BL21 (DE3) Competent Cells

BL21 (DE3) Competent Cells

Chemically Competent Escherichia coli Cells optimized for Protein Expression of T7 RNA Polymerase-based systems

Product Overview:

BL21 (DE3) Competent Cells are Chemically Competent Escherichia coli Cells used for Protein Expression of T7 RNA Polymerase-based Systems. These cells are resistant to the lytic bacteriophages T1 and T5. The BL21 (DE3) strain is a derivative of E. coli B. It is deficient in both lon and ompT proteases resulting in superior isolation of intact Recombinant Proteins. The host is a lysogen of DE3 and, therefore, carries a chromosomal copy of the T7 RNA polymerase gene that is controlled by the lacUV5 promoter. The strain utilizes the T7 RNA promoter to control protein expression. IPTG is used to induce Expression of the T7 RNA Polymerase.

Genotype: F¯ ompT gal dcm lon hsdSB(rB- mB-) λ(DE3 *lacI lacUV5-T7 gene 1 ind1 sam7 nin5])

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Availability: In stock! Ready-to-ship immediately

Catalog Numbers, Sizes & Prices

Cat. No. Size Price
C0035 20 rxn 197 €


We also offer this Product with different specifications or size (Custom Solutions), in higher amounts (Bulk Inquiries) or under OEM Basis (OEM Partnerships).

Note: Prices may vary between countries, because additional cost may be applied due taxes, shipments or Custom fees.

Advantages & Features

  • High-level of Protein Expression.
  • Transformation Efficiency: ≥ 106 cfu/μg.
  • Deficient in proteases Ion and OmpT.


Genotype: F¯ ompT gal dcm lon hsdSB(rB- mB-) λ(DE3 *lacI lacUV5-T7 gene 1 ind1 sam7 nin5])


Includes for 20 rxn:

– 10 µL BL21 (DE3) Competent Cells Control Plasmid (0.1 ng/µL)
– 10 x 200μL BL21 (DE3) Competent Cells
– Dry Ice

Download documentation

Data Sheet


  • Protein Expression using the T7 Expression System.

Quality Control

  • BL21(DE3) Competent Cells consistently yield > 1.0 × 106 colony-forming units/µg competent cells control plasmid when transformed with non-saturating amounts of DNA (0.2ng/100 µL cells).

Storage, Shipping & Guarantee​

  • Shipment with Dry Ice.
  • Storage: Upon receipt of the kit, immediately store the components at -80 °C. Storage at -20 °C will result in a significant decrease in transformation efficiency. Please note that Competent Cells are very sensitive to cycles of freezing and thawing and should not be exposed to temperature variations.
  • Shelf Life: 6 months from the date of purchase, if it is properly stored.

Safety Statements

This product is developed, designed and sold exclusively for Research purposes and in vitro use only (RUO). The product was not tested for use in diagnostics or for drug development, nor is it suitable for administration to humans or animals. For more info, please check its Material Safety Data Sheet available in this website.

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