Genomic resources of Cold-adapted Mrakia yeasts and their potential biotechnological applications.

Mrakia is a cold-adapted yeast genus commonly found in polar environments, including the Antarctic and Arctic regions. Several Mrakia genome sequences have been reported to date; however, comprehensive genomic analyses remain limited. Further, there are no reports of complete mitochondrial genome sequences for the genus Mrakia. Therefore, we isolated two cold-adapted yeast strains, Mrakia gelida PAMC 26583 and Mrakia robertii PAMC 26600, from Arctic lichens. Phylogenetic analysis placed both strains within the order Cystofilobasidiales. High-quality whole-genome assemblies were generated using Nanopore long-read and Illumina short-read sequencing, resulting in nearly complete nuclear and mitochondrial genomes. Analyses of gene family expansion and contraction revealed lineage-specific enrichment in functions associated with nucleosome assembly, DNA repair, metal ion binding, and membrane transport. Functional annotation identified numerous carbohydrate-active enzymes and peptidases with potential industrial applications. Both strains also exhibited ethanol production under low dissolved oxygen conditions, underscoring their utility in low-temperature fermentation. Notably, the mitochondrial genome annotation presented here represents the first reported for the order Cystofilobasidiales, providing valuable taxonomic insights into the class Tremellomycetes. These genomic resources will support future evolutionary studies and the development of biotechnological applications involving cold-active enzymes and low-temperature fermentation.