Sugarcane bagasse was used as substrate for xylanase production by means of a strain of Trichoderma harzianum Rifai isolated from decaying Aspidosperma sp. (peroba) wood. The bagasse was washed, dried, milled and wetted with minimal salts medium and the cultures grown at 28 ± 2ºC for 7 days. Two extraction methods were tested for enzyme recovery: (A) Tween 80, 0.1% (v/v), in physiological saline, and (B) 50mM sodium acetate buffer, pH 5.0, under agitation (180rpm) for 15, 30 and 60min. After a single extraction, both extraction methods recovered an average of 15U/ml of xylanase activity, independent on the time of shaking. A second and third extraction recovered 10.4 and 6.6U/ml xylanase, respectively. The effect of volume size for extraction, and sugarcane bagasse concentration, on xylanase production were also investigated. The growth profile of Trichoderma harzianum was followed over 20 days on 14% (w/v) bagasse, and highest xylanase activity (288U/ml) appeared on the seventh day. The enzymatic extract after precipitation with ammonium sulphate was submitted to electrophoresis on polyacrylamide gels and showed 4 protein-staining bands, one of which exhibited xylanase activity.
Trichoderma harzianum; xylanase; solid state fermentation; sugarcane bagasse
