Purification, characterization and antibacterial potential of streptococcus-derived protease: Insights into biomedical applications

Abstract

Proteases are key industrial enzymes with significant biomedical potential. A protease-producing Streptococcus isolate is cultivated in casein–starch medium under optimized conditions (pH 7.4, 37 °C, 36 h). The enzyme is purified by ammonium sulfate precipitation, dialysis, ion exchange, and gel filtration, yielding a 2.74-fold increase in specific activity (13.8 to 37.83 U/mg) with 4.2% final yield. SDS-PAGE confirmed near-homogeneity. The protease showed optimum activity at 40 °C and pH 7.0, with moderate thermostability. Accordingly, the present study aims to isolate and identify a protease-producing Streptococcus strain, purify the extracellular enzyme through a multistep process, and characterize its biochemical properties in terms of activity, stability, and optimal operating conditions. Furthermore, the antibacterial potential of the purified protease is evaluated against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria to assess its efficacy as a natural antimicrobial agent. Through this investigation, the work seeks to establish the Streptococcus-derived protease as a promising candidate for biomedical and therapeutic applications, particularly in the context of enzyme-based antibacterial strategies. Antibacterial assays revealed dose-dependent inhibition of Escherichia coli and Staphylococcus aureus, with stronger activity against Gram-positive bacteria, highlighting its potential as a promising antimicrobial biocatalyst.