Detoxification of steam-exploded corn straw produced by an industrial-scale reactor

Abstract

Steam explosion (SE) is widely used in lignocellulose pretreatment. However, steam-exploded corn straw (SECS) cannot be directly used as a solid-state fermentation substrate for Trichoderma reesei owing to the inhibitors released during pretreatment. We investigated the effect of SE conditions on inhibitor production in a 5 m 3 SE reactor and the fermentation enhancement achieved by drying and water-washing of SECS. The results reveal that SE enhanced the fermentability of corn straw and simultaneously produced fermentation inhibitors. Water-washing (corn straw/water 1:5, 60 °C, 2 × 30 min) removed 81% of the furfural and 85% of the phenol compounds from SECS pretreated at 1.6 MPa, which were higher than the 46 and 8.1%, respectively, removed by drying at 105 °C for 2 h. T. reesei YG3 cultures produced high cellulase activity of 41.4 and 81.4 IU/g dry medium on dried and water-washed SECS, respectively, which is higher than the 2.2 IU/g dry medium obtained from corn straw.