A new type of histamine-forming bacteria. Isolation of psychrophilic and halophilic histamine-forming bacteria from Scomber japonicus.

Abstract

The present paper deals with the isolation and identification of a new type of histamine-forming bacteria. The homogenates of common mackerel flesh, stored at 5°Cand 20°C, contained large amounts of histamine. The bacterial isolates from these two homogenates were examined for their ability to produce histamine in mackerel infusion broth. The organisms of one group of the isolates, which could not be identified with any of the known genera, were capable of producing histamine at a temperature of 5°C. All of the group strains were Gram-negative coccobacilli and motile by one polar flagellum; they also fermentatively metabolized glucose to acid and gas. These strains grew at 5°Cbut not at 35°C; they grew well in a medium with 1 to 3 percent NaC1, but did not grow in the absence of NaC1. The authors have named the unidentified organisms “N-group bacteria”. This bacteria group may be important for the problem of food hygience, because it is a new type of histamine-forming becteria.