Thermo Scientific BL21(DE3) Competent Cells are suitable for the expression of non-toxic heterologous genes. The strain contains the lambda DE3 prophage that carries the gene for T7 RNA polymerase under control of a lacUV5 promoter, allowing expression of the T7 RNA polymerase to be induced with IPTG. BL21(DE3) is an E. coli B strain and does not contain the lon protease. It is also deficient in the outer membrane protease OmpT. The lack of these two key proteases reduces degradation of heterologous proteins expressed in the cells.

• High transformation efficiency: >1x10⁷ cfu/μg pUC19 DNA
• Specifically constructed for high-level expression of recombinant proteins
• Genetic markers that minimize RNA and protein degradation
• Convenient two reactions per vial packaging
• S.O.C. Outgrowth medium included

Applications
BL21(DE3) Competent Cells are suitable for high-level T7 expression of recombinant proteins.

Genotype
F– ompT hsdS_B (r_B–, m_B–) gal dcm (DE3)

Note: Not suitable for maintenance of expression plasmids. Use DH10B or DH5α competent cells that do not carry the gene for T7 RNA polymerase for plasmid DNA propagation (Cat. Nos. EC0112, EC0113).