Harnessing recombinant Bacillus licheniformis CotA laccase for electrochemical detection of catechol

Laccases, known for their ability to oxidize a broad range of substrates and catalyze multiple reactions, offer tremendous potential for varied applications. Despite their widespread presence in nature, research has primarily focused on fungal laccases. However, fungal laccases are susceptible to extreme conditions and inhibitors, hindering their widespread industrial use. Under such circumstances, a burgeoning interest has surrounded extremophilic and cost-effective bacterial laccases. Consequently, we explored the potential of recombinant Bacillus licheniformis laccase (CotA) in the fabrication of an electrochemical biosensor for the detection of catechol, an environmental pollutant. The biosensor was constructed by modifying a screen-printed electrode with CotA encapsulated in a conducting polymer (PEDOT:PSS)/chitosan film. CotA can oxidize catechol, and this step enabled the detection of catechol through amperometric measurements. The biosensor demonstrated competitive analytical features to fungal laccases with a low detection limit (1.4μM), high sensitivity (42.637 μAmM^-1) and excellent storage stability retaining 90 % of its initial activity after 40 days of storage at 4 °C. Furthermore, it successfully detected catechol in spiked tap and river water samples making it an effective and efficient solution for monitoring catechol in real environmental samples.