The marine bacterium Saccharophagus degradans 2-40 produces a multicomponent cellulolytic system composed of ten annotated GH5 endoglucanases, two GH9 endoglucanases and several cellodextrinases, cellobiohydrolase, glucanases and phosphorylases during growth on cellulose. To establish their biochemical activities, two apparent paralogous CBM6&GH5-carrying β-1,4-endoglucanases, Cel5G and Cel5H, were cloned into pET28b to create N and C terminal 6x His tags to the full length polypeptide as well as to ΔCBM derivatives. Each was expressed in E. coli Rosseta™ and purified to apparent homogeneity using a combination of affinity and size exclusion chromatography. The specific activity of each expressed protein was determined on soluble and partially crystalline substrates, such as 4-nitrophenol β-D cellobioside, carboxylmethylcellulose (CMC), phosphoric acid swollen cellulose, Avicel and filter paper. Typical of CBM6-carrying endoglucanases, activity was maximal on low crystallinity substrates and was stimulated by ionic strength but significant activity was also detected on microcrystalline substrates, such as Avicel and filter paper. The activity of the full length and the ΔCBM derivatives were compared to evaluate the role of the CBM in degradation of crystalline substrates.