Cloning and characterization of a novel cold-active endoglucanase establishing a new subfamily of glycosyl hydrolase family 5 from a psychrophilic deep-sea bacterium.

The gene of a novel endo-ß-1,4-glucanase (named Cel5M) was isolated from the psychrophilic deep-sea bacteria Pseudomonas sp. MM15. The deduced protein sequence lacked the typical cellulase domain structures of the carbohydrate-binding module and the linker region. Cel5M showed relatively higher activity toward carboxymethyl cellulose, but much lower activity toward p-nitrophenyl-ß-D-galactopyranoside and no activity toward avicel. Cel5M was identified as a cold-active cellulase with an optimal temperature of 30 °C and it was active within a narrow pH range with an optimum at pH 4.5. Phylogenetic analysis showed that Cel5M represented a new subfamily of the glycosyl hydrolase family 5, representing an opportunity for research into and applications of novel cold-active cellulases.