Clostridium thermocellum recombinant beta-(1,3-1,4)-glucanase LicB was expressed in Escherichia coli K-12 and purified to electrophoretic homogeneity. Specific activity of the final preparation was 12,000 U/mg. Antibodies against recombinant LicB protein reacted with a specific band of purified C. thermocellum F7 cellulosomes, suggesting localization in the extracellular multienzyme complex. This indicates that the cellulosome takes part in the hydrolysis of other polysaccharides besides cellulose.