Isolation of ice-nucleating active bacterium from mackerel [Scomber australasicus] and its properties

"An ice-nucleating bacterium, designated MACK-4, was isolated from ice-stored mackerel (Scomber australasicus) and identified as a Pseudomonas fluorescens. The optimal temperature and pH for its growth in nutrient broth with 2.5% glycerol (NB-G) were 15 deg C and 6.5, respectively.The maximal ice-nucleating activity (INA) was obtained after 54 h incubation at 15 deg C. However, the INA was almost completely lost after 48 h incubation at 25 deg C or higher. The growth and INA decreased with increase of NaCI added in NB-G within 0.0-4.0%. The INA of MACK-4 was very stable at 5-25 deg C,pH 4.0-9.5, while that of isolated ice-nucleating matter from MACK-4 was stable at 5-25 deg C, pH 5.5-9.0."