Newly Isolated Penicillium sp. for Cellulolytic Enzyme Production in Soybean Hull Residue

Abstract

(1) Background:

The aim of this study was to evaluate the production and partial characterization of xylanase and avicelase by a newly isolated Penicillium sp. in solid-state fermentation, using soybean hulls as substrate.

(2) Methods:

Temperature, time, number of spores, and substrate moisture on xylanase and avicelase bioproduction were evaluated, maximizing activity with 30°C, 1x10⁶ spores/g substrate, 14 and 7 days of fermentation with 70 and 76% substrate moisture contents, for xylanase and avicelase, respectively.

(3) Results:

Different solvents, temperatures, and agitation in the enzymatic extraction were evaluated, obtaining higher activities, 430.77 and 26.77 U/g for xylanase and avicelase using 30 min extraction and 0.05 M citrate buffer solution (pH 4.5 ), respectively at 60°C and 175 rpm and 50°C and 125 rpm. The optimum pH and temperature for enzymatic activity determination were 5.3 and 50°C. Enzyme extract stability was evaluated, obtaining higher stability with pH between 4.5 and 5.5, higher temperature of up to 40°C. The kinetic thermal denaturation (K_d), half-life time, D-value, and Z-value were similar for both enzymes. The xylanase Ed value (89.1 kJ/mol) was slightly lower than the avicelase one (96.7 kJ/mol), indicating higher thermostability for avicelase.

(4) Conclusion:

In this way, the production of cellulases using alternative substrates is a way to reduce production costs, since they represent about 10% of the world demand of enzymes, with application in animal feed processing, food production and breweries, textile processing, detergent and laundry production, pulp manufacturing and the production of biofuels.

Keywords:
Xylanase; avicelase; solid-state fermentation; partial characterization; enzymatic thermostability