead structures with biological activity.

• DFG Programme: Research Grants
• International Connection: Netherlands