Characterization of a novel thermophilic, cellulose-degrading bacterium Paenibacillus sp. strain B39

The aims of this study were to identify and characterize the novel thermophilic, cellulose-degrading bacterium Paenibacillus sp. strain B39. Strain B39 was closely related to Paenibacillus cookii in 16S rRNA gene sequence. Nonetheless, this isolate can be identified as a novel Paenibacillus sp. with respect to its physiological characteristics, biochemical reactions, and profiles of fatty acid compositions. A cellulase with both CMCase and avicelase activities was secreted from strain B39 and purified by ion-exchange chromatography. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the molecular weight of B39 cellulase was determined as 148 kDa, which was much higher than other cellulases currently reported from Paenibacillus species. The enzyme showed a maximum CMCase activity at 60°C and pH 6·5. Addition of 1 mmol l⁻¹ of Ca²⁺ markedly enhanced both CMCase and avicelase activities of the enzyme. We have identified and characterized a novel thermophilic Paenibacillus sp. strain B39 which produced a high-molecular weight cellulase with both CMCase and avicelase activities. Based on the ability to hydrolyse CMC and avicel, the cellulase produced by Paenibacillus sp. strain B39 would have potential applications in cellulose biodegradation.