关键词: 纤维素酶, 真菌, 鉴定, 优化, 酶活性

Abstract: In order to isolate the highly efficient cellulose-degrading strain,a total of 24 fungi isolates were obtained from the decomposing fruit tree branches by using the dilution isolation method, with sodium carboxymethyl cellulose as the sole carbon substrate.Eight fungi strains were found to produce extracellular cellulase.Strains with larger hydrolytic circle/colony diameter in preliminary tests were selected to detect their celluase activities,and the results indicated strain 10 with highest activities.Its filter paper enzyme activity,endonuclease activity and exonuclease activity reached 13.26,36.67 and 12.06 IU respectively.Based on molecular and phylogenetic analyses, the strain was identified as Aspergillus terreus. Next the fermentation conditions through single factor optimizing were improved,and the optimal culture conditions for the three enzymes production were pH=7,the sodium carboxymethyl cellulose content=1.25%,and the sodium nitrate content=1.50%.After optimization,the filter paper enzyme activity,endonuclease activity and exonuclease activity reached 27.80,57.30,29.10 IU,which increased by 109.65%,56.26%,141.29% compared to pre-optimization,respectively.The highly efficient cellulase producing fungus strain 10 was provided for fruit branches fermentation and cellulase industrial development.

Key words: Cellulase, Fungi, Identification, Optimization, Enzyme activity