Feruloyl esterase (FAE) and xylanase activities were detected in culture supernatants from Humicola grisea var. thermoidea and Talaromyces stipitatus grown on brewers' spent grain (BSG) and wheat bran (WB), two agro-industrial by-products. Maximum activities were detected from cultures of H. grisea grown at 150 rpm, with 16.9 U/ml and 9.1 U/ml of xylanase activity on BSG and WB, respectively. Maximum FAE activity was 0.47 U/ml and 0.33 U/ml on BSG and WB, respectively. Analysis of residual cell wall material after microbial growth shows the preferential solubilisation of arabinoxylan and cellulose, two main polysaccharides present in BSG and WB. The production of low-cost cell-wall-deconstructing enzymes on agro-industrial by-products could lead to the production of low-cost enzymes for use in the valorisation of food processing wastes. (C) 2007 Elsevier Ltd. All rights reserved.