title: Exploring the hologenome concept in marine bivalvia: haemolymph microbiota as a pertinent source of probiotics for aquaculture.
abstract: Haemolymph-associated microbiota of marine bivalves was explored for antibacterial activity against important aquaculture pathogens. A collection of 843 strains were cultured from the haemolymph of four bivalve species (Crassostrea gigas, Mytilus edulis, Pecten maximus and Tapes rhomboides) collected by deep-sea diving in the Glenan Archipelago (France). Cell-free culture supernatants were investigated for antibacterial activity using the well-diffusion assay. About 3% of haemolymph-associated cultivable bacteria displayed antibacterial activity toward Gram-negative pathogens. Among the active bacteria, Pseudoalteromonas strains exhibited the highest antibacterial activity. The cell-free culture supernatant of one of them, named hCg-51, was able to inhibit the growth of bacterial pathogens even after drastic dilution (1 : 1024). Hemocyte survival was not significantly altered in the presence of the haemolymph-associated strains assayed. Moreover, a dose-dependent beneficial effect on hemocyte survival rates was observed with the hCg-51 strain. These results suggest that haemolymph microbiota may participate in bivalve protection and therefore confer a health benefit on the host. As a result, the results highlight bivalve haemolymph microbiota as a promising novel source for aquaculture probiotics. This work also gives a first insight into the contribution of the haemolymph-associated microbiota as part of the bivalve 'hologenome'.
authors.affiliation: Université de Brest, EA3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne (LUBEM), IFR148 ScInBioS, Institut Universitaire de Technologie, Quimper, France.
authors.forename: Florie
authors.initials: F
authors.lastname: Desriac
authors.forename: Patrick
authors.initials: P
authors.lastname: Le Chevalier
authors.forename: Benjamin
authors.initials: B
authors.lastname: Brillet
authors.forename: Ivan
authors.initials: I
authors.lastname: Leguerinel
authors.forename: Benoît
authors.initials: B
authors.lastname: Thuillier
authors.forename: Christine
authors.initials: C
authors.lastname: Paillard
authors.forename: Yannick
authors.initials: Y
authors.lastname: Fleury
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D017756:Aquaculture; D049872:Bivalvia / Q000382:microbiology*; D002470:Cell Survival; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D005602:France; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006434:Hemocytes / Q000187:drug effects; D006458:Hemolymph / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D064307:Microbiota; D010802:Phylogeny; D019936:Probiotics / Q000302:isolation & purification*; D031161:Pseudoalteromonas / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S
keywords: Pseudoalteromonas; antibacterial; bivalvia; hemolymph; probiotic