PSYCHROTROPHILIC ALKALINE PROTEASE FROM A DEEP SEA PSYCHROTROPHILIC Strain Pseudomonas sp. SM9913

More than 200 psychrotrophilic strains excreting protease were isolated from 1 855 meter deep sea silt and were puri-fied. 3 strains of them excreted psychrotrophilic protease. The psychrotrophilic characteristics of the protease excreted by one of the three strains——Pseudomonas sp. SM9913(P.SM9913)were preliminarily studied. Strain P. SM9913 could grow at 0 ℃. The optimum temperature for growth was about 15 ℃. And the highest temperature for growth was 35 ℃, which suggested that stain P. SM9913 was psychrotrophilic. The highest specific synthetic rate of the protease occurred at about 10 ℃. The optimum temperature of the protease for casin catalysis was 35 ℃, and the highest protease activity for casin catalysis was at pH8.0. The protease was susceptible to heat treatment, and the half time for the decrease of protease activity was 6 minutes when incubated at 40 ℃. These results showed that this protease was psychrotrophilic. The activity of the protease was inhibited by EDTA, indicating that this protease belonged to metalprotease.