Adapting an Ergosterol Extraction Method with Marine Yeasts for the Quantification of Oceanic Fungal Biomass

Katherine Salazar Alekseyeva, Barbara Mähnert, Franz Berthiller, Eva Breyer, Gerhard J. Herndl, Federico Baltar

Ergosterol has traditionally been used as a proxy to estimate fungal biomass as it is almost exclusively found in fungal lipid membranes. Ergosterol determination has been mostly used for fungal samples from terrestrial, freshwater, salt marsh- and mangrove-dominated environments or to describe fungal degradation of plant matter. In the open ocean, however, the expected concentrations of ergosterol are orders of magnitude lower than in terrestrial or macrophyte-dominated coastal systems. Consequently, the fungal biomass in the open ocean remains largely unknown. Recent evidence based on microscopy and -omics techniques suggests, however, that fungi contribute substantially to the microbial biomass in the oceanic water column, highlighting the need to accurately determine fungal biomass in the open ocean. We performed ergosterol extractions of an oceanic fungal isolate (Rhodotorula sphaerocarpa) with biomass concentrations varying over nine orders of magnitude. While after the initial chloroform-methanol extraction similar to 87% of the ergosterol was recovered, a second extraction recovered an additional similar to 10%. Testing this extraction method on samples collected from the open Atlantic Ocean, we successfully determined ergosterol concentrations as low as 0.12 pM. Thus, this highly sensitive method is well suited for measuring fungal biomass from open ocean waters, including deep-sea environments.

Functional and Evolutionary Ecology
Journal of Fungi
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
106021 Marine biology
ASJC Scopus subject areas
Microbiology (medical), Ecology, Evolution, Behavior and Systematics, Plant Science
Sustainable Development Goals
SDG 14 - Life Below Water
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