Identification, Isolation, Cloning, and Expression of a New Alkaline Serine Protease Gene from Native Iranian...

Proteases are one of the most important and widely applicable proteolytic enzymes that are used in various industries. The aim of this study was to identify, isolate, characterize, and clone the new extracellular alkaline protease from the native bacterium Bacillus sp. RAM53 that was isolated from rice fields in Iran. In this study, first, the primary assay of protease production was performed. The bacteria were cultured in a nutrient broth culture medium at 37° C for 48 h, and then, the enzyme extraction was performed. Enzyme activity was measured by standard methods in the range of 20 to 60 °C and the range of pH 6.0 to 12. Degenerate primers were designed to alkaline protease gene sequences. The isolated gene was cloned into the pET28a+ vector, the positive clones were transferred to Escherichia coli BL21, and the expression of the recombinant enzyme was optimized. The results showed that the optimum temperature and pH of the alkaline protease were 40° C and 9.0, respectively, and were stable at 60° C for 3 h. The molecular weight of the recombinant enzyme was 40 kDa in SDS-PAGE. The recombinant alkaline protease was inhibited by the PMSF inhibitor, indicating that the enzyme was serine protease. The results showed that the sequence alignment of the enzyme gene with the other alkaline protease gene sequences related to Bacillus was 94% identity. The result of Blastx showed about 86% identity to the S8 peptidase family in Bacillus cereus and Bacillus thuringiensis and other Bacillus species. The enzyme may be useful for various industries.