Abstract

Sunflower sludge was used as the sole carbon source for xylanase production, an important industrial enzyme used in pulp and paper industry, by the fungi Trichoderma harzianum MTCC 4358. Sunflower sludge was subjected to alkaline pretreatment which showed higher enzyme activity than the substrate used without pretreatment. The effect and significance of the medium components were studied using the Plackett-Burman design. The experimental xylanase activity was subjected to statistical analysis using MINITAB 15 software. It was found that peptone, urea, CaCl₂.2H₂O, Tween 80, (NH₄)₂.SO₄, MgSO₄.7H₂O and MnSO₄ significantly influenced xylanase production (8.63 U/g of dry substrate). The enzyme showed maximum activity at pH 5 (8.75 U/g of dry substrate), 45°C (8.66 U/g of dry substrate) and 80% initial moisture content (8.84 U/g of dry substrate) and a period of 7 days incubation (8.57 U/g of dry substrate) was necessary for maximum enzyme production. Under these optimized physical conditions and in optimized medium T. harzianum MTCC 4358 was inoculated and subjected to ultrasonication for every 12 h (for a period of 8 days), which resulted in higher enzymatic activity of 9.27 U/g of dry substrate.

Key words: Xylanase, Trichoderma harzianum, ultrasonication, sunflower sludge, Plackett-Burman design.