Bioprocessing of wheat straw was carried out by Phlebia brevispora under solid state conditions. Effect of different supplements on lignocellulolytic enzymes production, degradation of straw cell wall fibers and its resultant effect on nutritional quality of wheat straw were studied. Ammonium chloride and malt extract were more effective in terms of ligninolysis and enhanced in vitro digestibility. The concentration of the selected supplements and the moisture content was worked out using response surface methodology in order to minimize the loss in total organic matter so as to selectively degrade lignin. The experiment was scaled up to batches of 200 g under optimized conditions and the degraded substrate was analyzed for its biochemical properties. P. brevispora degraded 290 g/kg of lignin and enhanced the in vitro digestibility from 150 to 268 g/kg (78%). Crude protein, amino acids, total phenolic contents and antioxidant properties were significantly higher in degraded straw. (C) 2011 Elsevier Ltd. All rights reserved.