线叶嵩草内生产纤维素酶细菌分离及初步鉴定  

Isolation and identification of cellulose-decomposing microorganisms in Kobreasia capillifolia

作　　者：李振东[1,2] 陈秀蓉[1] 杨成德[1] 李鹏[1] 

机构地区：[1]甘肃农业大学草业学院草业生态系统教育部重点实验室甘肃省草业工程实验室中-美草地畜牧业可持续发展研究中心,甘肃兰州730070 [2]甘肃省社会科学院农村发展研究所,甘肃兰州730070

出　　处：《草业科学》2014年第1期48-55,共8页Pratacultural Science

基　　金：国家自然基金项目(31160122);草业生态系统教育部重点实验室(甘肃农业大学)开放课题(CYzs-2011011)

摘　　要：以东祁连山高寒草地优势牧草线叶嵩草（Kobresia capillifolia）为对象, 分离和筛选纤维素分解内生细菌, 并对产纤维素酶的条件进行了优化。结果表明, 从线叶嵩草内分离到6个内生细菌的菌株, 其中2个菌株具有分解纤维素的能力, 并重点研究了菌株X5, 其纤维素溶解圈直径与菌落直径比达10.45, 初始产生的纤维素酶活性为0.456 U, 经优化, 产纤维素酶的最佳培养条件为：蛋白胨和酵母粉各5 g·L^-1, 羧甲基纤维素钠5 g·L^-1, pH值8.5, 培养温度20 ℃, 酶活性达0.862 U;菌体杆状, 大小为（0.66～0.92）μm×（1.67～2.43）μm, 革兰氏阳性, 产芽孢;结合形态特征、生化特性和16S rDNA序列鉴定为球形芽孢杆菌（Bacillus sphaericus）。Endophytic cellulose-decomposing bacteria were isolated from Kobreasia capillifolia which is dominant grass on alpine grassland in the Eastern Qilian Mountains. All of the isolated bacteria strains were screened and identified. At the same time, the conditions of producing cellulose were optimized by orthogonal test. Totally, there were 6 endophytic bacteria strains isolated from K.capillifolia and only two of them --X5 and X6 can decompose cellulose. Only strain X5 were further analysis as its potential cellulase enzymatic activity which was 0.456 U. And the ratio of the diameter between lysis zone and colony diameter of strain X5 was up to 10.45. The optimum culture conditions for producing cellulose were 5 g·L^-1 peptone, 5 g·L^-1 yeast powder, 5 g·L^-1 sodium carboxymethylcellulose, pH 8.5 and 20 ℃ culture temperature . Cellulase enzymatic activity of strain X5 was 0.862 U after optimization, which was the 1.89 times of that before optimization. Strain X5 was Rod-shaped with a size of （0.66-0.92） μm×（1.67~2.43） μm, Gram-positive, and can produce spores. Based on these physiological and biochemical characteristics and 16S rDNA gene sequence analysis, X5 were identified as Bacillus sphaericus.

关 键 词：高寒草地 内生细菌 球形芽孢杆菌 纤维素酶 16S RDNA 

分 类 号：S812[农业科学—草业科学]