Isolation and identification of cellulose-decomposing microorganisms in Kobreasia capillifolia

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.