Cold-adapted yeasts for hydrocarbon degradation: bioremediation insights from extreme environments

Cold-adapted yeast strains were isolated from Continental Antarctic soils through hydrocarbon-based enrichment and characterized for their potential in low-temperature hydrocarbon degradation. Molecular identification revealed the isolates as Rhodosporidiobolus odoratus, Rhodotorula mucilaginosa, and Filobasidium magnum. Growth assays on 30 carbon (C) and 5 nitrogen (N) sources at 10 °C revealed differential metabolic traits among the strains, with F. magnum exhibiting the broadest substrate assimilation profile, including hexadecane utilization. Gas chromatography–mass spectrometry (GC-MS) was employed to evaluate the hydrocarbon-degrading capacity of the isolates in Bushnell-Haas broth supplemented with spent engine oil. The initial composition of the oil was dominated by C20–C50 alkanes (78%), with minor fractions of methyl esters (11%), polycyclic aromatic hydrocarbons (PAHs; 5%), BTEX compounds (3%), C1–C20 alkanes (2%), and alkylbenzenes (1%). After 30 days of incubation at 10 °C, significant differences in degradation efficiency were observed among the strains. R. odoratus significantly reduced long-chain alkanes, whereas both R. odoratus and F. magnum decreased PAHs and aromatic derivatives. F. magnum achieved the lowest residual relative abundance of BTEX and alkyl biphenyls. In contrast, R. mucilaginosa showed limited degradation capacity and in some cases, an accumulation of aromatic intermediates. These findings indicate that the yeast isolates R. odoratus and F. magnum exhibit promising hydrocarbon-degrading activity across multiple compound classes, including both aliphatic and aromatic hydrocarbons. Hydrocarbon degradation by cold-adapted microorganisms therefore represents a sustainable strategy to mitigate petroleum pollution in extreme environments such as Antarctica and any other cold regions with polar or alpine climate, where low temperatures and nutrient scarcity constrain natural attenuation processes.