Pellet size affects mycelial ergosterol content in aquatic hyphomycetes

Ergosterol was measured in mycelia of seven species of aquatic hyphomycetes grown in malt-extract broth. The harvested 21 d old pellets were grouped into 5-6 classes based on size, which were analyzed separately. In all but one species, there was a significant, positive correlation between the amount of ergosterol per unit mass and pellet diameter. Ignoring this correlation could result in the misleading conclusion that there is no relationship between mycelial mass and its absolute ergosterol content. The highest ergosterol concentrations were close to the average generally used to convert the amount of ergosterol in environmental samples to fungal biomass; the average was about half that value.