Differential Increase in Cytoplasmic PH at Bud and Germ Tube Formation in Candida Albicans: Studies of a Nongerminative Variant

The changes in cytoplasmic pH (pHi) accompanying the morphological transition of Candida albicans were studied using a nongerminative variant. A transient cytoplasmic alkalinization at the time of evagination was observed in both the variant and its parent. Under zinc-deficient conditions the wild-type cells that formed buds at pH 4.5 and mycelia at pH 6.5 showed an increase in pHi of 0.58 and 0.12 pH units, respectively. Under similar conditions the pHi of the nongerminative variant that formed buds at both pH 4.5 and 6.5 increased by 0.66 and 0.40 pH units, respectively, suggesting that a greater magnitude of increase in pHi at the time of evagination is probably needed for bud formation. These results provide evidence for a correlation between intracellular alkalinization and time of cell differentiation in C. albicans.