Lignin degradation, metabolic profiling, and cold adaptation of Psychrobacter strain CLB018 isolated from the Antarctic fish Trematomus bernacchii.

Lignin, the second most abundant natural polymer on Earth after cellulose, is highly resistant to degradation, particularly in cold environments. In this study, a psychrotolerant bacterial strain, Psychrobacter faecalis CLB018, was isolated from the gut microbiota of the Antarctic fish Trematomus bernacchii near Zhongshan Station, Antarctica, using lignin as the sole carbon source at 4 ℃. Strain CLB018 exhibited high-efficiency lignin degradation, achieving a 40.39% degradation rate within 120 h at 10 ℃. It also demonstrated robust enzymic activities, producing lignin peroxidase (284 U/L at 48 h), laccase (111.9 U/L at 24 h), and manganese peroxidase (41.7 U/L at 48 h), essential for converting lignin into soluble aromatic compounds. Furthermore, CLB018 displayed versatility in utilizing diverse carbon source, including proteins, carboxylates, lipids, and aromatic compounds. Genomic analysis revealed the presence of genes encoding osmoprotectant transporters, cold shock proteins, an antioxidant system, and trehalose synthesis capability, which enhance its cold adaptation. These findings demonstrate that CLB018 possesses efficient lignin-degrading capabilities at low temperatures, highlighting its potential for sustainable biotechnological applications in cold environments. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-025-04623-9.