Study on degradation of rice straw by Bacillus licheniformis
一株地衣芽孢杆菌对稻草降解作用的研究

The degradation of rice straw by Bacillus licheniformis was studied, by measuring activities of cellulase and hemi-cellulase, concentration of reducing sugar and soluble total sugar in fermented broth, weight loss, crystallinity, FT-IR and surface structure of residue. The results showed that the process of biodegradation of lignocellulose is actually simultaneous saccharification and fermentation. Cellulase and hemi-cellulase activities reached highest level in 12 h and 48 h, respectively. Concentration of soluble total sugar reached highest level in 4 h, and then decreased with time and maintained invariable level, Meanwhile concentration of reducing sugar decreased with fermentation and then maintained invariable level. Crystallinity of residue had not obvious change after 5 d cultivation. FT-IR spectrum of residue showed that B. licheniformis degraded cellulose, hemi-cellulose and lignin in rice straw in some extent,After 5 d cultivation, the degradation ratio of cellulose, hemi-cellulose and lignin in rice straw were 14.91%, 6.61% and 1.42%, respectively. Scanning electron microscope observation of surface structure of degraded rice straw by B. licheniformis showed that thin-walled cell of rice straw became wrinkled and wizen.