More than a gut feeling? The composition, diversity and variability of the planarian microbiome

Abstract

Many animals live in close association with complex microbial communities. The so-called microbiome includes bacteria, fungi and viruses, which often contribute to the hosts physiology and health. Recently a functional link between endogenous bacteria, planarian physiology and the regeneration process was described. Disturbances of the microbiome resulted in tissue lesions and degeneration, although the exact function of the associated bacteria for planarian physiology remains unknown. Therefore, in this study, we investigated the planarian microbiome more in detail to gain insight into the composition, diversity and variability. We found that bacteria were present at the epidermis and in the gut of Schmidtea mediterranea. Via 16S rRNA sequencing, we showed an overall abundance of Betaproteobacteriales in diverse conditions, although at lower taxonomic levels variation between individuals and conditions was observed. The microbiome was sensitive to external stressors, especially after exposure to silver nanoparticles. Finally, our results also suggested fluctuations in the planarian microbiomes during the different phases of the regeneration process. Together, these findings form a solid basis to understand the nature and variability of microorganism associations to further elucidate their role in planarian physiology.