Enzymatic saccharification of pretreated wheat straw by T-reesei cellulases and A-niger beta-glucosidase

Three methods of wheat straw treatment (with NaOH, H2O2 and butylamine) and its subsequent saccharification by Trichoderma recsei cellulases and Asper gillus niger beta-glucosidase are reported. The treatment of straw with NaO H for Ih in the autoclave (120 degrees C) caused a great loss of the hemice llulose content and a partial removal of lignin, provoking an increase of t he cellulose content (from 24% to 69%) in the residue. When the straw was p re-treated with H2O2 at 25 degrees C for 20 h, the relative content of cell ulose in the straw increased (from 24% to 52%) due to the solubilisation of hemicellulose. The effect of varying the hydrolysis parameters (enzyme and substrate conce ntration, 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.