A large number of Photobacterium phosphoreum (6-7 log/g) was isolated from “tamagoyaki” (a kind of nigirisushi; Japanese food) that had been lumineferous in the dark. The isolates were smeared on the surfaces of sliced “tamagoyakis”. After the incubation at 10°C for 48 hr or at 25°C for 24 hr, the surfaces became luminous. It was indicated that this abnormality of “tamagoyaki” was caused by contamination with and multiplication by P. phosphoreum.
On the surface of “tamagoyaki”, the bacteria in an early growth phase in such a small number as 4 log/g luminesced. Furthermore, the luminescence was observed when pieces of squid, boiled prawn or “yakichikuwa” (a kind of food made of fishes) with the bacteria were incubated, but not observed on pickled Japanese gizzard shad. Nevertheless the the bacteria grew on the surface of tuna, but no luminescence was observed on it.
The bacteria produced a small amount of histamine on squid and tuna (less than 250μg/g), and their ability to putrefy food seemed to be low.
The opitmum concentration of sodium chloride for growth of the bacteria in a medium was 3%, but they grew in food containing sodium chloride less than 0.5%. When sodium chloride in the medium was replaced by potassium chloride, calcium chloride, magnesium chloride, ammonium chloride or sodium phosphate, the bacteria were still able to grow but unable to grow when replaced by potassium phosphate or sucrose. The bacteria metabolized arginine by arginine decarboxylase but not by arginine dehydrolase.