Metabolism of [14C]Glucose by Regenerating Spheroplasts of Candida albicans

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Abstract
Spheroplasts of C. albicans were regenerated in [14C]glucose and buffered MgSO4 (0.1 M-Tris/HCl; 0.5 M-MgSO4, pH 7.2) at 35.degree. C. Uptake of glucose by spheroplasts was faster than that by intact yeast cells. After 6 h, 65% of the glucose taken up by the yeast appeared as CO2 and 30% was incorporated into the cellular material. With spheroplasts, 55% of the glucose taken up was expired as CO2, 25% was excreted into the medium as other metabolites an 20% was incorporated into the cells. The regenerating spheroplasts excreted 14C-labeled carbohydrates into the medium which were fractionated on a Sephadex G-15 column. Acid hydrolysis of the low-MW fraction yielded the following sugars: mannose (75.7%), fucose (3.8%), arabinose (3%), galactose (2.1%) and an unidentified monosaccharide (14%). Spheroplasts did not incorporate mannoprotein into the regenerated wall. The wall carbohydrate from regenerated spheroplasts was fractionated on the basis of solubility in sodium hydroxide. The alkali-insoluble fraction was analyzed by sequential enzyme hydrolysis; 40% of the incorporated counts were associated with .beta.(1 .fwdarw. 3)-linked glucan and 50% with a mixed glucan comprising .beta.(1 .fwdarw. 3)- and .beta.(1 .fwdarw. 6)-linkages and chitin.