title: Network analysis highlights complex interactions between pathogen, host and commensal microbiota.
abstract: Interactions between bacteria and their host represent a full continuum from pathogenicity to mutualism. From an evolutionary perspective, host-bacteria relationships are no longer considered a two-component system but rather a complex network. In this study, we focused on the relationship between brook charr (Salvelinus fontinalis) and bacterial communities developing on skin mucus. We hypothesized that stressful conditions such as those occurring in aquaculture production induce shifts in the bacterial community of healthy fish, thus allowing pathogens to cause infections. The results showed that fish skin mucus microbiota taxonomical structure is highly specific, its diversity being partly influenced by the surrounding water bacterial community. Two types of taxonomic co-variation patterns emerged across 121 contrasted communities' samples: one encompassing four genera well known for their probiotic properties, the other harboring five genera mostly associated with pathogen species. The homeostasis of fish bacterial community was extensively disturbed by induction of physiological stress in that both: 1) the abundance of probiotic-like bacteria decreased after stress exposure; and 2) pathogenic bacteria increased following stress exposure. This study provides further insights regarding the role of mutualistic bacteria as a primary host protection barrier.
authors.affiliation: Institut de Biologie Intégrative et des Systèmes (IBIS), Département de Biologie, Université Laval, Québec, Québec, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Boutin
authors.affiliation: Institut de Biologie Intégrative et des Systèmes (IBIS), Département de Biologie, Université Laval, Québec, Québec, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Bernatchez
authors.affiliation: Institut des sciences de la mer de Rimouski (ISMER), Université du Québec à Rimouski (UQAR), Rimouski, Québec, Canada.
authors.forename: Céline
authors.initials: C
authors.lastname: Audet
authors.affiliation: Institut de Biologie Intégrative et des Systèmes (IBIS), Département de Biologie, Université Laval, Québec, Québec, Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Derôme
mesh_terms: D000818:Animals; D017756:Aquaculture; D001483:Base Sequence; D016000:Cluster Analysis; D059014:High-Throughput Nucleotide Sequencing / Q000662:veterinary; D054884:Host-Pathogen Interactions / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood; D064307:Microbiota / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009093:Mucus / Q000382:microbiology; D012867:Skin / Q000382:microbiology; D013045:Species Specificity; D013312:Stress, Physiological / Q000502:physiology*; D013559:Symbiosis / Q000502:physiology*; D014337:Trout / Q000382:microbiology* / Q000502:physiology
chemical_list: D006854:Hydrocortisone