A gene library of Cellulomonas pachnodae was constructed in Escherichia coli and was screened for endoglucanase activity. Five endoglucanase-positive clones were isolated that carried identical DNA fragments. The gene, designated ce16A, encoding an endoglucanase enzyme, belongs to the glycosyl hydrolase family 6 (cellulase family B). The recombinant Ce16A had a molecular mass of 53 kDa, a pH optimum of 5.5, and a temperature optimum of 50-55 degrees C. The recombinant endoglucanase Ce16A bound to crystalline cellulose and beech litter. Based on amino acid sequence similarity, a clear cellulose-binding domain was not distinguished. However, the regions in the Ce16A amino acid sequence at the positions 262-319 and 448-473, which did not show similarity to any of the known family-6 glycosyl hydrolases, may be involved in substrate binding.