Présentations Colloques

Oral Presentation
8.09
Session 8.09: Hydrogeoecology: a focus on groundwater ecology
Griebler Christian
Diversity and functionality of groundwater viral communities
Viruses are the most abundant and diverse biological entity on the planet and their impact is global. They affect microbial hosts through mortality, re-mineralization of nutrients, and horizontal gene transfer. While viral communities in surface freshwaters and marine systems received considerable attention in the recent past, our knowledge about viruses in groundwater is almost zero. Sampling pristine as well as organically contaminated groundwater from different sites in Germany, we started to shed light into the viral diversity and functionality. Viral communities were concentrated by nanofiltration and then analyzed by means of viral tagging, metagenomic pyrosequencing, and protein cluster (PC) analysis. **Viruses in groundwater were dominated by dsDNA bacteriophages of the families of Myoviridae, Podoviridae and Siphoviridae. The dominance of tailed-morphology Myoviridae in our groundwater sample was confirmed by Transmission Electron Microscopy (TEM). Comparison of the groundwater viral metagenomes with different metagenomes from a variety of other aquatic environments (marine and freshwater) revealed that the freshwater viral consortia were more close to each other than to marine consortia. However, no significant difference between freshwater (including groundwater) and marine viral assemblies could be found, which is likely due to the insufficient sample size of the current database. The cluster richness of each virome, deduced from PCs, was significantly different between the groundwater environments from others, with the highest diversity being observed in groundwater. Mapping metabolic pathways from viral metagenome data obtained from groundwater of an organically polluted site revealed that viruses in this system carry bacterial functional genes related to biodegradation of the site-specific contaminants. Current research is directed to the functional role of viral communities in groundwater ecosystems.
Germany