Abstract—Adaptive reactions of Arctic and Antarctic strains of psychrophilic micromycetes Geomyces pannorum and Thelebolus microsporus to growth within a broad temperature range were studied. Adaptation of these species to different temperatures was found to result from both morphological and biochemical changes, including changes in the concentration of small molecules and lipid membrane components. These biochemical, morphological, and physiological mechanisms exhibited the patterns common to all strains, as well as species and strain differences. The general patterns included temperature-dependent changes in amounts of monosaccharides, some disaccharides, and free linoleic and linolenic acids. The differences between the Arctic and Antarctic strains were mainly associated with the differences in lipid composition, while interspecies differences resulted from metabolomic modifications. Antarctic strains showed lower ability to survive elevated temperatures, which correlated with weaker manifestation of the lipid-dependent adaptive mechanisms compared to the Arctic strains. Among the interstrain differences, higher growth parameters and mannitol accumulation were found in the Arctic isolates. Adaptation of T. microsporus was characterized by more diverse changes in the concentrations of small organic molecules in the metabolome profile and by pronounced changes in mycelial morphology. The results of metabolomic analysis and their subsequent treatment by the methods of multivariant statistics supported the suggestion of higher dispersion of metabolomic characteristics under unfavorable conditions and of lower dispersion of metabolomic data under optimal conditions.