A new xylanase from a Trichoderma harzianum strain

A new xylanase (XYL2) was purified from solid-state cultures of Trichoderma harzianum strain C by ultrafiltration and gel filtration. SDS-PAGE of the xylanase showed an apparent homogeneity and molecular weight of 18 kDa. It had the highest activity at pH 5.0 and 45 degrees C and was stable at 50 de grees C and pH 5.0 up to 4 h xylanase. XYL2 had a low K-m with insoluble oa t spelt xylan as substrate. Compared to the amino acid composition of xylan ases from Trichoderma spp, xylanase XYL2 presented a high content of glutam ate/glutamine, phenylalanine and cysteine, and a low content of serine. Xyl anase XYL2 improved the delignification and selectivity of unbleached hardw ood kraft pulp.