Abstract: Laccases from Pleurotus ostreatus were extracted from the Shaken flask cultures of Pleurotus ostreatus   grown at 25 °C with continuous agitation (110 r.p.m.) in baffled 1000 ml Erlenmeyer flasks containing 200 ml medium. The basal GYP medium used for cultures unless otherwise stated contained 20 g glucose l-1, 5 g yeast extract l-1, 5 g peptone from casein l−1 and 1 g MgSO₄.7H₂O l−1. The pH was adjusted to 5.0 with H₃PO₄ prior to sterilization. The kinetics of oxidation reactions catalyzed by laccases was studied using ABTS. The laccases showed lower specific activity and higher activity in non-polar organic solvents. Enzyme modified electrodes were fabricated with polyaniline. Electrochemical polymerization of aniline was performed to get the film of polymer on the surface of glass electrode. First ITO/PANI electrode was reduced by a 15 min cathodic polarization of the sensor at -500mV in 0.1M acetate buffer, pH 5.5. After cathodic polarization, the film was immersed in 0.1M of acetate buffer, pH 5.5 containing enzyme solution for the deposition of enzyme in polymer layer at +650mV for 20 min. During this oxidation process Laccases become electrostatically attached to polymer film. The ITO/PANI/LAC electrode was rinsed with deionised water to remove any loosely bounded enzyme, and stored in buffer solution at 40 C when not in use. Conducting polymer/enzyme modified electrodes prepared by immobilization of enzyme were tested for electrocatalytic activities towards Amperometric sensing of phenol in industrial Effluent.
 

Key words: Polyaniline, laccases, biosensor, phenol