Enhancement of production and activity of alkaline zinc metalloprotease from Salinivibrio proteolyticus using low intensity direct electric current and zinc nanoparticles

Abstract

Objectives: To improve the production and activity of an alkaline zinc metalloprotease from Salinivibrio proteolyticus in response to ZnSO4 (ionic and nanoparticle forms) and low intensity direct electric current (LIDC). Results: A DC of 50 µA for 10 min increased enzyme production from 35 to 53 U ml−1 when applied to the stationary phase bacterial cells. Zn2+ improved enzyme production better than zinc nanoparticles (52 vs. 43.5 U ml−1). Zinc nanoparticles (0.5 mM) added to an enzyme reaction mixture containing casein (0.65 %) and 20 mM Tris/HCl buffer (pH 8) improved enzyme activity more than Zn2+ (42 vs. 36 U ml−1). Conclusion: LIDC exposure (50 µA, 10 min) to the stationary phase bacterial cells increases metalloprotease production in Salinivibrio. A low concentration of zinc nanoparticles (0.5 mM) increases maximum enzyme activity. © 2016, Springer Science+Business Media Dordrecht.