Krill are filter feeders that consume algae, plankton and detritus, indicating that krill possess an adequate cellulose
digesting system. However, less is known about the enzymatic properties of crustacean cellulases compared to
termite cellulases. In the present study, 48 kDa-cellulase was highly purified from krill (Euphausia pacifica) in an
effort to determine the cleavage specificity of the enzyme. The most notable characteristic of the enzyme was its
high activity against both lichenan and carboxymethyl cellulose. The enzyme hydrolyzed internal β-1,4 glycosidic
bonds within lichenan as well as carboxymethyl cellulose to release oligosaccharides and glucose. The effects
of pH and temperature on the activity and stability of both enzyme activities were almost identical. Cellooligosaccharides
with a degree of polymerization of 4–6 were hydrolyzed by the enzyme, and the same
endo-products, cellotriose, cellobiose and glucose, were produced from these oligosaccharides. Neither cellotriose
nor cellobiose was hydrolyzed by the enzyme. The enzyme digested filter paper and sea lettuce to produce cellobiose,
cellotriose and glucose as major products. Although amino acid sequence homology of the enzyme with termite
cellulases and the presence of oligosaccharides in the enzyme suggested that the enzyme is produced by krill itself,
further analysis is necessary.