Histamine-producing bacteria in decomposing skipjack tuna (Katsuwonus pelamis)

Area of Science:

• Food Microbiology
• Marine Biology
• Biochemistry

Background:

• Skipjack tuna spoilage is a significant concern for food safety and economic losses.
• Histamine formation by bacteria is a primary indicator of fish spoilage.
• High temperatures accelerate bacterial growth and histamine production in fish.

Purpose of the Study:

• To investigate bacterial spoilage and histamine formation in skipjack tuna under controlled conditions.
• To identify bacterial species responsible for histamine production in decomposing tuna.
• To assess the histidine decarboxylase activity of isolated bacteria.

Main Methods:

• Incubation of whole skipjack tuna in seawater at 38°C.
• Isolation and identification of bacterial strains from tuna loin tissue.
• Culturing isolates in histidine-containing media to detect histamine production.
• Measurement of histidine decarboxylase activity using tuna broth and buffered histidine solutions.

Main Results:

• Over 92% of 134 bacterial isolates were facultative or obligate anaerobes.
• Eighteen isolates demonstrated histamine production.
• Identified histamine-producing bacteria include Clostridium perfringens, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus mirabilis, and Vibrio alginolyticus.
• Histidine decarboxylase activity was confirmed in several isolates.

Conclusions:

• Anaerobic bacteria play a key role in histamine formation during skipjack tuna spoilage.
• Specific bacterial species, including C. perfringens and V. alginolyticus, are significant contributors to histamine accumulation.
• Understanding these bacterial dynamics is vital for developing effective strategies to prevent tuna spoilage and ensure food safety.