Osmolytes and Lipids of the Conidia of the Xerohalophilic Micromycete Aspergillus penicillioides

Abstract—

Investigation of the lipid and osmolyte composition in conidia of the xerohalophile Aspergillus penicilloides grown on media with high NaCl and glycerol concentrations is important for the understanding of the functions of these compounds in the adaptation of the extremophile. Conidia of the fungus grown on a medium with glycerol contained up to 15% of the dry mass of carbohydrates and polyols (CaP) of the cytosol, with predominance of glycerol (60% of the total) in their composition, while on a medium with salt, the proportion of glycerol did not exceed 20% and the amount of CaP was 10%. On both media, the proportion (20%) and amount (2.5%) of trehalose were the same; the proportion of polyols was thus about 80%, although their composition was different, indicating a possible synergy between trehalose and polyols in adaptation. Both variants of conidia were characterized by a low content of both membrane and storage lipids represented mainly by triacylglycerides. Phosphatidylcholines and sterols were the predominant membrane lipids of the fungal conidia, regardless of the composition of the medium, which indicated high stability and conservatism of the lipid bilayer. The constancy of the composition of membrane and storage lipids and their low content, the high level of CaP, and significant differences in their composition indicate the key role of osmolytes in the adaptation of fungal conidia to various environmental conditions.