Molecular Characterization of Four Strains of the Cellulolytic ThermophileClostridium Stercorarium

Abstract

Four strains of Clostridium stercorarium, including three isolates with increased capacity to hydrolyze crystalline cellulose and assigned to the species, were characterized using recombinant DNA techniques, and compared to C. thermocellum. Their genomic DNA contained 3.0 megabases with 43% G+C. The genomic DNA fragment pattern was identified for the restriction endonucleases NotI and SfiI. Key enzymes of cellulolysis and hemicellulolysis were shown to be present in the genomic DNA of the new strains. A partial physical genomic map containing 6 genes involved in polysaccharide degradation for the type strain and 4 genes for the new isolates is presented. Strains of the species characteristically produced two extracellular cellulose binding proteins representing Avicelase I and II. The methods described allow us to ascribe the newly isolated thermophilic cellulolytic bacteria to the species C. stercorarium and are a basis for molecular biological work on that organism.