2014 Volume 20 Issue 2 Pages 213-218
Cellulosic biomass, such as wood waste and rice straw, remains unexploited despite the high content of cellulose. Streptomycetes are producers of industrially important antibiotics and most of the antibioticproducing strains are unable to utilize cellulose. We have, therefore, aimed to breed streptomycetes that produce antibiotics from cellulosic biomass. Two cellulolytic streptomycetes, i.e. Streptomyces thermocarboxydus C42 and Streptomyces argenteolus M178, were selected on the basis of carboxymethyl cellulose (CMC)-degrading activity from approximately 1,000 soil-isolated streptomycetes. Shotgun cloning experiments of cellulase genes from these genomic DNAs were performed in Streptomyces lividans as a host to find putative four cellulase genes, i.e. cel9AC and cel5AC from the C42 strain and cel5AM and cel12BM from the M178 strain. The transformants of S. lividans harboring the four genes subcloned in an expression plasmid showed secreted CMC-degrading cellulase (CMCase) activities, thus demonstrating successful cloning and heterologous expression of the cellulase genes from the cellulolytic streptomycetes.
