2008 Volume 54 Issue 6 Pages 385-392
A novel psychro-tolerant bacterium, Curtobacterium luteum, secreting an extracellular protease was isolated from the soil of Gangotri glacier, Western Himalaya. Maximum enzyme production was achieved when the strain was grown in a pH-neutral medium containing skim milk at 15ºC over 120 h. The metal ions such as Zn2+ and Cr2+ enhanced enzyme production. The specific activity of purified enzyme was 8,090 units/mg after 34.1-fold purification. The 115 kDa enzyme was a metalloprotease (activity inhibited by EDTA and EGTA) and showed maximum activity at 20ºC and pH 7. The enzyme was active over a broad pH range and retained 84% of its original activity between pH 6 and 8. There was no loss in enzyme activity when exposed for 3 h at 4–20ºC. However, the enzyme lost 65% of activity at 30ºC, and was almost inactivated at 50ºC, but was resistant to repeated freezing and thawing. The enzyme activity was stimulated by manganese ions; however, it was inactivated by copper ions.