This study describes optimization of polygalacturonase (PG) production using Bacillus subtilis in submerged fermentation by Plackett-Burman (PB) design and response surface methodology (RSM). Five variables (pH, time, temperature, yeast extract concentration and K2HPO4), which were determined to be significant by the PB analysis, were further optimized using Box-Behnken response surface method. The optimization results indicated that a maximal PG activity of 5.60 U mL(-1) was achieved at pH 7.0, 72 h, and 30 degrees C using 0.5% (w/v) yeast extract and 0.02% (w/v) K2HPO4 in the fermentation medium. The results implied a 2.7-fold increase in PG activity of B. subtilis under the optimized conditions. Thus, it was concluded that hazelnut shell hydrolyzate have remarkable potential for low cost commercial PG production. (C) 2015 Elsevier B.V. All rights reserved.