Author:

Abstract:

Recently, the contribution of the microbiome in host-parasite interactions has received attention as research indicates that this complex community of microorganisms plays a crucial role in host physiology and pathogen resistance (colonization resistance). By consuming common limited resources in competitive microbe-microbe interactions and providing the host of extra food resources, the indigenous gut microbiota is assumed to contribute to limit the attachment, growth and survival of introduced pathogenic bacteria. In our study, we utilized gut microbiota transplants combined with metagenetics to examine the role of the microbiome in host-parasite interactions. Daphnia magna and its parasites is our model system of choice. Firstly, Daphnia individuals (donors) were exposed to one of two different (or no=control) parasite communities (White Fat Cell Disease - Binucleata daphnia community & Pasteuria ramosa - Colligata ordospora -Mitosporidium daphnia community), after which the Daphnia gut was dissected. We assumed that parasite exposure would induce a shift in the gut microbiota in parasite-infected populations and that microbiota beneficial for protection against parasites would be selected. Secondly, Daphnia individuals (recipients) from three clones were made axenic and received the donor microbiome which were pre-exposed to one or no parasite community. We assumed that there was an interaction between the gut microbiome and the host genotype, that mediates the Daphnia tolerance towards infection. Thirdly, we exposed the recipients of each donor microbiome to one or none of the parasite communities. The same parasite communities of the donor exposures were here used to expose the recipients. By doing so, we investigated whether a specific microbiome confers resistance towards a community of particular parasites.