Environmental vibrio phage-bacteria interaction networks reflect the genetic structure of host populations

Les réseaux d'interaction vibrio phage-bactérie de l'environnement reflètent la structure génétique des populations hôtes

Karine Cahier (1, 2) , Damien Piel (1) , Rubén Barcia-Cruz (3, 2) , David Goudenège (1, 2) , K Mathias Wegner (4) , Marc Monot (5) , Jesús L Romalde (3) , Frédérique Le Roux (1, 2)

1 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer
2 LBI2M - Laboratoire de Biologie Intégrative des Modèles Marins
3 USC - Universidade de Santiago de Compostela [Spain]
4 AWI - Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine
5 Biomics (plateforme technologique)

Phages depend on their bacterial host to replicate. The habitat, density and genetic diversity of host populations are therefore key factors in phage ecology, but our ability to explore their biology depends on the isolation of a diverse and representative collection of phages from different sources. Here, we compared two populations of marine bacterial hosts and their phages collected during a time series sampling program in an oyster farm. The population of Vibrio crassostreae, a species associated specifically to oysters, was genetically structured into clades of near clonal strains, leading to the isolation of closely related phages forming large modules in phage-bacterial infection networks. For Vibrio chagasii, which blooms in the water column, a lower number of closely related hosts and a higher diversity of isolated phages resulted in small modules in the phage-bacterial infection network. Over time, phage load was correlated with V. chagasii abundance, indicating a role of host blooms in driving phage abundance. Genetic experiments further demonstrated that these phage blooms can generate epigenetic and genetic variability that can counteract host defense systems. These results highlight the importance of considering both the environmental dynamics as well as the genetic structure of the host when interpreting phage-bacteria networks.

Mots clés: vibrio; oyster farm; coevolution; genome; genetic

Domaines: Sciences du Vivant [q-bio]; Génétique; Microbiologie et Parasitologie

Karine Cahier, Damien Piel, Rubén Barcia-Cruz, David Goudenège, K Mathias Wegner, et al.. Environmental vibrio phage-bacteria interaction networks reflect the genetic structure of host populations. Environmental Microbiology, 2023, ⟨10.1111/1462-2920.16366⟩. ⟨hal-04061137⟩