Optimization of Culture Conditions for Xylanase Production from Cellulase-free Xylanase-producing Thermophilic Fungus, Thermomyces dupontii KKU−CLD−E2−3

Abstract

The thermoalkaliphilic cellulase-free xylanase-producing fungi, Thermomyces dupontii KKU−CLD−E2−3 was isolated from elephant dung. The production of thermo-alkali-stable and cellulase-free xylanase of the fungus was optimized in solid-state fermentation using statistical approaches. Response surface methodology (RSM) using central composite design (CCD) was employed to optimize conditions. The maximum xylanase production was observed at a 1.72% nitrogen concentration, initial pH of 10.54, initial moisture content of 74.73% and under incubation for 8 days at a temperature of 43.93 ºC. The maximum xylanase activity was evaluated at pH 11.0 and retained over 80% of the original activity within a pH range of 7.0–10.0 after incubation at 4 ºC for 24 h. In addition, the optimum temperature for xylanase activity was 80 ºC. The enzyme also retained more than 80% of its residual activity after heated at 60 ºC for 90 min. Therefore, its properties demonstrate significant promise for use in pulp bleaching for the paper industry; for which this study will be the focus of future investigation.