Background : Although tunas represent a significant part of the global fish economy and a major nutritional resource worldwide, their consumption poses a risk of food poisoning through the development of particular bacterial pathogens. However, their microbiome still remains poorly documented. Here, we conducted a multi-compartmental analysis of the taxonomic composition of the bacterial communities inhabiting the gut, skin and liver of two most consumed tropical tuna species (skipjack and yellowfin), from individuals caught in the Atlantic and Indian oceans.
Results : Our results revealed that the composition of the microbiome was independent of fish sex, regardless of the species and ocean considered. Instead, the main determinants were (i) tuna species for the gut and(ii) sampling site for the skin mucus layer, and (iii) a combination of both parameters for the liver. Interestingly, only 4.5% of all ASVs were shared by the three compartments, raising numerous questions about the circulation of microorganisms within the tuna body. Our results also revealed the presence of a unique and diversified bacterial assemblage within the liver, comprising a substantial proportion of histamine-producing bacteria, well known for their potential pathogenicity and their contribution to fish poisoning cases.
Conclusions : These results indicate that the tuna liver is an unexplored microbial niche whose role in the health of both the host and consumers remains to be elucidated.