Unveiling the Chemical Composition and Biological Activity of Extracts from the Antarctic Yeast Dioszegia sp. AL105 and Bannozyma sp. AL104

The extreme Antarctic environment offers unique living conditions. The organisms inhabiting Antarctica have a specific metabolism through which they overcome the challenges of large temperature amplitudes, long periods of light or darkness, and intense UV radiation. Microorganisms are ubiquitous in Antarctica and have been the subject of intensive research in recent decades. In this manuscript, two yeast species were isolated from Antarctic habitats and identified as Dioszegia sp. AL105 (AL105) and Bannozyma sp. AL104 (AL104). The cultivation of these two species under submerged conditions were evaluated. The strain AL104 managed to accumulate over 7 g/L biomass for 96 h. For the first time, the cytotoxic activity of the obtained yeast extracts on malignant cell lines has been studied. The obtained methanol and acetone extracts showed different cytotoxicity when used to treat different malignant cell lines, with maximal values of IC50 = 113 ± 8.2 established for the HUT-78 line with AL104. The methanol extracts of both yeast species exhibited low antibacterial activity against Staphyloccocus aureus, MRSA, and Escherichia coli. Additionally, the methanol extract of AL105 inhibited the biofilm formation of MRSA to a higher extent than the methanol extract from AL104. Antioxidant activities were determined by using HPSA, HRSA, and NOSA tests. The chemical characterization of the extracts showed the presence of various lipids—CoQ10, triglycerides, phosphatidylethanolamine, and ceramide. It is likely that the interaction between the different bioactive molecules can explain the observed cytotoxicity. The current new studies have proven that Antarctic yeasts are a potential source of biologically active molecules with the potential for future biomedical research.