Four strains with high yield and strong hydrolase activity protease were isolated from the gastrointestinal tract of the Octopus variabilis by transparent circle method.The activity of protease was determined by azocasein method. The protease produced by strain L 2 has the highest hydrolase activity, 4.80U/μg. Besides, the activity of proteases produced by strain L 1 was up to 3.31 U/μg, which was the lowest of the four strains. The molecular weights of proteases produced by strain L 2 were estimated at 105.2, 86.9, 69.3, 37.8 kD by SDS PAGE. Moreover, the optimal reaction temperature and pH of the proteases from strain L 1, L 2 were 40℃ and 8.0. The proteases produced by strain L 3 and L 5 have the highest activity at 50, 60 ℃ and 8.5, 7.0, respectively.
