The nucleotide sequence of the glcA gene encoding the precursor of extracellular beta-1,3-glucanase (beta Gl) A1, a polysaccharidase produced by Bacillus circulans WL-12, was determined. The putative glcA gene was 2046 bp long, encoding a polypeptide of 682 amino acids (aa). The N-terminal aa sequence of beta Gl produced in Escherichia coli harboring the glcA plasmid was identical to that of beta Gl A1 prepared from the culture fluid of B. circulans WL-12. In both proteins, cleavage of the signal sequence of pre-beta Gl occurred between Ala-38 and Ala-39 of the predicted sequences.