To minimize environmental contamination and waste of resources, distillers' grain (DG) from the Chinese liquor industry was used to produce reducing sugars for Bacillus thuringiensis cultivation. Four different pretreatments, using sodium hydroxide (0.5-2% w/v, 50-121 degrees C, 1 h), calcium hydroxide (0.2-4% w/v, 50-121 degrees C, 1 h), dilute sulfuric acid (0.5-2% w/v, 50-121 degrees C, 1 h), and hot water (50-121 degrees C, 1 h), were investigated in order to determine the optimal method for degrading cellulose in DG to produce monomeric sugars. Enzymatic hydrolysis and fermentation followed each pretreatment method. The results showed that the highest yield of monomeric sugars was obtained by using 2% dilute sulfuric acid treatment at 121 degrees C for 1 h (giving 313 g/kg DG), which was significantly higher (p < 0.001) than the yields obtained using other pretreatment methods. The highest spore count was achieved using this pretreatment with the addition of supplements. The utilization of DG in this study provides a plentiful carbon source that is effective not only for cultivating microorganisms but also for reducing industrial waste.