BL21 (DE3)

BL21 (DE3) Chemically Competent Cells are E. coli expression hosts engineered for high-level recombinant protein production using T7 promoter–driven systems. The strain carries the DE3 lysogen, which encodes T7 RNA polymerase under the control of the lacUV5 promoter, enabling IPTG-inducible expression of T7-based constructs. Lacking lon and ompT proteases, BL21 (DE3) provides enhanced stability of expressed proteins and is ideal for expression of native or recombinant proteins, fusion constructs, and toxic gene products. Transformation efficiencies typically reach 1x107 cfu/μg pUC19 DNA under standard chemical transformation. Supplied as ready-to-use single-use aliquots for high reproducibility. Each lot is QC-tested for transformation efficiency and genotype verification.