纤维素高效降解菌YN1的筛选及其降解特性

为了获得降解天然纤维素的微生物菌株,并用于农田秸秆腐熟及竹林地稻壳促腐。从牛羊粪堆肥中筛选出一株纤维素降解菌YN1,对其进行了形态和系统发育分析;测定了YN1的液、固体发酵酶活;进行了YN1对纤维素的失重测定;对YN1在纤维素表面上的定殖及其对纤维素的降解进行了电镜观察。经菌株形态分析和ITS基因序列分析,将YN1鉴定为曲霉(Aspergillussp.);在YN1菌株的液体发酵培养第3天,内切酶、外切酶、β-糖苷酶和总纤维素酶活性都达到最大值,分别为95.7、14.6、20.5和26.6U/mL,固体发酵培养第5d各酶活均达到峰值,依次为1192.2、100.6、136.9和210.7U/g;在失重测定中,YN1在7d内可降解41.87%的秸秆,31.59%的稻壳;在扫描电镜下可明显观察到YN1对滤纸、秸秆和稻壳的降解。YN1可有效降解天然纤维素,对农田秸秆腐熟及竹林地稻壳促腐具有较好的应用前景。

Isolation and Characterization of an Efficient Cellulose-decomposing Strain YN1

To obtain cellulose-decomposing strains, and to use them for decomposition of rice straw and rice hull. A cellulose-decomposing strain YN1 was isolated from cattle and sheep feces compost. Strain YN1 was identified by morphologic and phylogenetic analysis. Moreover, we performed the liquid and solid fermentation of YN1, and the degrading test of cellulose. In addition, scan electron microscope was used to observe the fixed propagation of YN1 on the cellulose and cellulose degradation. The morphologic and ITS gene sequence analysis suggested that YN1 was Aspergillus sp.. Through liquid fermentation, endoglucanases, exoglucanases, beta-glucosidases and the total cellulase activities reached to maximum at the 3th day, and they were 95.7, 14.6, 20.5 and 26.6 U/mL respectively. Though solid fermentation, the 4 kinds of cellulase activities reached to maximum at the 5th day, and they were 1192.2, 100.6, 136.9 and 210.7 U/g respectively. In the degrading experiment, YN1 could degrade 41.87% of rice straw, 31.59% of rice hull in weight in 7 days respectively. The remarkable phenomenon that YN1 degrading crude cellulose could be observed by scan electron microscope. YN1 showed value of practical applications in rice straw and rice hull decomposition.