Application and optimization of solid-state fermentation process for enhancing polygalacturonase production by Penicillium expansum

Penicillium expansum 3.5425 was applied in solid-state fermentation(SSF)of agricultural wastes for polygalacturonase biosynthesis.Among various carbon additives,apple pomace was most suitable for the biosynthesis of polygalacturonase(1440.57 U/g).Optimization of medium parameters using rotational orthogonal design(ROD)experiment combined with optimal fermentation conditions resulted in a 2.72-fold increase in the polygalacturonase production.By using ammonium sulphate precipitation,ion-exchange and gel-permeation chromatography,the polygalacturonase produced by P.expansum 3.5425 was finally purified which had specific activity of 19269 U/mg and molecular weight of 30 kDa.The enzyme was remarkably active in the pH range of 3-5 and at 50℃,which makes it more acceptable in the industrial application.Besides,partially purified polygalacturonase(875.15 U/mL)was used for apple juice clarification and the clarity at 0.4 mL/kg was maximum,which reveals a great potential of polygalacturonase in food industry.