THE POTENTIAL IMPACT OF LYTIC VIRUSES ON THE TAXONOMIC RESOLUTION OF BACTERIOPLANKTON IN PRODUCTIVE FRESHWATER RESERVOIRS

Man-made reservoirs that receive significant inputs of terrestrial organic matter exhibit distinct and diverse bacterial communities. In this study, we used Illumina MiSeq sequencing to assess the bacterial community structure in two productive freshwater reservoirs, Villerest and Grangent, located in Central France. Our analysis revealed that the bacterial communities in both reservoirs varied spatially and temporally. Villerest reservoir was found to harbor more diverse bacterial communities compared to Grangent reservoir. The dominant bacterial groups in both reservoirs were the hgcI clade (Actinobacteria) and Limnohabitans (Betaproteobacteria), which are known to have adaptive strategies related to resource utilization and top-down control. In Villerest reservoir, the occurrence of temporary anoxia due to thermal stratification, especially during summer, promoted the presence of anoxygenic phototrophic and methanotrophic bacteria. Interestingly, we observed a low bacterial richness, which we attributed to viral lysis. This suggests that a small number of highly active bacterial populations sustain high bacterial activity and viral abundances in these reservoirs. Weighted UniFrac analysis indicated that a minimum threshold of 10% viral infection and a virus-to-bacteria ratio of 10 were needed to significantly impact the phylogenetic structure of the bacterial community. Thus, depending on the levels of viral infection, viruses may play a dominant role in shaping and structuring bacterial communities in these man-made freshwater systems, surpassing other top-down factors.

Primary Presenter: Telesphore Sime-Ngando, CNRS, Centre National de la Recherche Scientifique (telesphore.sime-ngando@ird.fr)

Authors:

Telesphore Sime-Ngando, Laboratoire Microorganismes: Génome et Environnement  (telesphore.sime-ngando@uca.fr)

J. Keshri, MedGenome Labs Limited  (research@medgenome.com)

A.S. Pradeep Ram, Laboratoire Microorganismes: Génome et Environnement  (Pradeep_Ram.ANGIA_SRIRAM@uca.fr)