Prevalence and Histamine Productivity of Histamine-Producing Bacteria in Processed Seafood Products

Abstract

The prevalence of histamine-producing bacteria was examined in 100 commercially available processed seafood products and the histamine productivity of the isolated bacteria was evaluated. Aerobic plate count of the processed seafood samples ranged from below the detection limit to 10⁸ CFU/g and mostly ranged between 10³ to 10⁵ CFU/g. Histamine-producing bacteria were detected in 44 out of the 100 samples: 24 out of the 50 dried products and 20 out of the 50 pickled products. The contamination level of histamine-producing bacteria was generally low (<10² MPN/100 g), although a wide range of processed seafood products might be contaminated. Of the 163 histamine-producing bacterial isolates, 124 were identified as Raoultella ornithinolytica, 25 were as Morganella morganii, and 6 were as Enterobacter aerogenes. R. ornithinolytica/planticola isolated in this study showed high histamine-productivity almost comparable to the notable histamine-producer M. morganii. Our findings indicate that R. ornithinolytica/planticola might be as important histamine-producing bacteria as M. morganii in Enterobacteriaceae.