Host-associated bacterial communities of Hydra are partially robust to invasion from environmental sources

In this study, we investigated the role of environmental sources, particularly water, in shaping the spatial and temporal variation of microbial communities in freshwater Hydra, employing both correlational and experimental methodologies. We collected Hydra polyps along with water samples from multiple sites within 15 Hungarian populations and bacterial community composition was assessed using 16S sequencing. To assess the impact of water microbiota in driving geographical variation in the microbiota composition of Hydra, we conducted correlation analyses between the two communities. Next, using laboratory experiments we cultured field-collected Hydra polyps obtained from three populations either in native water or in water sourced from another location, to observe the temporal effect of source water on the microbiome composition.