BL21(DE3) Competent Cells
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BL21(DE3) Competent Cells
Thermo Scientific™

BL21(DE3) Competent Cells

Thermo Scientific BL21(DE3) Competent Cells are suitable for the expression of non-toxic heterologous genes. The strain contains the lambda DE3Read more
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Catalog number EC0114
Price (USD)
157.00
Each
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Price (USD)
157.00
Each
Add to cart
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 hsdSB (rB–, mB–) 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).
For Research Use Only. Not for use in diagnostic procedures.
Specifications
Product TypeCompetent Cell
EfficiencyHigh Efficiency (>1x10^7 cfu/μg pUC19 DNA)
Cell TypeChemically Competent
Cloning Methylated DNAYes
Bacterial or Yeast StrainBL21(DE3)
Blue/White ScreeningNo
Shipping ConditionDry Ice
SpeciesE. coli
PromoterLacUV5
FormatTube
Product LineThermo Scientific™
Quantity10 x 100 μL
Unit SizeEach
Contents & Storage
• 10 x BL21(DE3) Competent Cells (100 μL)
• pUC19 DNA (50 μL) (10 pg/μL)
• S.O.C. Medium (5 mL)

Store at -80°C.

Frequently asked questions (FAQs)

Can I store my competent E. coli in liquid nitrogen?

We do not recommend storing competent E. coli strains in liquid nitrogen as the extreme temperature can be harmful to the cells. Also, the plastic storage vials are not intended to withstand the extreme temperature and may crack or break.

How should I store my competent E. coli?

We recommend storing our competent E. coli strains at -80°C. Storage at warmer temperatures, even for a brief period of time, will significantly decrease transformation efficiency.

I'm getting overgrowth of colonies. Why?

Ensure that you are using the correct antibiotic at the appropriate concentration. Additionally, make sure the antibiotic is not expired. If colonies exhibit unexpected morphologies, contamination could be a factor. Check your S.O.C. medium and LB growth medium.

I'm getting no colonies at all on my plates. Can you help?

We recommend trying the following:
- Carry out the puc19 transformation control; this gives you information about the performance of the cells.
- Check plates for expiration and correct media used (LB/agar).
- Confirm that the correct antibiotic and concentration was used.

What is the storage media for the competent cells?

Preparation procedures and formulations for all of our competent cells are proprietary. All chemically competent cells are delivered in an aqueous solution that contains a mixture of salts, along with a freezing stabilizer such as glycerol or DMSO.

View all BL21(DE3) Competent Cells FAQs