一株产纤维素酶的耐热烟曲霉筛选及产酶条件研究

Screening of a thermotolerant cellulase-producing Aspergillus fumigatus strain and study on the conditions for cellulase production

从土壤中分离和筛选到1株产纤维素酶能力较强的耐热真菌E4。通过菌株的形态特征和18S rDNA序列同源性比较,该菌株被鉴定为一种烟曲霉(Aspergillus fumigatus)。实验结果表明,该菌株能在20℃以下生长,其最适和最高生长温度分别为40℃和55℃。该菌株的最佳产纤维素酶的基质为稻草,其最适产酶pH值为5.0,最适产酶温度为42℃。50℃摇瓶培养72h时可达到产酶最高峰,其羧甲基纤维素酶(CMCase)活和滤纸酶(FPA)活分别达到3.5U/mL和3.2U/mL。该菌株对稻草的降解效果较好,45℃液体摇床培养条件下在7d内对天然稻草的降解率达63.5%。

A thermotolerant cellulase-producing fungal strain E4 was isolated from the soil. E4 was identified as Aspergillus fumigatus by morphologi- cal characteristics as well as by the 18S rRNA gene sequence. Experimental results show that it can grow at 20℃, and the optimum and supreme growth temperature was 40℃ and 55℃, respectively. The best enzyme production conditions is straw as fermentation mediums. The optimal enzyme production pH was 5.0, and the temperature is 42℃. The maximum CMCase （hydroxyl methyl cellulose enzyme） activity is 3.5U/mL, and the maxi-mum FPA （filter paper enzyme） activity is 3.2U/mL after fermentation with shaking flask for 72h at 45℃. The strain could effectively degradate the straw and the degradation rate reached 63.5% in 7d.