Histamine production by two Enterobacteriaceae strains isolated from tuna (Thunnus thynnus) and jack mackerel (Trachurus murphyii)

Abstract

Growth of Enterobacteriaceae in scombroids such as tuna (Thunnus thynnus) and jack mackerel (Trachurus murphyii) usually promotes aminoacid decarboxylation to biogenic amines. Among these compounds, histamine, produced by histidin-decarboxylase activity, is reported as toxic. The objective of this study was to compare histamine production by a strain, identified as Serratia liquefaciens, isolated from tuna (T. thynnus) caught in the Gulf of Mexico and Morganella morganii isolated from Chilean jack mackerel (T. murphyii). Morganella morganii had higher histamine producing ability in a synthetic medium than S. liquefaciens, presumably as a result of stressing conditions on M. morganii. However, in a medium formulated with muscle protein extracts obtained from tuna S. liquefaciens showed higher histamine production at similar microbial counts. In this medium, histidine was extracted together with proteins from tuna striated muscle, it was assumed that it acted as histamine production promoter.