title: Candida albicans inactivation and cell membrane integrity damage by microwave irradiation.
abstract: In indicating the microwave irradiation for disinfecting dentures it is necessary to see how this procedure influences Candida albicans integrity and viability. The aim of this study was to evaluate the ability of microwaves to inactivate C. albicans and damage cell membrane integrity. Two 200-ml C. albicans (ATCC 10231) suspensions were obtained. A sterile denture was placed in a beaker containing the Experimental (ES) or the Control suspension (CS). ES was microwaved at 650 W for 6 min. Suspensions were optically counted using methylene blue dye uptake as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550 nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolftaleine complexone method); DNA (spectrophotometer measurements at 260 nm) and K+ (selective electrode technique). Data were analysed by Student's t- or Wilcoxon z-tests (alpha = 0.05). All ES cells demonstrated cell membrane damage. Viable cells were non-existent in the ES ASD plates. No significant difference in optical density between ES and CS was observed (P=0.272). ES cells released significantly high protein (P<0.001, Bradford; P=0.005, Pyrogallol red), K+ (P<0.001), Ca++ (P=0.012) and DNA (P=0.046) contents. Microwaves inactivated C. albicans and damaged cell membrane integrity.
authors.affiliation: Department of Dentistry, Ponta Grossa State University, Paraná, Brazil.
authors.forename: Nara Hellen
authors.initials: NH
authors.lastname: Campanha
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Pavarina
authors.forename: Iguatemy Lourenço
authors.initials: IL
authors.lastname: Brunetti
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Vergani
authors.forename: Ana Lucia
authors.initials: AL
authors.lastname: Machado
authors.forename: Denise Madalena Palomari
authors.initials: DM
authors.lastname: Spolidorio
mesh_terms: D002118:Calcium / Q000032:analysis; D002176:Candida albicans / Q000737:chemistry / Q000502:physiology / Q000528:radiation effects*; D002462:Cell Membrane / Q000528:radiation effects*; D015169:Colony Count, Microbial; D004271:DNA, Fungal / Q000032:analysis; D005656:Fungal Proteins / Q000032:analysis; D008751:Methylene Blue / Q000378:metabolism; D050296:Microbial Viability / Q000528:radiation effects*; D008872:Microwaves; D010539:Permeability; D011188:Potassium / Q000032:analysis; D013053:Spectrophotometry
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D011188:Potassium; D002118:Calcium; D008751:Methylene Blue