Candida albicans cells exhibit media specific proteomic profiles during induction of filamentation

Candida albicans is an opportunist pathogen responsible for a broad spectrum of infections, from superficial mycosis to the systemic disease candidiasis. C. albicans has various morphological forms, including unicellular budding yeasts, filamentous pseudohyphae and true hyphae, and the ability to switch from yeast to hyphal forms is a key survival mechanism underlying the adaptation of the pathogen to the microenvironments encountered within the host. Filamentation is regulated by multiple signalling pathways and its induction in different growth media in vitro has often led to conflicting results. In this study, we performed quantitative proteomic analyses to compare the response of C. albicans yeast cells grown in YNB minimal medium to those of cells grown in four media widely used in the literature to induce the yeast-to-hyphae transition: YNB-Serum, YNB-N-acetylglucosamine (YNB-NAG), Lee medium and rich Spider medium. We show that each growth medium induces a unique pattern of response in C. albicans cells, and that some conditions trigger an original and specific adaptive metabolic response, showing significant differences in the intracellular content of the various filamentous forms. Moreover, this comparison of proteomic profiles indicates that the medium used can modify the thiol-dependent redox status of the cells, particularly in YNB-Serum and Lee medium and, to a lesser extent, in Spider medium, confirming the role of oxidative stress in the filamentation process. Overall, our data indicate that some of the media routinely used to induce hyphae cause significant changes in proteomic signature that should be taken account more carefully when exploring the hyphal transition in this pathogen.