Tracking spoilage bacteria in the tuna microbiome

Area of Science:

• Microbiology
• Food Science
• Marine Biology

Background:

• Tuna is highly perishable, posing food poisoning risks from histamine-producing bacteria.
• The ecology and proliferation of these bacteria in fish remain poorly understood.
• Understanding microbial spoilage is crucial for seafood safety.

Purpose of the Study:

• To investigate postmortem bacteriome changes in fresh and brine-frozen yellowfin tuna.
• To assess the impact of storage conditions on bacterial communities and histamine levels.
• To identify dominant bacterial genera associated with tuna spoilage.

Main Methods:

• 16S rRNA barcoding was used to analyze bacterial communities.
• Samples were collected from fresh and brine-frozen yellowfin tuna up to 120 hours postmortem.
• Histamine concentrations were measured in gut and liver tissues.

Main Results:

• A diverse spoilage bacteriome developed in fresh tuna gut and liver under refrigeration (4°C).
• Spoilage bacteria dominated fresh tuna (82%) but were limited in brine-frozen tuna (<30%).
• Photobacterium abundance correlated positively with histamine levels, exceeding safety thresholds.

Conclusions:

• Post-capture storage conditions critically influence sanitary risks of tuna consumption.
• Brine-freezing effectively controls bacterial growth and histamine formation compared to refrigeration.
• Refrigeration alone is insufficient to prevent significant microbial spoilage in tuna.