Influence of oxidative and osmotic stresses on the structure of the cell wall mannan of Candida albicans serotype A

In this study, we investigated the structural changes in the cell wall mannan of Candida albicans serotype A strain cells cultured under various stress conditions, that is, oxidative stress of 3.5 mM H₂O₂, osmotic stress of 1.5 M NaCl, and heat stress at 37 °C, compared with the normal condition of 30 °C in yeast extract-added Sabouraud liquid medium (YSLM). Based on the ¹H nuclear magnetic resonance (NMR) and fluorophore-assisted carbohydrate electrophoresis (FACE) analyses of the mannans, we showed that the proportion of the terminal β-1,2-linked mannose side chain unit in the mannan increased in the cell proliferation process under both the normal condition and the oxidative stress condition. The osmotic stress induced a slight decrease in the proportion of the β-1,2-linked mannose unit in the acid-labile fraction. The heat stress induced a significant decrease in the proportions of the β-1,2-linked mannose unit in both the acid-labile and acid-stable fractions. Based on these results, we propose that C. albicans significantly changes the mannan structures under various stress conditions and that sufficient attention to the cultural conditions is needed to perform an accurate diagnosis of candidiasis.