A novel halophilic laccase from Halomonas elongata: Purification, characterization, and application in green synthesis of salicylic acid.

This study presents the successful one-step purification and characterization of a novel laccase derived from Halomonas elongata, an extremophilic bacterium with promising applications in industrial biocatalysis. The enzyme was purified using a Cu@FeO-NH@GA hybrid affinity support, exhibiting a specific activity of 377.8 U mg and a molecular weight of ~75 kDa. Characterized by halophilic properties, the laccase exhibited maximum activity at pH 9 and in the presence of 1.5 mM NaCl, demonstrating remarkable stability in organic solvents and against various inhibitors. The enzyme was successfully applied to the green synthesis of salicylic acid from its alcohol precursor, achieving an 89.9 % yield under optimized conditions: 325.9 U mL laccase, 15.8 mM TEMPO, 36 % solvent-to-buffer ratio, and 38.7 °C. These findings demonstrate the potential of this newly identified laccase as a promising biocatalyst for industrial applications, particularly in eco-friendly organic synthesis.