产耐热纤维素酶菌株的分子鉴定及产酶条件优化

从温泉热源地区采集的水样中筛选出1株60℃生长的纤维素酶产生菌NR615。通过ITS序列及系统发育进化树的分析表明该菌株为烟曲霉(Aspergillus fumigatus)。该菌株在28～60℃生长较好。对菌体及产酶条件进行优化得出:初始pH6.5,碳、氮源分别为结晶纤维素、牛肉膏时有利于产酶。其产生的纤维素酶的最适反应温度65℃,最适pH5.0,且在50～70℃有一定稳定的活性。经过响应面分析优化培养基,发酵5 d时活力达到2.411 3 IU/mL。这些特征表明,该菌株是1株性能良好的耐热纤维素酶生产菌株。

Molecular Identification and Characterization of a Thermostable Cellulase-Secreting Strain

A thermophilic strain NR615 possessing cellulase was isolated at 60℃ from hot spring samples.Based on the ITS sequence and phylogenetic tree analysis,strain NR615 was identified as Aspergillus fumigatus.The strain was capable of growing well at 28~60 ℃.According to optimization condition of cell growth and enzyme production,the initial pH is 6.5.The supernatant of strain incubated medium showed efficient activity of cellulase with addition of crystalline cellulose as carbon and beef extract as nitrogen sources respectively.The highest enzyme activity at 2.41 IU/mL was reached after incubation for 5d.The optimal pH of the celullase for the reaction is 5.0.This enzyme shows stable activity over a broad range of temperature from 50 ℃to 70 ℃.These characteristics of the cellulase demonstrated that it has potential application in the thermostable cellulase field.