[Isolation, identification and cellulase production of a cellulolytic bacterium from intestines of giant panda].

OBJECTIVE: To isolate and identify the cellulose-producing bacterium from fresh feces of healthy giant pandas, and characterize its cellulase production.
METHODS: A strain with high activity of cellulase was isolated and purified by carboxymethyl cellulose-Na (CMC-Na) medium. The morphological, physiological and biochemical characteristics and 16S rDNA gene were analyzed to identify the taxonomic position of the strain. Meanwhile, its cellulase producing conditions and degradation of several cellulose substrates were studied.
RESULTS: A cellulose-producing strain P2 was obtained. Strain P2 is a gram-positive and aerobic bacterium. Its growth temperature ranges from 20 to 50 degrees C (optimum at 37 degrees C) and pH 6.0 to 9.0 (optimum at 7.0), and NaCl concentration at 0%-15% (optimum at 2.0%). It took 24 h to reach the peak of cellulase production. Phylogenetic analysis based on 16S rDNA sequence showed that strain P2 is most closely related to the Bacillus amyloliquefaciens NBRC15535 with the similarity of 99. 66% . Strain P2 posses different abilities to degrade four different cellulose substrates including filter paper, absorbent cotton, straw, and bamboo fiber. During the degradation, it shows different enzymatic activity curves with endoglucanases, exoglucanases, beta-glucosidases and cellulase.
CONCLUSION: An aerobic cellulolytic bacterium was isolated from feces of giant pandas for the first time, and was identified as Bacillus amyloliquefaciens. Due to its ability to degrade the cellulose materials with different structures, strain P2 could be used in the further study on the digestion mechanism of bamboo of giant panda.