A carboxymethyl cellulase gene, cel5B, was cloned, sequenced, and expressed in Escherichia coli. pRCS20 in E. coli was identified from metagenomic cosmid library of cow rumen for cellulase activity on a carboxymethyl cellulose agar plates. Cosmid clone (RCS20) was partially digested with Sau3AI, ligated into BamHI site of pBluescript II SK+ vector, and transformed into E. coli DH5α. The insert ...