| Abstract: | 107 strains producing protease were screened from 260 strains of Ant- arctic psychrophilic bacteria,among which proteolytic activity of five strains was more than 45 U ml~(-1).The 16S rRNA gene sequences homology and phylogenet- ic analysis of five Antarctic psychrophilic bacteria showed that NJ276、NJ5-9、 NJ16-70、NJ345 belonged to the described genus Pseudoalteromonas and NJ341 belonged to the genus Colwellia.The growth and the protease characteristic of four Antarctic psychrophilic bacteria had been studied,and the result showed that the optimal temperature for growth and protease-producing of four strains was about 10℃.Their growth and protease-producing were still high during in- cubating 2-5 days.The maximum proteolytic activity occurred at pH 9 for four Antarctic psychrophilic bacteria.The optimal temperature of protease action of both strains NJ276 and NJ5-9 was about 50℃,however,the optimal temperature of protease action of both strains NJ341 and NJ345 was about 40℃,and their proteolytic activity under 0℃ exhibited nearly 30% of the maximum activity, but their thermal stabilities were weaker.These results indicated that proteases from NJ341 and NJ345 were low-temperature proteases. |
