Seaweeds influence oyster microbiota and disease susceptibility

Abstract

A growing awareness of role that microbiota can play in mediating the effects of pathogens on hosts has given rise to the concept of the pathobiome. Recently, we demonstrated that the Pacific oyster mortality syndrome affecting Crassostrea gigas oysters is caused by infection with the Ostreid herpesvirus type 1 (OsHV‐1) followed by infection with multiple bacterial taxa. Here we extend the concept of this pathobiome beyond the host species and its bacterial microbiota by investigating how seaweed living in association with oysters influences their response to the disease. We hypothesized that by their mere presence in the environment, different species of seaweeds can positively or negatively influence the risk of disease in oysters by shaping their bacterial microbiota and their immune response. Although seaweed and oysters do not have direct ecological interactions, they are connected by seawater and likely share microbes. To test our hypothesis, oysters were acclimated with green, brown or red algae for 2 weeks and then challenged with OsHV‐1. We monitored host survival and pathogen proliferation and performed bacterial microbiota and transcriptome analyses. We found that seaweeds can alter the bacterial microbiota of the host and its response to the disease. More particularly, green algae belonging to the genus Ulva spp. induced bacterial microbiota dysbiosis in oyster and modification of its transcriptional immune response leading to increased susceptibility to the disease. This work provides a better understanding of a marine disease and highlights the importance of considering both macrobiotic and microbiotic interactions for conservation, management and exploitation of marine ecosystems and resources.

Cross-talk and mutual shaping between the immune system and the microbiota during an oyster's life

“…Bacterial taxa Colwelliaceae, Cyanobacteria and Rhodobacteraceae are indeed significantly associated with oyster families harbouring higher resistance to POMS [ 15 ]. Beyond members of the oyster microbiota, cohabitation of oysters with macroalgae mitigates their resistance to POMS by modifying microbiota composition and affecting transcriptional response to OsHV-1 infection [ 127 ]. We argue that modulating oyster physiology and immune system through microbial exposure is a promising way to increase resistance to pathogens.…”

Antimicrobial Resistance Profile of Planctomycetota Isolated from Oyster Shell Biofilm: Ecological Relevance within the One Health Concept

“…The family Pirellulaceae includes the well-reported genus Rhodopirellula, which comprises the majority of the isolated strains within this family [41]. Bacteria belonging to this genus have been detected in the soft tissues of oysters using molecular methods [26,42]. In the present study, 95% of the isolates were identified as R. baltica, which is in accordance with the well-known cosmopolitan distribution of this species, already found in macroalgae, mussel shell biofilm, marine sediments and also in the water column [8,31,43,44].…”