The MOME

Although tunas represent a significant part of the global fish economy and a major nutritional resource worldwide, their microbiome 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 tropical tuna species (skipjack and yellowfin). Our results revealed that the composition of the microbiome was independent of fish sex, regardless of the species and sampling site considered. Instead, the main determinants were (i) tuna species for the gut and (ii) sampling site for the skin mucus layer. For the first time, our study revealed the presence of a unique and diversified bacterial assemblage within the liver, comprising a substantial proportion of histamine-producing bacteria. 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.