Hydrolysis of xylans by enzyme systems from solid cultures of Trichoderma harzianum strains

Xylanase activity was isolated from crude extracts of Trichoderma harzianum strains C and 4 grown at 28 degrees C in a solid medium containing wheat b ran as the carbon source. Enzyme activity was demonstrable in the permeate after ultrafiltration of the crude extracts using an Amicon system. The hyd rolysis patterns of different xylans and paper pulps by xylanase activity r anged from xylose, xylobiose and xylotriose to higher xylooligosaccharides, A purified beta-xylosidase from the Trichoderma harzianum strain released xylose, xylobiose and xylotriose from seaweed, deacetylated, oat spelt and birchwood xylans, The purified enzyme was not active against acetylated xyl an and catalyzed the hydrolysis of xylooligosaccharides, including xylotrio se, xylotetraose and xylopentaose. However, the enzyme was not able to degr ade xylohexaose. Xylanase pretreatment was effective for hardwood kraft pul p bleaching. Hardwood kraft pulp bleached in the XEOP sequence had its kapp a number reduced from 13.2 to 8.9 and a viscosity of 20.45 cp, The efficien cy of delignification was 33%.