Cell Membrane Integrity of Candida Albicans after Different Protocols of Microwave Irradiation

Abstract

Pur pose: To evaluate the ability of low time microwaveexposureto inactivate and damage cell membrane integrity of C. albicans. Materials and Methods: Two 200ml C. albicans suspensions were obtained. Sterile dentures were placed in a beaker containing Experimental (ES) or Control suspensions (CS). ES was microwaved at 650 W for 1, 2, 3, 4 or 5 min. Suspensions were optically counted using Methylene blue dye as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca ++ (Cresolphthalein Complexone method); DNA (spectrophotometer measurements at 260nm) and K + (selective electrode technique). Data were analyzed by Student-t test and linear regression (α=0.05). In addition, flowcytometry analysis of Candida cells in suspensionwas performed using propidium iodide. Results: All ES cells demonstrated cell membrane damage at 3, 4 and 5 min,viable cells were nonexistent at 3, 4 and 5 min ES ASD plates and optical density of ES and CS was not significantly differentfor all exposition times. ES cells released highcontents of protein, K + , Ca ++ and DNA after 2 min exposition when compared to that of the CSs. Similar results were observed with flo w cytometry analysiswith regard to the periodsof microwave exposure. Conclusions: Microwave irradiation inactivated C. albicansafter 3min and damaged cell membrane integrity after 2 min exposition.