Optimization of biopolymerization rate by response surface methodology (RSM)

Response surface methodology was successfully applied to enzymatic biopolymerization of catechol, which was conducted in a closed system containing acetone and sodium-acetate buffer, with laccase enzyme to produce poly(catechol). Laccase enzyme used as catalyst was derived from Trametes versicolor (ATCC 200801). The enzymatic biopolymerization rate of catechol, based on measurements of initial dissolved oxygen (DO) consumption rate in the closed system, was optimized by the application of response surface methodology (RSM). The independent variables, which had been found the most effective variables on the initial DO consumption rate by screening experiments, were determined as medium temperature, pH and acetone content. A quadratic model was developed through RSM in terms of related independent variables to describe the DO consumption rate as the response. Based on contour plots and variance analysis, optimum operational conditions for maximizing initial DO consumption rate, while keeping acetone content at its minimum value, were 31 °C of temperature, pH 4.87 and acetone content of 13.5% to obtain 0.128 mg DO/min L for initial oxidation rate. The FT-IR spectrum of the poly(catechol) produced revealed that catechol units in the enzymaticaly produced polymer were combined with each other via ether linkage.