Nancy Weiland-Bräuer

Marine eukaryotes offer diverse surfaces for attachment and colonization, e. g. mucosa-covered epithelia. Bacteria occurring in the marine environment possess the abilities to colonize these surfaces via biofilm formation or even invasion. Aurelia aurita is an interesting model organism due to its evolutionary age, simple anatomy and existence of different life stages. However, despite a few more general studies, currently no reports on A. aurita associated microbiota or on the holobiont itself are available. A central goal of the proposed project is to compare the role of environment, external disturbance and pathogen challenge for the specificity and functioning of associated microbiota of A. aurita. The associated microbiota of A. aurita will be analyzed by 16S rRNA gene amplicon sequencing comparing different life stages, tissues, lineages and culture conditions. Based on these analyses, the relative effects of the environment and of the host genotype on the establishment and the composition of the respective microbiota will be elucidated. A second major goal addresses whether or not the associated microbiota are involved in host pathogen defense including the mechanisms of signal exchange between host and microbiota and respective interference strategies (quorum quenching). Third, the role of the microbiota for host fitness including life cycle decisions will be analyzed and evaluated to answer questions such as whether high microbial diversity confers a fitness advantage and/or buffers negative effects of environmental stress. Overall the proposed project will allow gaining insight into general and specific hostmicrobe interactions and function of the associated microbiota, as well as evaluating potential coevolution.