Microsphaeropsis sp. was used to produce SCO in solid-state fermentation (SSF) from a substrate consisting of steam-exploded wheat straw (SEWS) and wheat bran (WB). The yield of SCO was 42 mg/g dry substrate (gds) without adding cellulase. To achieve a higher SCO yield, cellulase was added to the solid-state medium, resulting in an increase of SCO from 42 to 74 mg/gds with a cellulase loading of 10 FPU/gds. Other SSF parameters such as ratio of SEWS to WB of the dry substrate, initial moisture content, and incubation temperature were optimized under the condition of cellulase loading of 10 FPU/gds. So optimized, the SCO yield was 80 mg/gds, and the SCO content of the dry fermented mass was 10.2%. This research explored a novel method to produce SCO from the abundant and cheap agricultural residues - wheat straw and wheat bran. (c) 2007 Elsevier Ltd. All rights reserved.