P52: Optimization of xylanase production in Penicillium pinophilum using Plackett-Burman design

Penicillium pinophilum ATCC 200401 is a potent mutant strain for production of lignocelluloses-degrading enzymes such as cellulase and xylanase. The objective of this work was to optimize xylanase production in this strain in shake flask cultures. Eleven fermentation variables - pretreated corn stover (PCS), birchwood xylan (BWX), soybean meal, yeast extract, corn steep liquor (CSL), ammonium sulphate, urea, potassium dihydrogen phosphate (KH₂PO₄), pH, inoculum size and incubation time - were screened using Plackett-Burman design. Out of that, three variables of significance in xylanase production - soybean meal, CSL and inoculum - were selected and further optimized via response surface methodology based on central composite design. Their optimal values in xylanase production were 3.11% (soybean meal), 0.10% (CSL), and 4.94% (inoculum). Under these conditions, a maximum xylanase activity of 457.58 U/ml was obtained which was in good agreement with the predicted value of the quadratic model (457.16 U/ml) thereby confirming the validity of the model. In addition, the adequacy of the model was supported by a coefficient of determination (R²) of 0.82. As a result of the optimization of the three fermentation parameters, the xylanase production in the optimized medium increased 89% over that in the non-optimized medium (242.92 U/ml). The P. pinophilum xylanase is currently examined for its potential to assist in hydrolysis of plant biomass for biofuels production.