Antimicrobial activity of an aspartic protease from Salpichroa origanifolia fruits

ROCHA, GABRIELA F; GUEVARA, MARÍA GABRIELA; KISE, FRANCISCO; PARISI, MÓNICA G; DÍAZ, MARÍA EUGENIA; ROSSO, ADRIANA M

LETTERS IN APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2018 vol. 67 p. 168 - 174

0266-8254

Plant proteases play a fundamental rol in several processes like growth, development and in response to biotic and abiotic stress. In particular, aspartic proteases are expressed in different plant organs and have antimicrobial activity. Previously, we purified an aspartic protease from Salpichroa origanifolia fruits called salpichroin. The aim of this work was to determine the cytotoxic activity of this enzyme on selected plant and human pathogens. For this purpose, the growth of the selected pathogens was analysed after exposure to different concentrations of salpichroin. The results showed that the enzyme was capable of inhibiting Fusarium solani and Staphylococcus aureus in a dose-dependent manner. It was determined that 1.2 µM of salpichroin was necessary to inhibit 50% of conidial germination, and the minimal bactericidal concentration was between 1.9- 2.5 µM. Using SYTOX Green dye we were able to demonstrate that salpichroin cause membrane permeabilization. Moreover, the enzyme treated with its specific inhibitor pepstatin A did not lose its antibacterial activity. This finding demonstrates that the cytotoxic activity of salpichroin is due to the alteration of the cell plasma membrane barrier but not due to its proteolytic activity. Antimicrobial activity of the aspartic protease could represent a potential alternative for the control of pathogens that affect humans or crops of economic interest.