engleski

Dominant culturable microbiota associated with farmed Atlantic bluefin tuna (Thunnus thynnus) in the Adriatic Sea

Atlantic bluefin tuna (Thunnus thynnus) is a high- value product and Croatia is one of the primary Mediterranean producers. The study aimed to examine the microbial community naturally associated with adult Atlantic bluefin tuna in the Adriatic, as a continuation of our earlier work. Microbiological analysis was conducted at commercial tuna farm in the Middle Adriatic. Samples of the swabs from the gills and skin were diluted in sterile PBS. Dilutions of swab samples were then plated onto non-selective TSA supplemented with 1% NaCl, and plates were incubated at 22 °C. To determine Vibrio count, samples were inoculated onto selective TCBS Agar and incubated at 35 °C. The isolates were characterised phenotypically using the API kits (bioMerieux, France): API 20 NE, API 20 E, API Staph, API Coryne and API 50 CHL. API results were interpreted with the aid of the APIWEB platform. The bacterial community associated with tuna in our study comprised at least 6 genera, most of which were Gram-negative. The dominant bacteria were Pasteurella and Moraxella, whereas Staphylococcus was the dominant Gram-positive genera. The proportion of isolates that was Gram- positive in our study was significantly higher on the skin (49.0%) than on the gills (6.6%). We characterised bacteria that are naturally associated with healthy farmed Atlantic bluefin tuna. These results will provide a valuable baseline reference for future studies of how farming conditions affect the health of farmed tuna, risk of food spoilage and the safety of raw and processed tuna as food for humans.

Atlantic bluefin tuna ; Thunnus thynnus ; microbial community ; aquaculture ; food safety

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