Enhancing seafood traceability: tracking the origin of seabass and seabream from the tuscan coast area by the analysis of the gill bacterial communities.

Abstract

Background: The seafood consumption and trade have increased over the years, and along its expected expansion pose major challenges to the seafood industry and government institutions. In particular, the global trade in fish products and the consequent consumption are linked to reliable authentication, necessary to guarantee lawful trade and healthy consumption. Alterations or errors in this process can lead to commercial fraud and/or health threats. Consequently, the development of new investigative tools became crucial in ensuring unwanted scenarios. Here we used NGS techniques through targeted metagenomics approach on the V3-V4 region of the 16S rRNA genes to characterize the gill bacterial communities in wild-caught seabream (Sparus aurata) and seabass (Dicentrarchus labrax) within different fisheries areas of the "Costa degli Etruschi'' area in the Tuscan coast. Our challenge involved the possibility of discriminating between the microbiota of both fish species collected from three different fishing sites very close to each other (all within 100 km) in important areas from a commercial and tourist point of view.

Results: Our results showed a significant difference in the assembly of gill bacterial communities in terms of diversity (alpha and beta diversity) of both seabass and seabream in accordance with the three fishing areas. These differences were represented by a unique site -related bacterial signature, more evident in seabream compared to the seabass. Accordingly, the core membership of seabream specimens within the three different sites was minimal compared to the seabass which showed a greater number of sequence variants shared among the different fishing sites. Therefore, the LRT analysis highlighted the possibility of obtaining specific fish bacterial signatures associated with each site; it is noteworthy that specific taxa showed a unique association with the fishing site regardless of the fish species. This study demonstrates the effectiveness of target-metagenomic sequencing of gills in discriminating bacterial signatures of specimens collected from fishing areas located at a limited distance to each other.

Conclusions: This study provides new information relating the structure of the gill microbiota of seabass and seabream in a fishing area with a crucial commercial and tourist interest, namely "Costa degli Etruschi". This study demonstrated that microbiome-based approaches can represent an important tool for validating the seafood origins with a central applicative perspective in the seafood traceability system.