Abstract Xylanases assume special importance in the paper and pulp
industry as they replace toxic chemicals such as chlorine and chlorine
dioxide for developing eco-friendly processes. This study evaluated
xylanases produced by two fungi, the mesophilic fungus Trichoderma
harzianum and a thermophilic fungus Chaetomium thermophilum . Among
the polymeric substrates studied for xylanase production by both the
fungi, birch wood xylan was found to be the best inducer of xylanases.
Xylanases induction was subject to glucose repression. Partially
purified xylanases preparation from T. harzianum and C. thermophilum
exhibited optimal activities at pH 5 and 6 and at 60\ubaC and
70\ubaC, respectively. The apparent Km and Vmax values for the
partially purified xylanase from T. harzianum using oat spelt xylan as
a substrate were 4.8 mg mL-1 and 0.526 \u3bcmol min-1 mg-1,
respectively. Whereas values of the partially purified xylanase from C.
thermophilum were 2.96 mg mL-1 and 0.25 \u3bcmol min-1 mg-1,
respectively. These findings in this study have great implications for
the future applications of xylanases