Candida dubliniensis and Candida albicans display surface variations consistent with observed intergeneric coaggregation

Mary Ann Jabra-Rizk, William A. Falkler, William G. Merz, Jacqueline I. Kelley, A. A.M.A. Baqui, Timothy F. Meiller

Research output: Contribution to journalArticlepeer-review

Abstract

Adherence of yeasts to other microorganisms and epithelial cell surfaces is important in their colonization. Comparative studies based on the coaggregation of Candida dubliniensis versus candida albicans with Fusobacterium nucleatum and other oral bacteria suggested differences in the surfaces of these yeasts. TransmisSion electron microscopy was used to test the hypothesis that there are morphologic variations in the cell surface of these two species. C. dubliniensis type strain CD36 and C. albicans ATCC 18804 were grown on Sabouraud's dextrose agar at various growth temperatures. In some experiments suspensions of yeast cells were treated with dithiothreitol. Fixation for transmission electron microscopy was accomplished using dimethylsulfoxide and alcian blue added to 3% paraformaldehyde and 1% glutaraldahyde in cacodylate buffer. The cell wall of both species was predominantly electron lucent and was visibly differentiated into several layers. A thin electron dense outer layer was seen with clearly visible fibrillar structures, closely associated to the cytoplasmic membrane. The length of the fibrils of the C. albicans cells grown at 37°C was approximately two times greater than those of the cells grown at 25°C. The fibrils of the 37°C-grown cells were thin, distinct and tightly packed whereas those of the 25°C-grown cells appeared blunt, loosely spaced and aggregated. C, dubliniensis demonstrated short, blunt fibrils appearing similar to those of the 25°C-grown C. albicans cells. C. dubliniensis showed no difference in the density, length and arrangement of fibrils between the 25°C and 37°C growth temperatures. The shortest and most aggregated fibrils seen were of the 45°C-grown C, albicans cells. Dithiothreitol-treated 37°C- grown C. albicans cells revealed a distorted and partially destroyed fibrillar layer. In this investigation C. dubliniensis, unlike C. albicans, displayed an outer fibrillar layer that did not vary with variations in growth temperature. In addition, the fibrils on the C. dubliniensis cells were similar to those of the 25°C-grown C. albicans in that they were considerably shorter and less dense than those of the 37°C-grown C. albicans cells. It can be postulated, that C, dubliniensis exhibits constant cell surface characteristics consistent with hydrophobicity and that this property may give this species an ecological advantage. Therefore, C. dubliniensis may compete well in oral environments via enhanced attachment to oral microbes and other surfaces, perhaps even more efficiently than C. albicans.

Original languageEnglish (US)
Pages (from-to)187-193
Number of pages7
JournalRevista Iberoamericana de Micologia
Volume16
Issue number4
StatePublished - Dec 1999

Keywords

  • Candida albicans
  • Candida dubliniensis
  • Cell wall
  • Electron microscopy

ASJC Scopus subject areas

  • Microbiology
  • Infectious Diseases

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