Optimization of hydrolases production by Penicillium crustosum in submerged fermentation using agro-waste residues as cosubstrate

Abstract

This study aimed to enhance the production of exo-polygalacturonases (exo-PG), xylanases, and endoglucanases using Penicillium crustosum through submerged fermentation. Lemon peel (LP) and wheat bran (WB) were examined as potential cosubstrate for hydrolase production. The highest exo-PG and endoglucanase activities were observed with LP, whereas xylanase activity showed improvement with the addition of WB. To optimize exo-PG and endoglucanase production, a 23 Face-Centered Central Composite Design (FCCCD) was employed, varying crucial physicochemical factors. Similarly, a 24 FCCCD was utilized to optimize xylanase production by varying temperature, pH, MnSO4 concentration as a cofactor, and the PDB culture medium. Under optimized conditions, exo-PG production reached 1427.99 ± 27.41 U/mL, marking a 45% increase compared to initial fermentation conditions. Endoglucanase production peaked at 62.68 ± 9.65 U/mL under conditions of 45 °C, pH 5.5, and 2.5 g/L MnSO4. Xylanase production reached 271.77 ± 8.50 U/mL under optimal conditions (37.5 °C, pH 5.5, 2.5 g/L MnSO4, and 62.5% PDB). The optimized simultaneous production of the hydrolytic cocktail occurred at 45 °C, pH 5.5, and 2.5 g/L MnSO4 with LP, yielding maximum activities of 959.74 U/mL for exo-PG, 61.98 U/mL for endoglucanases, and 65.60 U/mL for xylanases as determined by FCCCD. In conclusion, Penicillium crustosum shows promise as a hydrolase producer, and the utilization of agro-wastes as cosubstrate enhances the yield of enzymes with industrial relevance.