Protease Formation by a Marine Psychrophilic Bacterium

Proteolytic activity was found in the culture fluids of numerous psychrophilic bacteria isolated from terrestrial or marine samples. Among these organisms, a marine psychrophilic bacterium, Pseudomonas sp. No. 548, showed the highest proteolytic activity. This organism required salts of sea water for both growth and protease formation. The optimum temperature for the growth of this organism was 20°C. The formation of protease was the greatest at 5°C and decreased with increasing temperature. The extracellular protease system was fractionated into at least two components having proteolytic activities by chromatography with DEAE-cellulose. Increasing culture temperature tended to increase the activity ratio of Fraction I to Fraction II. Some cultural conditions for protease formation were investigated.