Cloning of $\beta$-glucosidase gene from Cellulomonas sp. into E.coli

To clone ${\beta}$-glucosidase gene from Cellulomonas sp. a gene library was constructed using E. coli JM83 pUC9. Among 2,500 pseudotransformants obtained, 20 clones developed yellow color on the p-nitrophenyl- -D-glucopyranoside filter paper These 20 clones were classified into three groups based on the results of activity staining using nondenaturating polyacrylamide gel electrophoresis and restriction enzyme digestions. Among the three groups, only one group containing pCEl plasmid has specificity for cellobiose.