Chemically competent cells are the most frequently used format in a wide array of applications and are transformed by heat shock—no specialized equipment required.
A complete collection of single-use and high-throughput electrocompetent and chemically competent E. coli
Choosing the ideal competent cells for your cloning applications and workflows is critical for the success of your experiment. Considerations when selecting competent cells for cloning include:
- Transformation method—chemical versus electroporation
- Downstream application—cloning unstable inserts, protein expression, library construction, or general cloning
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Benefits of buying competent cells
At Thermo Fisher Scientific, we have developed and improved proprietary methods to produce competent cells that consistently provide high transformation results. Our comprehensive range of standard and specialized strains have been engineered to help optimize your downstream experiments and streamline your cloning workflow.
The benefits of commercially manufactured cells include robust quality control to maintain high efficiency transformation, batch-to-batch consistency, and time savings. Our off-the-shelf competent cells are available in convenient formats suitable for high- and low-throughput cloning.
Competent cells by type
Choose competent cells based on transformation method.
Chemically competent cells
Electrocompetent cells
Electrocompetent cells are often preferred for library creation and low DNA input cloning applications due to very high transformation efficiencies achieved by electroporation.
Competent cells by application
Thermo Fisher Scientific offers many E. coli strains as competent cells to streamline your workflow. Determine which competent cell strain fits your needs. Tables 1, 2, and 3 provide comprehensive lists of strains suitable for various cloning applications. You can choose from several formats to serve low- or high-throughput cloning workflows.
Learn about six considerations for choosing competent cells
Download selection guide
Routine cloning and subcloning
Table 1. Strains for routine cloning and subcloning
| Application | E. coli strain | Efficiency |
|---|---|---|
| Subcloning | DH5α | >1 x 106 cfu/µg |
| Routine cloning | DH5α family* | >1 x 108 cfu/µg |
| DH10B family* | >1 x 109 cfu/µg | |
| TOP10 family* | >1 x 109 cfu/µg | |
| For fast routine cloning | Mach1 T1R* | >1 x 109 cfu/µg |
* Available in a high-throughput configuration
Specialized cloning applications
Table 2. Strains for specialty cloning applications
| Application | E. coli strain | Efficiency |
|---|---|---|
| Cloning unstable DNA | Stbl2 | > 1 x 109 cfu/µg |
| Stbl3* | > 1 x 108 cfu/µg | |
| Stbl4⚡ | > 5 x 109 cfu/µg | |
| Bacmid creation | DH10Bac | > 1 x 108 cfu/µg |
| High efficiency cloning/cDNA or genomic library construction | MegaX DH10B T1R⚡ | > 3 x 1010 cfu/µg |
| > 1 x 1010 cfu/µg | ||
| OmniMax 2 T1R | > 5 x 109 cfu/µg | |
| Stbl4⚡ | > 5 x 109 cfu/µg | |
| DH10B family⚡ | > 1 x 1010 cfu/µg | |
| Propagating unmethylated DNA | INV110 | > 1 x 106 cfu/µg |
| Cre-lox recombination | PIR1 | > 1 x 109 cfu/µg |
| PIR2 | > 1 x 108 cfu/µg | |
| Preparing single stranded DNA (ssDNA) | TOP10F´ | > 1 x 109 cfu/µg |
| TOP10F´⚡ | > 5 x 109 cfu/µg | |
| DH12S⚡ | > 1 x 1010 cfu/µg | |
| DH5αF´IQ | > 1 x 108 cfu/µg | |
| INVαF' | > 1 x 108 cfu/µg | |
| Maintaining supF-containing vectors | TOP10/P3 | > 1 x 109 cfu/µg |
| MC1061/P3 | > 1 x 108 cfu/µg | |
| Propagating Gateway vectors and plasmids with ccdB gene | ccdB Survival 2 T1R | > 1 x 109 cfu/µg |
*Available in a high-throughput configuration
⚡= Electrocompetent cells
Strains for protein expression
Table 3. Strains for protein expression
| Application | E. coli strain | Efficiency |
|---|---|---|
| High level protein expression | BL21 (DE3) | >1 x 108 cfu/µg |
| BL21 Star (DE3)* | >1 x 108 cfu/µg | |
| Toxic protein expression | BL21-AI | >1 x 108 cfu/µg |
| Improved expression regulation | BL21(DE3)pLysS | >1 x 108 cfu/µg |
| BL21(DE3)pLysE | >1 x 107 cfu/µg | |
| BL21 Star (DE3)pLysS | >1 x 108 cfu/µg |
* Available in a high-throughput configuration
Routine cloning and subcloning
Table 1. Strains for routine cloning and subcloning
| Application | E. coli strain | Efficiency |
|---|---|---|
| Subcloning | DH5α | >1 x 106 cfu/µg |
| Routine cloning | DH5α family* | >1 x 108 cfu/µg |
| DH10B family* | >1 x 109 cfu/µg | |
| TOP10 family* | >1 x 109 cfu/µg | |
| For fast routine cloning | Mach1 T1R* | >1 x 109 cfu/µg |
* Available in a high-throughput configuration
Specialized cloning applications
Table 2. Strains for specialty cloning applications
| Application | E. coli strain | Efficiency |
|---|---|---|
| Cloning unstable DNA | Stbl2 | > 1 x 109 cfu/µg |
| Stbl3* | > 1 x 108 cfu/µg | |
| Stbl4⚡ | > 5 x 109 cfu/µg | |
| Bacmid creation | DH10Bac | > 1 x 108 cfu/µg |
| High efficiency cloning/cDNA or genomic library construction | MegaX DH10B T1R⚡ | > 3 x 1010 cfu/µg |
| > 1 x 1010 cfu/µg | ||
| OmniMax 2 T1R | > 5 x 109 cfu/µg | |
| Stbl4⚡ | > 5 x 109 cfu/µg | |
| DH10B family⚡ | > 1 x 1010 cfu/µg | |
| Propagating unmethylated DNA | INV110 | > 1 x 106 cfu/µg |
| Cre-lox recombination | PIR1 | > 1 x 109 cfu/µg |
| PIR2 | > 1 x 108 cfu/µg | |
| Preparing single stranded DNA (ssDNA) | TOP10F´ | > 1 x 109 cfu/µg |
| TOP10F´⚡ | > 5 x 109 cfu/µg | |
| DH12S⚡ | > 1 x 1010 cfu/µg | |
| DH5αF´IQ | > 1 x 108 cfu/µg | |
| INVαF' | > 1 x 108 cfu/µg | |
| Maintaining supF-containing vectors | TOP10/P3 | > 1 x 109 cfu/µg |
| MC1061/P3 | > 1 x 108 cfu/µg | |
| Propagating Gateway vectors and plasmids with ccdB gene | ccdB Survival 2 T1R | > 1 x 109 cfu/µg |
*Available in a high-throughput configuration
⚡= Electrocompetent cells
Strains for protein expression
Table 3. Strains for protein expression
| Application | E. coli strain | Efficiency |
|---|---|---|
| High level protein expression | BL21 (DE3) | >1 x 108 cfu/µg |
| BL21 Star (DE3)* | >1 x 108 cfu/µg | |
| Toxic protein expression | BL21-AI | >1 x 108 cfu/µg |
| Improved expression regulation | BL21(DE3)pLysS | >1 x 108 cfu/µg |
| BL21(DE3)pLysE | >1 x 107 cfu/µg | |
| BL21 Star (DE3)pLysS | >1 x 108 cfu/µg |
* Available in a high-throughput configuration
Competent cells by format
Competent cells for cloning are offered in a variety of packaging formats to fit your needs.
One Shot format
Pre-aliquoted chemically competent cells in single-use tubes offer maximum convenience.
MultiShot FlexPlate format
Chemically competent cells for medium- to high-throughput cloning. Available in 96-tube rack, 96-well, and 96-microarray formats.
Standard format
Electro- and chemically competent cells in bulk quantities of 100 µL and higher.
These competent cells are available under license for use in your services or for use in manufacturing your products for sale. Please contact us at outlicensing@thermofisher.com.
Competent cells: Featured products
In addition to competent cells, we offer a broad suite of products for the cloning workflow.
Microbial
media
Explore types of bacterial growth media to use for cloning, plasmid DNA preparation, and protein expression.
Electroporation
cuvettes
Learn more about universal-fit electroporation cuvettes for use with competent cells.
TOPO PCR
cloning kits
Learn more about one-step PCR cloning that combines traditional restriction and ligation cloning.
Gibson Assembly
cloning kits
Gibson Assembly cloning kits provide highly efficient, seamless cloning, enabling the assembly of multiple DNA fragments of varying lengths into any vector.
Resources
Have any questions on competent cells or transformation? Click on the resources listed below to access overviews, videos, genotype guides, and educational resources.
Review rich educational content on transformation workflow, troubleshooting, strategies, and selection guides.
Stay up-to-date on industry trends in molecular cloning with on-demand webinars.
Short articles and digital handbook for cloning applications
Access white papers and technical and application notes on molecular cloning.
Watch instructional videos on troubleshooting tips, how-to videos, and explainers related to molecular cloning.
Get support for your cloning experiments
For Research Use Only. Not for use in diagnostic procedures.
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