Research Article Characterization of glycolytic metabolism and ion transport of Candida albicans Martha Calahorra*, Norma Silvia Sánchez and Antonio Peña Department of Molecular Genetics, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, DF México *Correspondence to: M. Calahorra, Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, DF, 04510 México. E-mail: mcalahor@ifc.unam.mx Received: 20 January 2012 Accepted: 10 July 2012 Abstract The main energetic pathways, fermentation and respiration, and the general ion transport properties of Candida albicans were studied. Compared to Saccharomyces cerevisiae, we found that in C. albicans: (a) the cell mass yield when grown in YPD was significantly larger; (b) it required longer times to be starved of endogenous substrates; (c) ethanol production was lower but significant; (d) respiration was also lower; (e) it showed a small activity of an alternative oxidase; (f) fermentation and oxidative phosphorylation seemed to compete for both ADP and NADH; and (g) NADH levels were lower. Regarding ion transport and compared to S. cerevisiae: (a) the general mechanism was similar, with a plasma membrane H + -ATPase that generates both a plasma membrane ΔpH and a ΔΨ, the latter being responsible for driving K + inside; (b) its acidification capacity is slightly smaller and less sensitive to activation by high pH; and (c) the presence of K + results in a large activation of both respiration and fermentation, most probably due to the energy required in the process. ADP produced by H + -ATPase stimulation by high pH or the addition of K + at low pH results in the increase of both respiration and fermen- tation. Copyright © 2012 John Wiley & Sons, Ltd. Keywords: Candida albicans; fermentation; glycolysis; yeast ion transport Introduction Candida albicans is a dimorphic fungus in which the yeast-to-mycelium transformation is influenced by a variety of environmental factors. It is a ubiqui- tous commensal and infections with this fungus are a particular problem in immune-compromised patients. Most work on the general metabolism and transport properties of Candida albicans has been carried out around isolated aspects. Since the sensitivity of this species to antifungal drugs is dependent on respiratory conditions (Dumitru et al., 2004), much work has been done in this aspect. As in other Candida species, mitochondria contain three respiratory chains: the classical respiratory chain (CRC), a secondary parallel chain (PAR) and an ‘alternative’ oxidative pathway (AOX) (Kot et al., 1976; Shepherd et al., 1978; Aoki and Ito-Kuwa, 1984; Milani et al., 2001; Helmerhorst et al., 2002; Cavalheiro et al., 2004; Ruy et al., 2006). The accumulation of K + during hyphae formation has also been studied (Watanabe et al., 2006). C. albicans has been described as a poor fermentor (Rozpedowska et al., 2011). In a recent schematic representation of its metabolism, although focused on morphogenesis, pyruvate decarboxylase and alcohol dehydrogenase were not even considered (Han et al., 2011). Regarding ion transport, specific studies have been performed, such as the existence of a plasma membrane H + -ATPase, described and characterized by Hubbard et al. (1986) and then further studied by Mahanty et al. (1990) and Gupta et al. (1991, 1992). In addition, a Na + /H + antiporter has been described in both C. albicans and C. dubliniensis (Krauke and Sychrova, 2008). Yeast Yeast 2012 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/yea.2915 Copyright © 2012 John Wiley & Sons, Ltd.