Abstract
Production conditions and some properties of the extracellular protease produced by Cytophaga columnaris isolated from a diseased Japanese eel Anguilla japonica were examined. The enzyme production was stimulated by the addition of pepton (Kyokuto) and sodium acetate. Divalent metal ions such as Mg2+, Ca2+, and Mn2+ were also required, and the addition of yeast extract at the restricted concentration increased the enzyme production. Optimum pH range of incubation for the enzyme production was between 6.8 and 7.0, and the optimum temperature of incubation was around 25°C. The enzyme production occurred with the growth of the organism, and the enzyme was accumulated during the stationary phase of growth in a liquid medium under aerobic conditions. The proteolytic activity in the culture supernatant was inactivated at 60°C for 60min, and the activity was reduced to 78% at 40°C for 60min. The activity was stable in the range of pH 7.5 to 8.5, and maximum activity was occurred at pH 8.0.
