Planctomycetes as a source of novel secondary metabolites: triggers and regulation of their biosynthesis and engineered production in native strains or heterologous hosts

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Planctomycetes represent a phylum of environmentally important bacteria often associated with phototrophs such as macro- and microalgae and thus play a key role in global carbon and nitrogen cycles. Several planctomycetal species grow slowly with doubling times of up to one month. Most other heterotrophs occupying same ecological niches divide much faster but fail to outcompete Planctomycetes. It is assumed that the high abundance of Planctomycetes in marine environments results from the synthesis of secondary metabolites, which might act as potent antimicrobials or algicidals. This notion is further supported by the complex life cycle of Planctomycetes and quite large genomes for prokaryotes, characteristics that are typical of bacteria known for their bioactive potential. The proposed project aims at a detailed characterization of the secondary metabolome of planctomycetal species. Beyond the identification of novel planctomycetal secondary metabolites, in particular the underlying biosynthetic pathways and the regulation of their production (e.g. as response to environmental triggers) will be analyzed in more detail. Biosynthetic pathways for interesting secondary metabolites will subsequently be reconstructed by functional expression of planctomycetal genes in genetically manipulable microbial host organisms (including already genetically accessible Planctomycetes). This strategy can provide access to individual compounds in amounts required for a detailed analysis of presumed effects.