Enhanced pectinase production by optimizing fermentation conditions of Bacillus subtilis growing on hazelnut shell hydrolyzate

• Plackett–Burman and response surface methods were used for optimization of pectinase production.
• Hazelnut shells used as carbon source were shown to be an appropriate low cost material for enzyme production.
• Pectinase production has been enhanced by 2.7-fold after optimization.

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 °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.

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