Screening and characterization of protease from metagenomic library of deep sea sediment

Abstract

Metagenomic cosmid library, containing 7 000 clones with more than 30 kb inserts and covering about 210 Mb metagenomic DNA of uncultured microorganisms from the deep sea sediment of east Pacific, was constructed, and 18 independent clones expressing protease activity were isolated from the library. The analysis of 16S rRNA showed that these proteases originated from Pseudomonas, Stenotrophomonas and Vibrio, respectively. Ten proteases were selected for further study based on the comparison of their activities and 16S rRNA sequence. The results indicated that the optimal pH and temperature for their activities ranged between 7-10 and 10-40 °C, respectively. The Pro20 protease had the lowest optimal temperature at 10 °C. The Prol protease had better potential for exploitation owing to some virtues including high activity at low temperature, better resistant for high pH and temperature.