Population of halophilic bacteria in salted fish products made in the Loochoo Islands, Okinawa and the Noto Peninsula, Ishikawa, Japan

The number of halophilic bacteria in 17 kinds of salted fish products made in the Loochoo Islands, Okinawa (in the subtropical zone) or the Noto Peninsula, Ishikawa (in the temperate zone, facing the Sea of Japan) was examined with media containing 0-20% (w/v) NaCl. In four of five samples of 'suku-garasu', salted fries of Siganus fuscescens made in Okinawa containing 21-28% NaCl, the bacterial number was 10(3) c.f.u./g or lower. For the other 'suku-garasu' that contained 16% NaCl, there were 10(7) c.f.u./g of halophilic lactococci with high levels of lactic acid and water-soluble proteins, free amino acids and volatile basic nitrogen, as indicators of fermentation in protein-rich foods. In salted mackerel made in the Noto Peninsula, the number of halophilic lactococci was 10(5)c.f.u./g, which was higher than that in salted squid. Two salted mackerel samples that contained 22-24% NaCl had a high level of lactic acid. However, the lactic acid concentration was very low in a sample of salted mackerel containing 28% NaCl. Characteristics of the isolated halophilic lactococci were similar with those of genus Tetragenococcus. Effects of NaCl concentration and temperature on the growth of halophilic lactococci were also examined.