Expression and purification of soluble porcine cystatin 11 in Pichia pastoris

Cystatin 11 (CST11) belongs to the cystatin type 2 family of cysteine protease inhibitors and exhibits antimicrobial activity in vitro. In this study, we describe the expression and purification of recombinant porcine CST11 in the Pichia pastoris system. We then assess its antimicrobial activity against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis by liquid growth inhibition assay. Kinetic studies indicate that the recombinant porcine CST11 has high potency against E. coli and S. aureus. Scanning electronic microscope analysis showed that CST11 might be targeting the bacterial membrane and, thus, could potentially be developed as a therapeutic agent for inhibiting microbe infection without the risk of antibiotic resistance.