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Updated: Aug 14, 2026
A New Method for Qualitative Multi-scale Analysis of Bacterial Biofilms on Filamentous Fungal Colonies Using Confocal and Electron Microscopy
Published on: January 25, 2017
Scanning electron microscopy of colonies of six species of Candida
Abstract:
Thirty strains of six species of Candida isolated from patients were cultured for 60 h on Sabouraud agar, freeze-dried, and examined with a scanning electron microscope. The colonies were circular (Candida albicans, C. guilliermondii) or oval (C. tropicalis, C. pseudotropicalis, C. krusei, C. parakrusei) in outline, and those of C. pseudotropicalis and C. krusei had an irregular outline due to a peripheral pseudomycelium. The morphology of individual microorganisms was examined at the margins and apex of those species which lacked a surface coat (C. pseudotropicalis, C. krusei, C. parakrusei, C. guilliermondii), and through cracks in the surface coating of those which showed a surface coat (C. albicans, C. tropicalis). All species showed buds, bud scars, and interconnecting intercellular processes, but were generally spherical (C. albicans, C. tropicalis) or ovoid (C. pseudotropicalis, C. krusei, C. parakrusei, C. guilliermondii) in fixed preparations. In unfixed material, individual organisms were almost invariably indented. Fixation with 3% glutaraldehyde and washing before freeze-drying caused partial removal of the surface coating of colonies of C. albicans and C. tropicalis, which persisted only as irregular sheets or as a filamentous meshwork. This filamentous meshwork was also present among the organisms of colonies of C. albicans, C. tropicalis, and C. pseudotropicalis. It is concluded that these filaments represent the precipitation or unmasking of some component of the intercellular matrix of these organisms.
Insights
Scanning electron microscopy revealed distinct colony morphologies and intercellular structures in six Candida species. These findings highlight the extracellular matrix
Area of Science:
- Microbiology
- Mycology
- Cell Biology
Background:
- Candida species are opportunistic fungal pathogens.
- Understanding Candida morphology is crucial for diagnostics and treatment.
Purpose of the Study:
- To characterize the surface morphology of six Candida species using scanning electron microscopy.
- To investigate the ultrastructure of Candida colonies and individual cells.
Main Methods:
- Culturing of 30 Candida strains (six species) on Sabouraud agar for 60 hours.
- Freeze-drying of colonies followed by examination with scanning electron microscopy.
- Microscopic analysis of colony outlines, individual cell morphology, and extracellular structures.
Main Results:
- Colonies exhibited circular or oval outlines, with some species showing peripheral pseudomycelium.
- Individual Candida cells displayed buds, bud scars, and intercellular processes.
- A filamentous meshwork, likely representing the intercellular matrix, was observed in several species, particularly C. albicans and C. tropicalis.
Conclusions:
- Distinct morphological differences exist among Candida species at the colony and cellular levels.
- The observed filamentous meshwork suggests the presence and potential unmasking of an intercellular matrix component.
- These ultrastructural findings contribute to the understanding of Candida biology and interactions.
