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Home >  Technical Reference > Competent Cells
An Introduction to Competent E. coli
 
NEB's growing line of competent cells include several popular cloning and protein expression strains, in addition to strains with unique properties. The following selection charts highlight the characteristics of these strains to help you select the best strain for your particular experiment

Advantages of NEB Competent Cells

  • No animal products used
  • T1 phage resistance (fhuA2)
  • Media and control plasmid included
  • A variety of convenient formats, including single use transformation tubes and, on request, 96 well plates
  • Bulk sales capabilities with custom packaging.
Request your copy or
Download pdf Competent Cell Brochure

Strain Selection Chart

Characteristics Strain
Fastest Growth – Colonies Visible After 6.5 Hours NEB Turbo High Efficiency
NEB Turbo Electrocompetent
Versatile Cloning NEB 5-alpha High Efficiency
NEB 5-alpha Subcloning Efficiency
NEB 5-alpha Eletrocompetent
Cloning of Toxic Gene NEB 5-alpha F'Iq High Efficiency
Cloning of Large Plasmids and BACs NEB 10-beta High Efficiency
NEB 10-beta Electrocompetent
Growth of Unmethylated Plasmids   dam–/dcm–
Most Popular non-T7 Protein Expression Strain NEB Express High Efficiency
Control of IPTG Induced Protein Expression NEB Express Iq High Efficiency
Most Popular T7 Protein Expression Strain T7 Express High Efficiency
Reduced Basal Expression T7 Express Iq High Efficiency
Tight Control of Protein Expressionby Inhibition
  of T7 RNA Polymerase  		 T7 Express lysY High Efficiency
Highest Level of Protein Expression Control T7 Express lysY/Iq High Efficiency
For Crystallography Experiments/SeMet Labeling T7 Express Crystal High Efficiency

Strain Property Chart

  Transform
Efficiency
(cfu/µg)		 Strain T1
Phage
Resistant		 Blue/
White
Screening		 laclq lysY Colonies
Visible
after 6.5h		 Endo-
nucleaseI
Deficient		 Protease
Deficient		 Eukaryotic
DNA
Cloning		 M13
Phage
Capable
(F+)		 RecA
Deficient
NEB Turbo 1-3x109 K12 √ √ √ - √ √ - - √ -
NEB 5-alpha 1-3x109 K12 √ √ - - - √ - - - √
NEB 5-alpha Subcloning 1x106 K12 √ √ - - - √ - - - √
NEB 5-alpha
  Electrocompetent		 2-4x1010 K12 √ √ - - - √ - - - √
NEB 5-alpha F'Iq 1-3x109 K12 √ √ √ - - √ - - √ √
NEB 10-beta 1-3x109 K12 √ √ - - - √ - √ - √
NEB 10-beta
  Electrocompetent		 2-4x1010 K12 √ √ - - - √ - √ - √
NEB Turbo
  Electrocompetent		 2-4x1010 K12 √ √ √ - √ √ - - √ √
dam–/dcm– 1-3x106 K12 √ - - - - √ - - - -
NEB Express 0.6-1x108 B √ - - - - √ √ √ - -
NEB Express Iq 0.6-1x108 B √ - √ - - √ √ √ - -
T7 Express 0.6-1x108 B √ - - - - √ √ √ - -
T7 Express Iq 0.6-1x108 B √ - √ - - √ √ √ - -
T7 Express lysY 0.6-1x108 B √ - - √ - √ √ √ - -
T7 Express lysY/Iq 0.6-1x108 B √ - √ √ - √ √ √ - -
T7 Express Crystal 0.6-1x108 B √ - - - - √ √ √ - -

(From NEB Expressions 2007, vol. 1.4. updated on 9/25/2007)