Cloning of ten distinct DNA fragments of<i>Clostridium thermocellum</i>coding for cellulases

Abstract

Ten distinct Eco RI fragments of Clostridum thermocellum DNA have been cloned in Escherichia coli and shown to express enzymatic activities related to cellulose degradation. Two of the cloned fragments appeared to carry the previously characterized celA and celB genes, which code for the endoglucanases (EG) A and B. Five other cloned fragments code for hitherto unidentified EGs, which can be detected by the Congo red test for hydrolysis of carboxymethylcellulose (CMC). In addition, three separate clones hydrolyzed methylumbelliferyl-β-cellobioside (MUC) but not CMC, hinting that they may express three different cellobiohydrolase genes.