Enzymatic Saccharification of Pretreated Wheat Straw byT. ReeseiCellulases andA. Nigerβ-Glucosidase

Three methods of wheat straw treatment (with NaOH, H2O2 and butylamine) and its subsequent saccharification by Trichoderma recsei cellulases and Aspergillus niger beta-glucosidase are reported. The treatment of straw with NaOH for Ih in the autoclave (120 degrees C) caused a great loss of the hemicellulose content and a partial removal of lignin, provoking an increase of the cellulose content (from 24% to 69%) in the residue. When the straw was pre-treated with H2O2 at 25 degrees C for 20 h, the relative content of cellulose in the straw increased (from 24% to 52%) due to the solubilisation of hemicellulose. The effect of varying the hydrolysis parameters (enzyme and substrate concentration, temperature and pH) was studied in order to maximise the yield of sugars. Under the best conditions and after 48 h with a mixture of 2: 1 (w/w) cellulase/beta-glucosidase (with a concentration of 7 and 0.1 Uml(-1), respectively) the native, NaOH-treated and H2O2-treated straw material were degraded to reducing sugars for 28%, 89% and 97% respectively.