Abstract
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°C, 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. Keywords: solid-state fermentation (SSF), polygalacturonase, Penicillium expansum, juice clarification, agricultural wastes DOI: 10.25165/j.ijabe.20181106.3673 Citation: Zhu M M, He H J, Fan M T, Ma H J, Ren H W, Zeng J, et al. Application and optimization of solid-state fermentation process for enhancing polygalacturonase production by Penicillium expansum. Int J Agric & Biol Eng, 2018; 11(6): 187–194.
Highlights
In the industrial area, pectinase is a common term of enzyme groups providing three different catalytic activities which catalyze various pectin and pectic substances[1,2]
Banana peels, wheat straw, wheat bran, sugarcane bagasse, rice straw and soybean hulls have been used as the substrates for enzyme production[2,20]
It is better to select a low-cost solid substrate which provides all necessary nutrients for microbial growth and desired enzyme production
Summary
Pectinase is a common term of enzyme groups providing three different catalytic activities (hydrolysis, de-esterification or trans-elimination) which catalyze various pectin and pectic substances[1,2]. Polygalacturonase, as one of the most important pectinases, has been widely used in fruit or vegetable juices processing procedures, including maceration, liquefication, extraction, and clarification. SSF, as an increasingly growing technology for enzyme production, has a series of advantages over submerged fermentation such as less water and solvent requirement, more favorable conditions for fungal growth, lower liquid waste generation, higher concentration and larger amount of enzyme production. These advantages achieved special economic interest from those industries with abundance of biomass and agro-industrial residues[6,7], in particular fruits processing industry. The selection and optimization of substrates and culture condition are necessary to decrease industrial costs for enzymatic biosynthesis[9]
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