Characterization of Histamine-Producing Bacteria Isolated During Processing of Indonesian Salted-Boiled Longtail (Thunnus sp.) and Eastern Little Tuna (Euthynnus sp.)

Histamine-producing bacteria (HPB) were isolated from Longtail and Eastern Little tuna harvested from Indonesian waters and processed as salted-boiled fish (SBF). Mesophilic and psychrophilic bacteria were isolated on Niven’s agar, screened for histidine decarboxylase activity and the presence of the hdc gene, and then histamine production was quantified. Six genera of HPB were identified: Enterobacter, Erwinia, Hafnia, Klebsiella, Serratia and Shigella. At stationary growth phase , mesophilic isolates produced approximately 400 times more histamine than psychrotrophic isolates. The proportion of hdc-positive isolates increased with SBF processing steps, indicating the importance of food safety measuresto minimize HPB growth and histamine production.