Ergosterol-to-Biomass Conversion Factors for Aquatic Hyphomycetes

Area of Science:

• Environmental microbiology
• Mycology
• Aquatic ecology

Background:

• Aquatic hyphomycetes are key decomposers of leaf litter in streams.
• Ergosterol is a reliable biomarker for fungal biomass quantification.
• Accurate biomass estimation is crucial for understanding stream ecosystem functioning.

Purpose of the Study:

• To quantify ergosterol content in common aquatic hyphomycete species.
• To evaluate the influence of different growth media on ergosterol concentrations.
• To propose conversion factors for estimating fungal biomass from ergosterol data.

Main Methods:

• Cultivation of 14 aquatic hyphomycete strains in three distinct liquid media.
• Analysis of total ergosterol content in fungal mycelium (mg/g dry mass).
• Statistical analysis of variations in ergosterol content across species and media.

Main Results:

• Ergosterol concentrations ranged from 2.3 to 11.5 mg/g dry mass, with an average of 5.5 mg/g.
• Significant differences in ergosterol content were observed among species and media, without a clear pattern.
• A general conversion factor of 182 is proposed for ergosterol to biomass conversion, with species-specific factors potentially improving accuracy.

Conclusions:

• Fungal ergosterol content is highly variable, influenced by both species and growth conditions.
• The proposed general conversion factor provides a baseline for biomass estimation, but species-specific factors are recommended for greater precision.
• Intraspecific variability may limit the accuracy of species-specific biomass estimations.