Purification and germination of Candida albicans and Candida dubliniensis chlamydospores cultured in liquid media

Abstract

Candida albicans and Candida dubliniensis are the only Candida species that have been observed to produce chlamydospores. The function of these large, thick-walled cells is currently unknown. In this report we describe the production and purification of chlamydospores from these species in defined liquid media. Staining with the fluorescent dye FUN-1 indicated that chlamydospores are metabolically active cells, but that metabolic activity is undetectable in chlamydospores that are greater than 30 days old. However, 5-15 day old chlamydospores could be induced to produce daughter chlamydospores, blastospores, pseudohyphae and true hyphae depending on the incubation conditions used. Chlamydospores that were pre-induced to germinate were also observed to escape from murine macrophages following phagocytosis, suggesting that these structures may be viable in vivo. Mycelium-attached and purified chlamydospores rapidly lost their viability in water and when subjected to dry stress, suggesting that are unlikely to act as long-term storage structures. Instead, our data suggest that chlamydospores represent an alternative specialised form of growth by C. albicans and C. dubliniensis.