Title
Statistical optimization of cellulase production by Trichoderma longibrachiatum on wheat bran under solid-state fermentation utilizing Plackett-Burman design
Authors
HIND LEGHLIMI, FATIMA-ZOHRA KENZA LABBANI, AICHA BELMESSIKH, NAIMA BOUTAGHANE and ZAHIA KABOUCHE

Received February 18, 2026
Published Volume 60 Issue 3-4 March-April
Keywords cellulase, Trichoderma longibrachiatum, solid-state fermentation, wheat bran, Plackett-Burman design, enzyme optimization

Abstract
Cellulases are essential industrial enzymes extensively utilized in biofuel production, textile processing, and waste management. However, high production costs limit their widespread commercial application. This study aimed to optimize cellulase production by Trichoderma longibrachiatum isolate under solid-state fermentation (SSF) using wheat bran, an abundant and inexpensive substrate. Fermentation parameters were first optimized using a one-factor-at-a-time (OFAT) approach, identifying 30 °C and 2 × 107 spores per gram of dry substrate (gds) as optimal conditions. Subsequently, medium components affecting enzyme production were statistically evaluated using a Plackett-Burman design comprising eight experimental runs with five variables: carboxymethyl cellulose (CMC), ammonium sulfate ((NH₄)₂SO₄), MgSO₄·7H₂O, FeSO₄·7H₂O, and ZnSO₄·7H₂O. Statistical analysis demonstrated that CMC, (NH₄)₂SO₄, FeSO₄·7H₂O, and ZnSO₄·7H₂O significantly enhanced filter paper activity (FPA) (p < 0.001). Endoglucanase activity (EGA) showed a significant positive correlation with CMC and (NH₄)₂SO₄ (p < 0.001). Pareto charts confirmed that CMC and (NH₄)₂SO₄ were the most influential factors for cellulase production. Under optimized conditions, wheat bran was found to be an effective substrate for producing high cellulase titers with low operational cost. These findings highlight the potential of combining agricultural residues with statistical optimization to advance cost-effective enzyme production and support sustainable bioconversion technologies.