Intracellular pH homeostasis in Candida glabrata in infection-associated conditions

Candida glabrata is an opportunistic fungal pathogen which is a growing concern for immunocompromised patients. It is ranked as the second most common cause of candidiasis after Candida albicans. For pathogenic yeasts, intracellular pH (pH(i)) has been implicated in proliferation, dimorphic switching and virulence. We expressed the pH-sensitive green fluorescent protein variant ratiometric pHluorin in the cytosol of C. glabrata to study pH(i) dynamics in living cells. We evaluated the response of pH(i) to the various growth and stress conditions encountered during interaction with the host and during antifungal treatment. C. glabrata maintained a pH(i) higher than that of Saccharomyces cerevisiae in all growth conditions. The pH(i), of S. cerevisiae cells appeared better controlled than the pH(i) in C. glabrata when the cells were exposed to food and fermentation-associated conditions. C. glabrata in turn maintained its pH(i) better when exposed to host-associated conditions.