Miscanthus was pretreated with the fungus Ceriporiopsis subvermispora under non-sterile conditions, using sterile miscanthus that had been previously colonized with the fungus as the inoculum. Inoculum ratios equal to or greater than 30% yielded a successful pretreatment, enhancing the enzymatic digestibility of miscanthus by 3- to 4-fold over that of raw miscanthus, which was comparable with the fungal pretreatment under sterile conditions. This enhanced digestibility was linearly correlated with lignin degradation. Although cellulose loss of up to 13% was observed for the successful non-sterile pretreatments, the final glucose yield was 3- 4 times higher than that of raw miscanthus and comparable to that of the sterile pretreated miscanthus. A time course study showed that maximum glucose yield can be achieved with a pretreatment time of 21 days. (C) 2015 Elsevier Ltd. All rights reserved.