Deciphering Colonies of Phenotypic Switching-Derived Morphotypes of the Pathogenic Yeast Candida tropicalis

Abstract

Background Phenotypic switching generates fungal colonies with altered morphology and allows pathogens to adapt to changing environments.Objective This study investigated the structure of switched colonies in Candida tropicalis.Methods The switched variant strains (crepe and rough) were analyzed for colony morphology at the ultrastructural level-SEM. The distribution and composition of the extracellular matrix (ECM) were evaluated. The percentage of hyphae was determined by direct counting using light microscopy. The gene expression for these responses was measured by RT-qPCR. ResultsThe macromorphology of the switched variants exhibited high complexity, showing depressions, irregular edges, and a greater amount of ECM than the original strain. In addition, rough variant colonies showed higher amounts of total carbohydrates and proteins in ECM (p<0.05). We also observed a positive correlation between BCR1 (Bio lm cell regulator) gene expression and carbohydrate content in the rough variant (Pearson Correlation r²=0.9885, p=0.0483). Structured colonies exhibited a higher percentage of hyphae throughout their development (p<0.05). EFG1 (Enhanced lamentous growth protein 1) and WOR1 (White-opaque regulator 1) gene expression were positively correlated to the hyphae formation pro le of the structured and unstructured (original strain) patterns (r²>0.7673, p<0.05).Conclusion Structural variations in switched morphotypes colonies of C. tropicalis are associated with increased hyphae growth and distinction in composition and distribution of ECM. Switched phenotypes exhibit features that may contribute to the success of infection associated with C. tropicalis.

Phenotypic and genetic features of a novel clinically isolated rough morphotype Candida auris

“…These data strongly supported that the rough phenotypic variation of C. auris is likely to be related to the structural and functional changes in cell wall proteins. Recent studies have shown that switched morphotypes colonies of C. tropicalis have distinct expressions of the cell wall-associated master regulators genes ( de Souza et al, 2022 ).…”