Genomic and Phenotypic Analysis of Antarctic Marine Cryobacterium sp. PAMC25264.

Antarctic marine environments are extreme cold ecosystem and the microbes inhabiting them play a crucial role in ecosystem function. In this study, genomic and phenotypic analysis of Cryobacterium sp. PAMC25264, isolated from seawater of Barton, South Shetland Island, Antarctica Peninsula was performed. Comparative genomic analysis with related strains focused on nitrogen metabolic enzymes, carbohydrate-active enzymes (CAZymes) and stress-related proteins to elucidate the functional diversity and survival strategy of the strains in these harsh environments. Type Strain Genome Server (TYGS) analysis suggest that this strain may represent a distinct phylogenetic lineage within the genus Cryobacterium. Nitrogen metabolic enzymes including respiratory nitrate reductase (α, β, γ, and δ subunits), assimilatory nitrate reductase (NasA), nitrate/nitrite transporter (NarK/U), assimilatory nitrite reductase (NirB and NirD), and glutamate synthase (GltB and GltD) were identified from genomic analysis. dbCAN3 revealed the presence of a total of 125 CAZymes. Among them 66 glycoside hydrolases (GHs), 36 glycosyltransferases (GTs), 6 carbohydrate esterases (CEs), 15 carbohydrate-binding modules (CBMs), and 2 polysaccharide lyase (PL). In addition, proteins related to oxidative stress (superoxide dismutase, catalase, and thiol peroxidase), temperature stress (Csp and Hsp), and heavy metal(loid)s (HMMs) resistance were identified. Furthermore, the strain exhibited nitrate reduction in aerobic condition, resulting in nitrite accumulation, starch hydrolysis, and cellulose hydrolysis ability at different temperatures (4 °C, 10 °C, 15 °C, and 25 °C). Overall, these genomic and phenotypic traits indicate metabolic flexibility and functional diversity, supporting its survival and potential ecological role in extreme cold marine ecosystems.