Prevalence, isolation and identification of histamine forming bacteria in selected stages of supply chain of Yellowfin tuna export industry in Sri Lanka

This study aimed to identify histamine-forming bacteria (HFB) and the sources of introduction such recommend control measures mitigate histamine formation in yellowfin tuna (YFT). Field samples were collected from multi-day boats that landed at Dikkowita, Negombo, Trincomalee Dondra fishery harbours. Ice fish holds (n=63) chill transport vehicles (n=63), swabs boat decks skin YFT collected. Fish loin (n=15), ice (n=36) (n=18), floor (n=18) processing plants. Presumptive HFB isolated Nivens medium Violet Red Bile Glucose (VRBG) agar screened for forming ability Tripticase soy broth (TSB) supplemented with 1.0% L-histidine. isolates characterized by sequencing approximately 1400 bp 16S rDNA. Seven produced range 3000–4000 ppm TSB samples, a swab sample deck, confirmed as Klebsiella aerogens (n=6) Morganella morganii (n=1) respectively. Hafnia alvei (n=1), Serratia sp. (n=2), Citrobacter freundii Rahnella Aeromonas salmonicida (n=8) also among bacteria. Pseudomonas (n=24) Shewanella baltica (n=7), which are known spoilage showed weak formation. Hence, it is evident histamineforming could be introduced into contacting surfaces. necessitates practice rigorous cleaning procedures adaptation proper postharvest handling minimize contamination fish.