Sterols of melanized fungi from hypersaline environments

The lipid compositions of melanized fungi isolated from calcite, gypsum and halite depositional environments of Mediterranean solar salterns, namely Hortaea werneckii, Alternaria alternata, Cladosporium cladosporioides, Cladosporium sp. and Aureobasidium pullulans, have been examined. Sterols constituted the most distinct lipid fraction. Ergosterol, 24-methylcholesta-5,7,22-trien-3β-ol, dominated all distributions but major differences between species were encountered when considering the subordinate sterols. Thus, 24-methylcholest-7-en-3β-ol, 24-methylcholesta-7,24(28)-dien-3β-ol and 4α,24-dimethylcholest-7-en-3β-ol were found in significant proportions in Cladosporium spp (14–20%), A. alternata (28%) and H. wernekii (29%), respectively. These sterols can be used for discrimination between these different fungal species. 24-Methylcholest-7-en-3β-ol and 24-methylcholesta-7,24(28)-dien-3β-ol were found in significant proportion in the water column particles and sediments of the gypsum and halite precipitation ponds (the latter only in the halite domain). In such environments, these sterols may provide a specific signature for these melanized fungi. However, water column particulate matter and sediments from hypersaline depositional settings show sterol compositions dominated by the constituents typically encountered in phytoplankton and zooplankton, but not in melanized fungi.