Abstract: This work aims to screen the strains that can degrade Glycyrrhiza uralensis residues（GUR）and to optimize the production process of cellulase by the strains. First，the strains were screened from decayed Glycyrrhiza uralensis and soil，and then were identified through morphological observation and 18S rDNA. Second，the effects of different factors on the fermentation of the isolated strains were studied，and the orthogonal test L9（34）was used to determine the optimal condition of producing enzyme. The produced cellulase complex was used to investigate how the enzymatic hydrolysis of GUR was proceeding. According to the results，the isolated strain was identified as Penicillium oxalicum，designated as G2. The effects of concentrations of herb residues and fermentation time on cellulase production of G2 were significant（P<0.05 and P<0.05）. Under the optimal conditions，the FPase activity reached 3.43 U/mL and EG activity reached 16.89 U/mL. Compared with commercial cellulase，the cellulase by G2 was more efficient in degrading GUR. In addition，the extraction rate of total flavonoids from Glycyrrhiza uralensis Fisch was significantly higher after enzymatic hydrolysis. Here screening the GUR-degrading bacteria and studying the process of producing the enzyme from the GUR laid the foundation for the rational utilization of GUR and the production of cellulase with low cost and fine performance.

Key words: Glycyrrhiza uralensis residues, cellulase, Penicillium oxalicum