Assessment of the atmospheric fungal prevalence through field ergosterol measurement I—Determination of the specific ergosterol content in common ambient fungal spores and yeast cells

This and a companion paper report a means to assess fungal prevalence in ambient air by measuring the ergosterol concentration. The results are highly reproducible. Twelve species and strains of fungal spores and yeast cells commonly found in ambient air in the subtropics were cultured in the laboratory. Gas chromatography–mass spectrometry (GC–MS) was used to determine their ergosterol content. (1) The specific ergosterol content of the 12 species ranged from 0.047 to 9.919 pg (spore or yeast cell)−1. (2) It was found that the larger the surface area of the spore/yeast cell, the higher the specific ergosterol content. (3) The specific ergosterol content of the spores or cells increased during vegetative growth of the parent cells, but became steady once the parent had matured. (4) Ergosterol was found to decompose in autoclaved spores or yeast cells, but a substantial amount of the ergosterol remained. Therefore, ergosterol can be used to reflect both the viable and the non-viable fungal mass. In a companion paper, an empirical general conversion factor for determining fungal concentration from field ergosterol measurements is proposed.