Metal-Resistant Mesophilic Laccase from Achromobacter Species: Identification, Physical Characterisation, and Dye...

Multicopper oxidases such as laccases have emerged as valuable biocatalysts in environmental and industrial processes due to their ability to oxidize a variety of phenolic and aromatic compounds using molecular oxygen as the sole electron acceptor. In the present study, laccase from different Achromobacter species, having close 16 S rRNA identity related to Achromobacter sp. strain 206,011 (accession no. MK949376.1), was screened. Maximum microbial growth and enzyme production were both observed at 24 h under optimized conditions. Optimum enzyme activity was observed at 40 °C and pH 5.0. The laccase maintained over 85% activity with metal ions up to 10 mM concentration, demonstrating strong metal tolerance and suitability for biotechnological applications in metal-rich environments. Partial purification of the crude enzyme revealed two prominent bands on SDS-PAGE, approximately at 50 kDa and 200 kDa, suggesting the possible presence of laccase isozymes. Native-PAGE further confirmed enzymatic activity through guaiacol oxidation. The laccase was subsequently evaluated for its bioremediation potential through dye decolorization assays, demonstrating promising activity across different dye types. These findings support the potential of this laccase as a robust biocatalyst for environmental applications, particularly in the treatment of dye-laden effluents.