Streptomyces matensis DIC-108 secretes a laminaripentaose-producing beta-1,3-glucanase (LPHase) into the culture medium. LPHase was partially purified and its N-terminal amino acid sequence was determined. The gene (Iph) for LPHase was cloned using a colony hybridization technique and a synthetic oligonucleotide probe designed from the N-terminal amino acid sequence, and the nucleotide sequence of Eph was determined. Iph has an open reading frame of 1203 bp that encode a polypeptide of 401 amino acids including a putative 35-amino acid signal sequence. The mature portion of the polypeptide showed significant sequence similarity with the catalytic domains of beta-1,3-glucanases of Oerskovia xanthineolytica and Arthrobacter sp. strain YCWD3. Since Iph was not expressed in Escherichia coli, the coding region of Iph was amplified by PCR and ligated into the expression vector pKK233-2. E. coil JM109 cells carrying the resultant plasmid pKK-lph produced beta-1,3-glucanase of a size identical to that of LPHase produced by S. matensis DIC-108, and the enzyme exclusively liberated laminaripentaose from insoluble beta-l,3-glucan.