Tracking spoilage bacteria in the tuna microbiome

Abstract

Like other seafood products, tuna is highly perishable and sensitive to microbial spoilage. Its consumption, whether fresh or canned, can lead to severe food poisoning due to the activity of specific microorganisms, including histamine-producing bacteria. Yet many grey areas persist regarding their ecology, conditions of emergence and proliferation in fish. In this study, we used 16S rDNA barcoding to investigate post-mortem changes in the bacteriome of fresh and brine-frozen yellowfin tuna (Thunnus albacares), until late stages of decomposition (i.e. 120 h). The results revealed that despite standard refrigeration storage conditions (i.e. 4°C), a diverse and complex spoilage bacteriome developed in the gut and liver. The relative abundance of spoilage bacterial taxa increased rapidly in both organs, representing 82% of the bacterial communities in fresh yellowfin tuna, and less than 30% in brine-frozen tuna. Photobacterium was identified as one of the dominant bacterial genera, and its temporal dynamics were positively correlated with histamine concentration in both gut and liver samples, which ultimately exceeded the recommended sanitary threshold of 50 ppm in edible parts of tuna. The results from this study show that the sanitary risks associated with the consumption of this widely eaten fish are strongly influenced by post-capture storage conditions.

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

“…The osmotolerant Psychrobacter spp., identified as a core genus in the seabream in our study, was also found by Quero and collaborators (2023) and assigned to the core members in sea-farmed seabream in the Mediterranean area [ 23 ].In Piredda and collaborators (2023), Psychrobacter was described as one of the most representative taxa of Scomber scombrus from FAO areas 27.4, 27.7 and 27.8. Furthermore, Psychrobacter was identified as SSOs in the evaluation of tuna spoilage, highlighting its possible role as a spoilage marker [ 28 ]. Taxa such as Carnobacterium and Pseudomonas, identified in our dataset can be considered as SSOs for the assessment of fish freshness, moreover abundances of Escherichia-Shigella and Staphylococcus can be monitored to ensure the fish healthiness.…”

Improving the microbiological safety and quality of aquatic products using nonthermal processing

“…This change resulted in an increase in volatile substances, such as low‐grade aldehydes, alcohols, and ketones, in the fish, causing serious fatty acid oxidation and intensifying the fishy smell. The strong spoilage capacity of Pseudomonas was also demonstrated in tuna (Thunnus albacares) (Gadoin et al., 2022). Other important spoilage bacteria include Psychrobacter , Acinetobacter , Aeromonas , Carnobacterium , and Brochothrix thermosphacta (Huang et al., 2021, 2022; Zhang et al., 2022).…”