| Intensive screening of microbial isolates for more than 50 years has resulted in commercialization of numerous enzymes with potential applications. However, readily cultured microorganisms represent only 0.1 % to 1 % of the organisms in most habitats. Metagenome, which represents the genomes of total microbiota found in nature, offers a way in directly accessing the genomic DNA of the uncultured microbes. Two sets of metagenomic library was constructed by the used of plasmid pZerO-2 as cloning vector and Escherichia coli TOP10 as host cell. Inserted DNA fragments were varied from 0.7 kb to more than 6 kb. The transformation efficiency of the two libraries ranged from 105 to 106 CFU/ µg DNA. One positive candidate for protease was obtained from 386,816 clones. The clone might encodes for a novel protease since the translated DNA sequence had no similarity with any known protease in the database. |