Characteristics of Candida albicans metabolism of glucose and two sugar substitutes, xylose and xylitol and effect of these substitutes on glucose metabolism from a cariogenic perspective

Objectives Carbohydrate metabolism and subsequent acid production of Candida albicans remain insufficiently understood. C. albicans may utilize xylitol, but its cariogenic implications are understudied. This study examined growth and metabolism of glucose, xylitol and precursor xylose by C. albicans and their effects on glucose metabolism.Methods C. albicans JCM1537 was cultured in YNB medium containing 1% glucose, xylose, xylitol or xylose- or xylitol-glucose combinations. Acid production from cells grown on each substrate was assessed by pH-stat system at pH 7.0 using 10 mM substrates. Metabolic end-products were quantified by HPLC and enzymatic methods. Carbon recovery and redox balance of glucose metabolism were calculated stoichiometrically.Results Growth and acid production on xylose or xylitol were much lower than on glucose, with no inhibitory effect of xylose or xylitol observed. Glucose carbon was distributed as 50.48% ethanol, 21.95–24.72% bicarbonate, 5.70% glycerol, 2.88% organic acids and 0.12% acetaldehyde, yielding 81.07–84.48% recovery and 93.26–93.97% reduction–oxidation balance.Conclusions Although xylose and xylitol did not inhibit C. albicans glucose metabolism, their limited growth and acidogenicity suggest low cariogenic potential. The overall view of glucose metabolism, including high ethanol production, provides new insights into the metabolic impact of C. albicans within the oral microbiome.