Pseudohyphae formation in Candida glabrata due to CO2 exposure

BACKGROUND AND PURPOSE Formation of pseudohyphae is considered a virulence factor in Candida species. Generally, Candida glabrata grows as budding yeast cells; however, reports illustrated that C. glabrata could form pseudohyphal cells in response to some stimuli. In this study, we provided insight into the ability of C. glabrata in forming pseudohyphal cells under different levels of carbon dioxide (CO2). MATERIALS AND METHODS Candida glabrata reference strain (ATCC 90030) was used in this study. Yeast samples were cultured on Sabouraud dextrose broth (SDB) medium and incubated under 3%, 5%, and 10% CO2 levels for 24, 48 and 72 h. Control cultures were prepared without CO2 pressure for three days. The possibility of pseudohyphae and mycelium formation in C. glabrata was investigated. RESULTS The results of this study revealed that the most branching filament-like cells were obtained at high CO2 pressure (10%) after 72 h. After three days of low CO2 pressure (3%), only yeast and budding cells were observed without any pseudohyphae formation. CONCLUSION CO2 could act as a stimulus and induced formation of pseudohyphae in Candida glabrata yeast cells.