Abstract: The degradation of wheat bran by Bacillus licheniformis(Bacillus sp. X18) was studied by means of measuring concentrations of reducing sugar and soluble total sugar, activities of cellulase and hemicellulase in fermented broth, weight loss, crystallinity, FT-IR spectra and surface structure of residue. The results showed that the process of biodegradation of lignocellulose is actually simultaneous saccharification and fermentation. Cellulase and hemicellulase activities reached the highest level in 96 and 48 h, respectively. Concentrations of soluble total sugar and reducing sugar reached the highest level in 4 and 48 h,at 5257.79 and 1363.94 mg/L, respectively, and then decreased with time and maintained invariable value. Crystallinity of residue had no obvious change after 5 d cultivation. FT-IR spectrum of residue showed that Bacillus sp. X18 mainly degradated cellulose in wheat bran. After 5 d cultivation degradation rates of cellulose, hemicellulose and lignin in wheat bran were 37.03%, 15.86% and 17.03%, respectively. SEM of surface structure of degradated wheat bran by Bacillus sp. X18 showed that constituent serving function of support in framework of honeycombed structure was mainly degradated.

Key words: Bacillus licheniformis, wheat bran, cellulase, degradation