Oxidation of Coniferyl Alcohol Catalyzed by Laccases from Trametes versicolor.

ABSTRACT

Oxidation of coniferyl alcohol catalyzed by commercial laccase and crude laccase produced during the submerged cultivation of Trametes versicolor MZKI G-99 in a medium containing the waste from paper industry was investigated. pH of 6.6 and temperature of 35 °C was found to be optimal for coniferyl alcohol oxidation catalyzed by commercial laccase. Based on the initial reaction rate measurements, apparent Michaelis-Menten kinetic parameters for commercial laccase were determined in an aqueous media (Vm = 4.387 U mg-1, Km = 0.025 mmol dm-3), as well as in 11 (v/v) methanol phosphate buffer mixture (Vm = 0.979 U mg-1, Km = 0.019 mmol dm-3). Inhibition of substrate was found for crude laccase and the following apparent kinetic parameters Vm = 9.272 U mg-1, Km = 0.045 mmol dm-3 and Ki = 0.002 mmol dm-3 were estimated. Mathematical model of batch process, which includes double-substrate Michaelis-Menten kinetics with oxygen as the second substrate and mass balances, has been developed and validated in experiments with or without additional aeration. 100 % conversions of up to 0.8 mmol dm-3 of coniferyl alcohol in batch experiment due to the high operational stability of enzymes was realized with both laccases.