为分离高效降解纤维素的菌株，以羧甲基纤维素钠为唯一底物，从腐熟的苹果树枝条中选择性分离到24株真菌，利用刚果红染色法初筛测定，发现有8株菌具有产胞外纤维素酶的能力。对初筛试验中透明圈/菌落直径较大的菌株进行纤维素酶活测定，最终获得1株高效产胞外纤维素酶的菌株10，其滤纸酶活性、内切酶活性、外切酶活性分别达到13.26、36.67、12.06 IU。基于分子生物学鉴定和系统发育分析，表明该菌株为土曲霉(Aspergillus terreus)。通过单因素优化发酵条件，得到该菌最适产酶培养条件为pH=7、羧甲基纤维素钠含量1.25%、硝酸钠含量1.50%，优化后其滤纸酶活性、内切酶活性、外切酶活性达到27.80、57.30、29.10 IU，分别比优化前提高了109.65%、56.26%、141.29%。菌株10能够高效产生胞外纤维素酶，为果树枝条的腐熟利用和纤维素酶的工业化开发提供了高效菌株。

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.