Effect of elevated temperatures and low levels of trace metals on the growth and phenotypic development of Candida albicans.

A combination of elevated temperatures (within the human febrile range) and trace metal chelation were investigated for their effects on the inhibition of growth and phenotypic development of the dimorphic yeast Candida albicans (strain 3153A). The ability of specific cations to relieve the phenotypic inhibition that occurred also was tested. Elevated temperatures alone (to 41 degrees C) only delayed the timing of the phenotypic development. When compared to the results obtained at 37 degrees C, the recombination of elevated temperature and addition of the trace metal chelator, 1,10-phenanthroline, did not further suppress phenotypic development, but the combination did decrease the viability of C. albicans. When 24 to 48 h stationary phase singlet cells were released into a medium containing 100 microM 1,10-phenanthroline (pH 6.5), supplemental iron (200 microM) alleviated the suppression of mycelium formation at 41 degrees C, whereas under conditions favoring bud formation (pH 4.5), both iron and zinc circumvented suppression and promoted budding. Through studies on the interaction of temperature stress and trace metal availability our data revealed the requirement for iron mycelium formation whereas both iron and zinc may be needed for bud formation.