The actinomycete Streptomyces sp. QM-B814 is able to use polymeric glucans as sole carbon source by the induction of specific extracellular enzymatic systems. Carboxymethylcellulose and barley β-glucan were the most effective inducers of endoglucanase activities towards β-(1,4) and mixed β-(1,3)-(1,4) linkages. Avicelase activity was induced by Avicel and carboxymethylcellulose. The higher activity towards filter paper (cellulase) was measured in cultures growing in Avicel, carboxymethylcellulose, and barley β-glucan. Laminarinase activity was induced only by laminarin and lichenan failed to induce significant activity levels against any of the substrates tested. © 1994 Science and Technology Letters.